twander(1)twander(1)NAMEtwander - File Browser
OVERVIEW
Wander around a filesystem executing commands of your choice on
selected files and directories. The general idea here is that twander
provides GUI facilities for navigating around your filesystem, but you
define the commands you want available via "Command Definitions" (in
the Configuration File). In other words, twander can't do anything
useful until you've defined some commands. This document describes
how to install and start twander as well as it's various startup
options.
This document also describes the format and content of a twander Con‐
figuration File. You will find an example Configuration File called
.twander in the distribution tarball. All the entries in that file are
commented out, so you'll need to uncomment and edit the ones you want
to work with.
If you're new to twander and want to know why this program is better
and different than whatever you're using at the moment, take a moment
to read the section called DESIGN PHILOSOPHY toward the end of this
document first.
Similarly, if this is the first time you've worked with twander, there
is a section near the end of this document entitled INSTALLING twander
which describes how the program should be installed.
You can get the latest version of the program and documentation from
the twander homepage:
http://www.tundraware.com/Software/twander/
You should check this site periodically for program updates, bug fixes,
and enhancements.
Also, you are strongly encouraged to join the twander mailing list
where you'll find help and answers to questions you have about this
program. Details of how to do this can be found toward the end of this
document in the section entitled, GETTING HELP: THE twander MAILING
LIST.
SYNOPSIStwander [-cdhqrtv] [startdir]
OPTIONS
startdir
Directory in which to begin. (default: directory in which pro‐
gram was started)
If this directory does not exist or cannot be opened, twander
will display an error message and abort.
-c path/name of Configuration File
Specify the location and name of the configuration file.
(default is ~/.twander)
If this file does not exist or cannot be opened, twander will
display a warning to that effect but continue to run. This is
reasonable behavior because twander provides a command to reload
the Configuration File without exiting the program (which you
would presumably do after fixing the Configuration File prob‐
lem).
-d debuglevel
Start in debug mode dumping the items specified in the debu‐
glevel. (default: debuglevel=0/debug off)
twander is able to selectively dump debugging information to
stdout. ´debuglevel´ is understood to be a bitfield in which
each bit specifies some kind of debugging information or behav‐
ior. ´debuglevel´ can be specified in either decimal or hex
(using the form 0x#) formats. The bits in the bitfield are
defined as follows:
Bit Hex Value Meaning
-------------------
0 0x001 Dump Internal Options & User-Settable Options
1 0x002 Dump User-Defined Variables
2 0x004 Dump Command Definitions
3 0x008 Dump Key Bindings
4 0x010 Display, Do Not Execute, Commands When Invoked
5 0x020 Dump Directory Stack As It Changes
6 0x040 Dump Command History Stack After Command Executes
7 0x080 Dump Contents Of Program Memories As They Change
8 0x100 Dump Contents Of Filter/Selection Wildcard Lists As They Change (0x100)
9 0x200 Dump Associations Table
10 0x400 Reserved/Unused
11 0x800 Dump Requested Debug Information And Exit Immediately
These bits can be combined to provided very specific debugging
information. For example, ´-d 0x80f´ will dump (to stdout) all
the Internal Options, User-Settable Options, User-Defined
Options, Command Definitions, and Key Bindings and then termi‐
nate the program.
-h Print help information on stdout.
-q Quiet mode - suppresses warnings. (default: warnings on)
-r Turn off automatic refreshing of directory display. (default:
refresh on)
Normally twander re-reads and displays the current directory
every few seconds to reflect any changes that might have
occurred to that directory's contents. This option is useful on
slow machines (or slow X connections) and/or when working with
very large directories. In this situation, the frequent updat‐
ing of the twander display can make the program unacceptably
slow and unresponsive. In this case you can still force an
update manually with the REFRESH function (default assignment is
to the Control-l key).
-t Turn off quoting when substituting built-in variables. (default:
quoting on)
Anytime twander encounters a reference to one of the built-in
variables which do string replacement (DIR, DSELECTION, DSELEC‐
TIONS, MEM1-12, PROMPT:, SELECTION, SELECTIONS) in a command, it
will replace them with double quoted strings. This is necessary
because any of these can return values which have embedded spa‐
ces in them. By quoting them, they can be passed to a command
or script as a single item. The -t option disables this behav‐
ior and replaces the built-in variable with unquoted literals.
-v Print detailed version information.
OTHER WAYS TO SET twander OPTIONS
In addition to these command line options, there are two other ways you
can set twander program features. If you prefer, you can set the com‐
mand line options via the environment variable, TWANDER. That way you
don't have to type them in each time you start the program. Say you
set the environment variable this way on Unix:
export TWANDER=-qt
From then on, every time you run the program, the -q and -t options
would be invoked (No Quoting, No Warnings) just as if you had typed
them in on the command line.
The second way to set these (and MANY more) Program Options is by set‐
ting the appropriate entries in the Configuration File. This is cov‐
ered later in this document.
twander evaluates options in the following order (from first to last):
· Internally set default value of options
· Options set in the Configuration File
· Options set in the TWANDER environment variable
· Options set on the command line
This means, for example, that the environment variable overrides a cor‐
responding setting in the Configuration File, but the command line
overrides the environment variable. Furthermore, there are many Pro‐
gram Options which can only be set/changed the Configuration File and
are not available in either the environment variable or on the command
line.
This also means that options set on the command line are not read until
after the Configuration File has been processed. So, the -q argument
on the command line will not inhibit warnings generated during the
reading of the Configuration File. This is best done by adding the
statement, WARN=False, at the top of the Configuration File.
If the Configuration File is reloaded while the program is running (see
the READCONF key below), any options set in the file will have the last
word. This allows you to edit the Configuration File and have your
changes reflected in a running instance of twander, but it also means
that the environment variable/command line arguments are ignored after
initial program startup.
THE TITLE BARtwander displays a lot of information about the state of the running
program in the main window title bar. From left to right you will see:
· Program name and version number.
· Login name and machine/domain of current user.
· The path of the directory you are currently viewing. If this path
length is greater than 60 characters, twander will show the last 60
characters of the path length, prepended with "..." to show that it
is truncated.
Directories relative to your home directory will have the home
directory string replaced with "~" (a common Unix shorthand for
"home directory" in order to save title bar space.
·
The status of various symbolic link processing options. See the
program options, SYMDIR, SYMEXPAND, and SYMRESOLV for a more com‐
plete explanation.
·
Any "filter" that is limiting which files you see. If you've tog‐
gled the filter, you will see the word "NOT" before the filter
string.
· An indication of whether or not "dotfiles" are currently hidden.
· The total number of files in this directory. The ".." entry is not
included in this count.
· The total size of all the files in this directory. The size of the
".." directory is not included in this total.
· They key used to sort the display. If a reverse sort is selected,
you will see "-" appended to the end of the key to indicated this.
"Sort By: NAME-" means you are doing a reverse sort by name.
· An indication of whether or not directories and ordinary files are
being separated in the display.
· An indication of whether or not automatic refreshing is enabled.
Anytime refreshing is actually underway, whether automatic, manual,
because you are executing a command that forces a refresh, or just
because you changed directories, you will see the '*' character
appended to this field. Ordinarily, this happens so quickly you
will not see it. However, on really large directories and/or very
slow disks like CDROMs, you'll see the asterisk stay on for some
time. During refresh, the program is locked from user input. On
very long refreshes, it can appear to be "hung". This indicator is
there just to let you know the program is busy refreshing and all
is well.
KEYBOARD USE
By design, twander allows you to do almost everything of interest using
only the keyboard. Various twander features are thus associated with
particular keystrokes which are described below. It is also very sim‐
ple to change the default key assignments with entries in the Configu‐
ration File, also described below.
NOTES ON KEYBOARD ARROW/KEYPAD BEHAVIOR AND TEXT DIALOG EDITS
Generally, the arrow and keypad keys should do what you would expect on
the system in question. On Windows systems, particularly, there ought
to be no odd arrow/keypad behavior.
X-Windows is somewhat more problematic in this area. Just what an
arrow key is "supposed" to do depends on how it's been mapped in your X
server software. Testing twander on various X servers showed quite a
bit of variability in how they handled the arrows and keypad. So ...
if you're running in an X Windows universe and arrows or keypad do
nothing, or do strange things, look into your key maps, don't blame
twander.
There are several features of twander that will present the user a text
entry dialog. These include the CHANGEDIR and RUNCMD features as well
as the {PROMPT:...} Built-In Variable (all described below).
Any time you are entering text in such a dialog, be aware that the text
can be edited several ways - You can edit it using the arrow/keypad
editing assignments which are enabled/normal for your operating system,
OR you can use emacs-style commands to edit the text. For instance,
Control-a, Control-k will erase the text currently entered in the dia‐
log.
DEFAULT KEYBOARD AND MOUSE BINDINGS
Here, ordered by category, are the default keyboard and mouse bindings
for twander. The general format is:
Description (Program Function Name)
Default Key Assignment
Default Mouse Assignment (if any)
The "Program Function Name" is the internal variable twander uses to
associate a particular feature with a particular keystroke or mouse
action. You can ignore it unless you intend to override the default
key assignments. This use is described below in the section entitled,
Key Binding Statements.
It is important to realize that twander key-bindings are case-sensi‐
tive. This means that ´Control-b´ and ´Control-B´ are different. This
was a conscious design decision because it effectively doubles the num‐
ber of Control/Alt key combinations available for the addition of
future features.
The default bindings chosen for twander features are all currently
lower-case. If your program suddenly stops responding to keyboard com‐
mands, check to make sure you don't have CapsLock turned on.
NOTE: Some twander features are doubled on the mouse. These mouse but‐
ton assignments are documented below for the sake of completeness.
However, mouse button assignments cannot be changed by the user, even
in the Configuration File.
General Program Commands
This family of commands controls the operation of twander itself.
Clear History (CLRHIST)
Control-y
Clears out various program histories including the All Visited
Directories list, the Directory Stack, the Command History, and
the last manually-entered values for CHANGEDIR and RUNCMD. The
12 Program Memories are not cleared - they have specially dedi‐
cated key bindings for this purpose.
Decrement Font Size (FONTDECR)
Control-[
Decrease font size.
Increment Font Size (FONTINCR)
Control-]
Increase font size.
These two features allow you to change the display font sizes
while twander is running. But, you may not immediately get the
results you expect. twander internally keeps track of separate
font sizes for the main display, the main menu text, and the
help menu text. When you use the two font sizing commands
above, twander subtracts or adds 1 to each of these three values
respectively. On systems like Windows using TrueType fonts,
this works as you would expect, because every font is effec‐
tively available in every size. However, in systems like X-Win‐
dows or Windows using fixed-size fonts, you may have to press
these keys repeatedly until twander finds a font matching the
requested size.
This can also cause some parts of the display to change but not
others. Suppose you are running on X-Windows and have specified
that the main display is to use a 12 point font, and that menus
and help should use 10 point font. Let's also suppose that the
next font available larger than 12 point is 16 point. If you
press FONTINCR twice, both the menu text and help text will jump
to 12 point, but the main display text will remain unchanged.
Why? Because pressing FONTINCR twice tells twander to set the
main display to 14 point (12+1+1) which does not exist, and the
menu and help text to 12 point (10+1+1) which does exist, so
that change is visible.
The "User-Settable Options" Help Menu displays the font metrics
(name, size, weight) you've currently specified. Pressing FONT‐
DECR/FONTINCR changes the size specification and this will be
reflected in that menu. However, most systems do some form of
"best match" font substitution - if you ask for a font that does
not exist, the system will use the "closest matching" font as a
substitute. This means the font you see specified in the Help
Menu is not necessarily the font you're actually using. You're
more likely to run into this when running on a Unix/X-Windows
system (where not all the fonts are available in all
sizes/weights like they are on Windows TrueType) as you change
the font size with FONTDECR/FONTINCR.
Reloading the Configuration File (READCONF) will reset the fonts
to either their default values or any font sizes specified in
the Configuration File.
Display Command Menu (MOUSECTX)
Right-Mouse-Button
Displays a list of all available commands in a pop-up menu near
the mouse pointer. If no commands are defined, this feature
does nothing at all. This means commands can be invoked one of
three ways: Directly via the Command Key defined in the Configu‐
ration File, via selection in the Command Menu at the top of the
GUI, or via selection from the Command Menu.
Windows users should note that, unlike Windows Explorer, the
twander Command Menu does not change the set of currently
selected items. It merely provides a list of available com‐
mands. This allows the command chosen via the Command Menu to
operate on a previously selected set of items.
Display Directory Menu (MOUSEDIR)
Shift-Right-Mouse-Button
Displays a list of all the directories visited so far in a pop-
up menu near the mouse. This means that you can navigate to a
previously visited directory in one of two ways: Via a selection
in the Directory Menu at the top of the GUI or via a selection
from this pop-up menu.
Display History Menu (MOUSEHIST)
Control-Shift-Right-Mouse-Button
Displays a list of all commands executed so far (including those
entered manually) in a pop-up menu near the mouse pointer. If
the Command History is empty, this command does nothing. This
means you can repeat a previously entered command via the His‐
tory Menu or this mouse command. (You can also repeat the last
manually entered command by pressing RUNCMD - it will preload
its text entry area with the last command you entered by hand.)
Display Shortcut Menu (MOUSESC)
Alt-Control-Left-Mouse-Button
Displays a list of all user-defined directory shortcuts in a
pop-up menu near the mouse. The menu also has "canned" naviga‐
tion shortcuts to go up a directory, back a directory, to the
home directory, to the starting directory, and to the root
directory. On Windows systems with the Win32All extensions,
there is also a shortcut to the Drive List View.
Display Sorting Menu (MOUSESORT)
Alt-Shift-Right-Mouse-Button
(Note that on Windows you must press Alt then Shift then the
Right-Mouse-Button for this to work. Windows appears to care
deeply about keystroke order.)
Displays a list of all the sorting options in a pop-up menu near
the mouse.
Quit Program (QUITPROG)
Control-q
Exit the program.
Re-Read Configuration File (READCONF)
Control-r
Re-read the Configuration File. This allows you to edit the
Configuration File while twander is running and then read your
changes in without having to exit the program. This is handy
when editing or changing Command Definitions.
Program Options are set back to their default each time a Con‐
figuration File is about to be read (initially or on reload)
just before the Configuration File is parsed. This means com‐
menting out or removing a Program Option Statement (see relevant
section below) in the Configuration File and then pressing READ‐
CONF causes that option to be reset to its default value.
STARTDIR defaults to either its internal default ($HOME or ./)
or to the value given in the Environment Variable/Command line.
Refresh Display (REFRESH)
Control-l
Re-read the current directory's contents and display it. This
is most useful if you have turned off automatic directory
refreshing with either the -r command line flag or setting the
AUTOREFRESH Program Option to False.
Toggle Autorefreshing (TOGAUTO)
Control-o
Toggle Autorefreshing on- and off. This is handy if you are
about to enter a very large directory and/or a very slow disk
(like a CDROM). With very large or slow directory reads, twan‐
der can end up spending all its time doing re-reads of the
directory and never give you time to do anything there. If you
find this is consistently the case, then you need to increase
REFRESHINT. But for the occasional adventure into very
large/slow directories, just toggling Autorefresh off is more
convenient.
The state of the Autorefresh feature is displayed on the main
window title bar.
Toggle Details (TOGDETAIL)
Control-t
Toggle between detailed and filename-only views of the direc‐
tory.
Toggle Between Normalized And Actual File Length Display (TOGLENGTH)
Control-0
By default, the program "normalizes" file sizes and expresses
them in bytes, Kilobytes, Megabytes, or Gigabytes rather than
showing their actual size. This is done everywhere a file size
is displayed: on individual files, the total files size dis‐
played on the title bar, and the drive sizes in Win32 Drive List
View. This key binding invokes a feature that toggles these
size displays between normalized and actual. See the ACTUAL‐
LENGTH configuration option below to set the default as you pre‐
fer it.
Toggle Sorting Of Symbolic Link Directories (TOGSYMDIR)
Control-~
Toggles whether symbolic links pointing to directories should be
sorted as directories or as files. This changes the state of
the SYMDIR program option (default: True) and updates the title
bar "Symlinks:" status field. This is only meaningful if you've
selected "separated" sorting (SORTSEP) to cluster directories
and then files together in the display.
Toggle The Display Of Symbolic Link Targets (TOGSYMEXPAND)
Control-!
Toggles whether or not to display the targets of symbolic links
or to just display the link name by itself. This changes the
state of the SYMEXPAND program option (default: True) and
updates the title bar "Symlinks:" status field.
Toggle The Display Of Absolute Symbolic Link Targets(TOGSYMRESOLV)
Control-@
Toggles whether the targets of symbolic links should be dis‐
played as defined or in absolute path format. This changes the
state of the SYMRESOLV program option (default: False) and
updates the title bar "Symlinks:" status field. Pressing this
key implies you want to see symbolic link targets (either as
defined or as "resolved" absolute paths) so this keypress also
forces SYMEXPAND to True.
Toggle ´win32all´ Features (TOGWIN32ALL)
Control-w
As described later in this document, twander provides enhanced
features for Windows users who also install Mark Hammond's
´win32all´ extensions for Python on Windows. This key binding
will toggle those advanced features on- and off. This is useful
if you happen to be examining a very large directory. The
´win32all´ features, while handy, can be computationally expen‐
sive and make updates of a directory with many entries somewhat
slow. This toggle is provided as a means to temporarily disable
the advanced features when viewing such a directory.
Directory Navigation
This family of commands controls movement between directories. If you
attempt to navigate into a directory that does not exist or which does
not have appropriate permissions, twander will display a warning mes‐
sage and remain in the current directory. This is unlike the case of a
non-existent or unreadable directory specified when the program is
first started. In that case, twander reports the error and aborts.
Change Directory (CHANGEDIR)
Control-x
This is a shortcut that allows you to directly move to a new
directory/path - i.e., Without having to navigate to it.
Unless you have set the MAXMENU option to 0, CHANGEDIR keeps
track of your last manually entered directory and presents it as
a default when you press CHANGEDIR again. You can then move to
that directory, edit the string to specify another directory, or
delete it and enter an entirely new directory. Directories can
be edited with either the arrow and keypad keys defined on your
system or by emacs editing commands like Control-a, Control-k,
Control-e, and so forth.
Go To Home Directory (DIRHOME)
Control-h
If the "HOME" environment variable is defined on your system,
this will move you to that directory. If the "HOME" environment
variable is not defined, this command will move to the original
starting directory.
Go Back One Directory (DIRBACK and MOUSEBACK)
Control-b
Control-DoubleClick-Left-Mouse-Button
twander keeps track of every directory visited and the order in
which they are visited. This command allows you to move back
successively until you get to the directory in which you
started. This feature is implemented as a stack - each "backing
up" removes the directory name from the visited list. The
"Directory" menu (see MENU OPTIONS below) implements a similar
feature in a different way and keeps track of all directories
visited regardless of order.
Go To Root Directory (DIRROOT)
Control-j
Go to the root directory.
Go To Starting Directory (DIRSTART)
Control-s
Go back to the original directory in which twander was started.
Go Up To Parent Directory (DIRUP and MOUSEUP)
Control-u
Control-DoubleClick-Right-Mouse-Button
Move to the parent of the current directory ("..").
Display Drive List View (DRIVELIST)
Control-k
This is a Windows-only feature which displays a list of all
available disk drives. Details about each drive are also dis‐
played if you have details enabled. In order for this feature
to work, you must be running on Windows AND have the ´win32all´
package installed, AND the USEWIN32ALL Program Option must be
True (default condition,) AND you must not have toggled these
features off with the TOGWIN32ALL key described above. For more
details about Drive List View, see the section below entitled,
ADVANCED WINDOWS FEATURES.
Selection Keys
This family of commands controls the selection of one or more (or no)
items in the current directory.
Select All Items (SELALL)
Control-Comma
Select every item in the current directory. The ".." entry at
the top of the directory listing is not included. (We almost
never want to include the parent directory when issuing a com‐
mand on "everything in this directory". If you do wish to
include the "..", do the SELALL command first, then click on
".." while holding down the Control key.)
Invert Current Selection (SELINV)
Control-i
Unselects everything which was selected and selects everything
which was not. As with SELALL, and for the same reason, the
".." entry is never selected on an inversion.
Unselect All Items (SELNONE)
Control-Period
Unselect everything in the current directory.
Select Next Item (SELNEXT)
Control-n
Select next item down in the directory.
Select Previous Item (SELPREV)
Control-p
Select previous item up in the directory.
Select Last Item (SELEND)
Control-e
Select last item in the directory.
Select First Item (SELTOP)
Control-a
Select first item in the directory. This will always be the
".." entry, but it is a quick way to get to the first part of a
very long directory listing which does not all fit on-screen.
Mouse-Based Selections
The mouse can also be used to select one or more items. A sin‐
gle-click of the left mouse button selects a particular item.
Clicking and dragging selects an adjacent group of items.
Clicking an item and then clicking a second item while holding
down the "Shift" key also selects an adjacent group of items.
Finally, a group of non-adjacent items can also be selected.
The first item is selected with a single left mouse button click
as usual. Each subsequent (non-adjacent) item is then selected
by holding down the "Control" key when clicking on the item.
Scrolling Commands
If a given directory's contents cannot be displayed on a single screen,
twander supports both vertical and horizontal scrolling via scrollbars.
This capability is doubled on the keyboard with:
Scroll Page Down (PGDN)
Control-v
Scroll down one page in the directory listing.
Scroll Page Up (PGUP)
Control-c
Scroll up one page in the directory listing.
Scroll Page Right (PGRT)
Control-g
Scroll to the right one page width.
Scroll Page Left (PGLFT)
Control-f
Scroll to the left one page width.
Command Execution Options
This family of commands causes twander to actually attempt to execute
some command you've chosen:
Run Arbitrary Command (RUNCMD)
Control-z
This is a shortcut that allows you to run any command you'd like
without having to define it ahead of time in the Configuration
File. It is more-or-less like having a miniature command line
environment at your disposal.
You may enter a number of different things in the RUNCMD dialog.
You may type literal text or refer to any of the variable types
(User-Defined, Environment, or Built-In) supported by twander
just as you do in writing Command Definitions (see below). This
makes it easy to enter complex commands without having to type
everything literally. For example, if you would like to copy
all the currently selected files to a new directory, press
RUNCMD and enter (on Unix):
cp [SELECTIONS] newdir
twander understands the variable reference syntax here just as
it does in a Command Definition. This also gives you a single
way of referring to environment variables, regardless of OS
platform. Recall that in Unix-like shells, an environment vari‐
able is in the form "$NAME", but on Windows it is in the form
"%NAME%". Instead if having to keep track of this difference,
you can just use a twander Environment Variable reference. For
instance, assuming the EDITOR environment variable is set, this
command works the same on both systems:
[$EDITOR] [SELECTIONS]
Built-in variables are most often used when manually entering
commands So, RUNCMD also understands some "shortcut" references
to many of the built-ins. You may use:
[D] for [DIR]
[DN] for [DSELECTION]
[DS] for [DSELECTIONS]
[SN] for [SELECTION]
[SS] for [SELECTIONS]
[1] for [MEM1]
[2] for [MEM2]
[3] for [MEM3]
[4] for [MEM4]
[5] for [MEM5]
[6] for [MEM6]
[7] for [MEM7]
[8] for [MEM8]
[9] for [MEM9]
[10] for [MEM10]
[11] for [MEM11]
[12] for [MEM12]
Of course, the full form is also fine as well.
This shortcut feature is only supported in RUNCMD!!! Configura‐
tion File entries must use the full form of all built-in vari‐
ables. This is a conscious design decision to help enforce some
consistency and clarity in the Configuration Files.
Unless you have set the MAXMENU option to 0, RUNCMD keeps track
of your last manually entered command and presents it as a
default when you press RUNCMD again. You can then run the com‐
mand again exactly as you last entered it, you can modify it
before running the command again, or you can delete it and enter
an entirely new command. Commands can be edited with either the
arrow and keypad keys defined on your system or by emacs editing
commands like Control-a, Control-k, Control-e, and so forth.
Also see the section below entitled, Program Option Statements,
to understand the CMDSHELL option. This option greatly simpli‐
fies running command-line programs from RUNCMD so their output
can been seen in a GUI window. This is particularly handy on
Unix.
As with command definitions in a Configuration File, you can
tell twander to force a display refresh after the command has
been initiated. You do this by beginning the command with the
´+´ symbol. So, for example, if you enter,
+mycommand
twander will initiate the command, wait AFTERWAIT seconds
(default: 1), and then update the display. See the discussion
below entitled, Forcing Display Updates In Command Definitions
for a more complete explanation.
This feature may be used in combination with CMDSHELL escaping
(also described in the Program Option Statements section below)
and the two characters may appear in any order at the beginning
of the command line you enter.
Run Selected File / Move To Selected Directory (SELKEY and MOUSESEL)
Return (Enter Key)
DoubleClick-Left-Mouse-Button
If the selected item is a Directory, twander will move into that
directory when this command is issued. If the selected item is
a file, twander will attempt to execute it. Whether or not the
file is actually executed depends on how the underlying operat‐
ing system views that file.
In the case of Unix-like operating systems, the execute permis‐
sion must be set for the user running twander (or their group)
for the file to be executed.
On Windows, the file will be executed if the user has permission
to do so and that file is either executable or there is a Win‐
dows association defined for that file type. For example, dou‐
ble-clicking on a file ending with ".txt" will cause the file to
be opened with the ´notepad´ program (unless the association for
".txt" has been changed).
If twander determines that it is running on neither a Unix-like
or Windows system, double-clicking on a file does nothing.
Run User-Defined Command
User-Defined (Single Letter) Key
Each command defined in the Configuration File has a Command Key
associated with it. Pressing that key will cause the associated
command to be run. If no command is associated with a given
keystroke, nothing will happen when it is pressed.
Directory Shortcuts
twander provides a way to directly navigate into a frequently-used
directory using a single keystroke. You can define up to 12 such
"Directory Shortcuts" in the Configuration File. Each of the defini‐
tions is associated with one of the following 12 keys:
Navigate Directly To A Directory (KDIRSC1 ... KDIRSC12)
F1 ... F12
Pressing one of these keys changes to the directory associated
with it in the Configuration File. For more information on this
topic, see the discussion of the Configuration File below enti‐
tled, Directory Shortcut Statements
Assign Current Directory To One Of The Shortcut Keys (KDIRSCSET)
Control-8
As discussed in Directory Shortcut Statements , the directory
shortcut keys are associated with particular directories in the
twander Configuration File. However, it is possible to tempo‐
rarily assign them to something else while the program is run‐
ning. This is handy if you need to temporarily "remember" one
or more directories so you can jump back to them with a single
keystroke. Think of it as a way to "override" the directory
shortcut assignments defined in the Configuration File.
To do this, press the KDIRSCSET key (Default: Control-8). You
will be presented with a dialog that asks you to specify which
Directory Shortcut you want overwritten with the current direc‐
tory. You may only enter a number from 1 to 12. You will see
an error message if you try to enter anything else.
Any such reassociation of a directory shortcut is temporary.
Directory shortcuts are set back to the values specified in the
Configuration File if you restart the program or reload the Con‐
figuration File (Default: Control-r).
Program Memories
If you've used GUIs before, you're probably familiar with the idea of a
program "Clipboard" - a temporary holding area which is used when cut‐
ting, copying, and pasting files. This is a good idea, but has several
limitations. First, most systems only have a single clipboard. It
would be mighty handy to have muliple Clipboard-like storage areas for
keeping track of several different operations at once. Secondly, when
you copy or paste something to a conventional Clipboard, its old con‐
tents get overwritten. There is no way to keep appending items to the
Clipboard. Finally, items usually can only be cut or copied to the
Clipboard from the current directory. It would be nice if we could not
only keep adding things to the Clipboard, but be able to do so as we
navigate around the filesystem.
twander addresses these concerns by means of 12 separate "Program Memo‐
ries". As you use twander, you can add (append) the names of any
directories or files in the currently viewed directory by selecting
them and then using the appropriate twander MEMSETx key (see below).
To take advantage of this feature, you write Command Definitions (or
manually issue a command via the RUNCMD key) which reference the con‐
tents of a Program Memory using one of the [MEMx] Built-In Variables.
(See the section below on entitled, Program Memory Built-Ins for more
details in how to apply Program Memories).
twander provides key combinations for selectively setting and clearing
particular Program Memories as well as a key combination for clearing
all Program Memories in a single keystroke:
Clear Selected Program Memory (MEMCLR1 - MEMCLR12)
Control-F1 ... Control-F12
Clear (empty) the selected Program Memory.
Clear All Program Memories (MEMCLRALL)
Control-m
Clear (empty) all 12 Program Memories at once.
Set Selected Program Memory (MEMSET1 - MEMSET12)
Alt-F1 ... Alt-F12
Append the the full path names of the currently selected files
and directories to the Program Memory desired.
Sorting Options
twander provides a variety of ways to sort the display. These can be
selected with either a keystroke or from the Sorting Menu (see below).
The meaning of the sort depends on whether or not you are in Drive List
View (see ADVANCED WINDOWS FEATURES below). The table below summarizes
the keys associated with sorting and their meaning in the two possible
views:
Program
Function Sort Order In Sort Order In
Key Name Normal View Drive List View
--------------------------------------
Shift-F10 SORTBYNONE No Sort No Sort
Shift-F1 SORTBYPERMS Permissions Label/Share String
Shift-F2 SORTBYLINKS Links Drive Type
Shift-F3 SORTBYOWNER Owner Free Space
Shift-F4 SORTBYGROUP Group Total Space
Shift-F5 SORTBYLENGTH Length Drive Letter
Shift-F6 SORTBYTIME Time Ignored
Shift-F7 SORTBYNAME Name Ignored
Shift-F11 SORTREV Reverse Order Reverse Order
Shift-F12 SORTSEP Separate Dirs Ignored
An easy way to remember these is that the function key number for the
primary sort keys corresponds to the column position of the key in a
detailed display. For instance, Shift-F1 sorts by column 1, Shift-F2
by column 2, and so forth.
These sorting options are available whether or not details are cur‐
rently available. For example, you can toggle details off, but still
sort by one of the now invisible details such as Owner, Length, and so
on.
SORTREV reverses the order of the sort.
SORTSEP toggles whether or not directories and files should be grouped
separately or displayed in absolute sort order. If enabled, directo‐
ries will be displayed first, then files. If the sort is reversed via
SORTREV, and SORTSEP is enabled, the directories will appear after the
files, sorted by whatever sort key has been chosen. SORTSEP is not
meaningful in Drive List View and is ignored.
You'll find the currently selected sorting options displayed in the
program title bar.
Wildcard Features
Although twander provides a very rich set of keyboard and mouse selec‐
tion commands, selecting a group of files out of list of hundreds or
thousands in a large directory can be tedious. If the files/directo‐
ries you want to select have some lexical commonality in their names OR
details you can have twander select them for you using so-called "Regu‐
lar Expressions".
You can do this in one of two ways. A wildcard "filter" only displays
files that match the specified regular expression. A wildcard "selec‐
tion" selects (highlights) the matching entries from the currently dis‐
played list. The general idea is to use filters to limit the number of
files you'll even see in the twander interface and then optionally
choose from among them with a wildcard-based selection.
For example, suppose you initiate a wildcard-based selection (SELWILD)
with the text, tar. This would select every file or directory in the
current display where the string "tar" appeared anywhere on the line
for that file/directory. This is very important: Wildcard matching
takes place anywhere on the visible line. So, if you have details
turned on, the match can occur anywhere on the permissions, links,
group, owner, and so on. Obviously, if you have details turned off,
the match can only occur on the name of the file or directory since
that's all that is visible.
This is a purposeful design decision because it allows you to make
selections on more than just the name. Say you enter the following in
the FILTERWILD dialog:
drwx------
twander would display only the entries that are directories with no
permissions enabled for group or world users.
The matching string above could also filter/select other entries (not
having the permissions just described), if say, this string appeared in
their name ... a rather unlikely scenario, but not impossible. If we
want to get real specific about which entries we want selected, we need
to enter a "regular expression" in the wildcard dialog. Regular
expressions are a far more powerful pattern-matching tool than simple
text strings and will allow you to do some fairly amazing selections.
For example, this regular expression selects all entries which contain
a string beginning with "Ju" followed by any other character, a single
space, and ending in "0":
Ju. 0
So, for instance, this would select files with date details (or names,
or anything else on the line...) like "Jun 01", "Jul 03", and "Jul 09".
No matter what you specify, a literal matching string or a regular
expression, the ".." entry of the currently viewed directory is never
selected for wildcard processing. This is a "special" entry that is
always present regardless of filtering and never selected with wild‐
card-based selections.
Notice that these regular expressions are not the same thing as the
filename "globbing" wildcards commonly used with Unix and Windows
shells. If you enter constructs like "*.txt" or "*.tar.gz", you will
not get the results you expect. In fact, these specific examples will
cause twander to grumble and present a warning message.
For an excellent tutorial on Python-compliant regular expressions, see:
http://www.amk.ca/python/howto/regex/
By default, these wildcarding tools will select an entry when your reg‐
ular expression matches anything on the displayed line. This allows
you to make selections based on any visible column of information.
This "match anywhere on the line" semantic is possible because twander
automatically massages the regular expression you provide to make "any
match on the line" true. There may be times when you want to provide
very specific regular expression definitions which seek a match at spe‐
cific locations. In that case, you can prevent the program from fid‐
dling with your regular expression, by beginning it with the double-
quote (") character. twander understands this to mean that your regu‐
lar expression is to be treated literally without modification. (It
only throws away this leading escape character.)
Suppose we changed our example above slightly and used this regular
expression:
"^drwx------
Now twander would select only the directories without any group and
world access because:
· The leading double-quote (") forces literal interpretation of the
regular expression - i.e. It turns off "match anywhere" semantics
as just described.
· The carat (^) at the beginning of the actual regular expression
"anchors" the match to the start of the line. For a match to be
declared (and for twander to select an item) the regular expression
must be satisfied at the beginning-of-line.
Because regular expressions can get complicated and tedious to type in,
any such expression you use is saved in a history available via the
Filter and Select Menus (see below). There is also provision for pre-
defining frequently used wildcards in your Configuration File (see sec‐
tion below on WILDFILTER= and WILDSELECT= configuration statements) so
you don't have to type them in manually each time you start the program
- you can just select them from the relevant menu.
A few points to keep in mind when using wildcard features:
·
By default, wildcard matching is case-insensitive on Win32 systems
and case-sensitive everywhere else. This is because Windows sys‐
tems allow case in filenames and attributes, but it is not signifi‐
cant - i.e., The case of a filename or attribute is ignored on Win‐
dows systems. You can control this explicitly with the WILDNOCASE
configuration option. If you set WILDNOCASE=False, it will force
all wildcard filters and selections to be case-sensistive. Setting
it to True makes the wildcarding case-insensitive. This option is
available for both Unix and Win32 systems so you can set the behav‐
ior you like anywhere.
· If you escape a wildcard to force twander to treat it exactly as
you defined it, the case-sensitivity set by default or WILDNOCASE
is ignored. Escaped wildcards are always treated exactly as you
enter them and they are matched against the filename and/or details
exactly as they appear.
· Wildcard-based filters are applied against the entire contents of
the current directory to determine which files match and should be
displayed. But, wildcard-based selections are done against the
currently visible files. This is important if you do a filter and
then a selection wildcard. The first will select which files to
display. The second will select which ones to highlight from the
displayed list.
Display Files Matching A Regular Expression (FILTERWILD)
Control-equal
This will present you with a dialog to enter your regular
expression matching criteria described above. After you enter
it, twander will only display the files that match. The filter
is reset (to no filtering) when you manually referesh the direc‐
tory - with REFRESH (default: Control-l - or change directories.
Toggle Active Filter (TOGFILT)
Control-minus
Pressing this once "inverts" any filter currently active. It
means "show me the files that don't match the filtering regular
expression." Pressing it again returns the filter to its normal
meaning. This is handy when you want to display everything
except a group of files. You first filter for the files you
don't want and then press TOGFILT which will display everything
except these files.
Select Files Matching A Regular Expression ´Wildcards´ (SELWILD)
Control-\
This will present you with a dialog to enter your regular
expression matching criteria described above. After you enter
it, twander will select (highlight) the files that match.
You can also "invert" your selections by using the SELINV key
described previously. This is useful when you want to select
everything except a group of files. Select the ones you don't
want with a selection wildcard andthen press the SELINV key.
Selections remain in effect until you make another manual selec‐
tion, clear all selections, or run a command that forces a
directory refresh after it runs - i.e., Commands defined with a
leading "+".
Display Selection Wildcard Menu (MOUSEFILTERSEL)
Alt-Control-Middle-Mouse-Button
Display Selection Wildcard Menu (MOUSEWILDSEL)
Alt-Control-Right-Mouse-Button
(Note that on Windows you must press Alt then Control then the
mouse button for this to work. Windows appears to care deeply
about keystroke order.)
These keys popup a list near the current mouse cursor of any
previously used filtering or selection wildcards respectively.
Selecting one of the entries therein pops-up a dialog that
allows you to edit the wildcard before actually doing another
wildcard filter or selection. This allows use to modify previ‐
ous wildcards for new use.
Hiding Dotfiles
By convention on Unix and many other systems, files or directories
whose names begin with a dot ('.') are usually used as configuration
files (directories). Unless you specifically want to edit a configura‐
tion, you typically do little or nothing with these files. Since there
can be quite a few of them on a modern system, it's helpful to be able
to block them from view.
By default, dotfiles are not hidden, but this can be changed with the
HIDEDOTFILES configuration option.
By default, files or directories whose names begin with a period (".")
are considered dotfiles. You can change this dotfile "introducer"
string with the DOTFILE configuration option.
Toggle Dotfile Hiding (TOGHIDEDOT)
Control-9
This toggles dotfile hiding, on- and off. The program starts up
with dotfiles visible or hidden as defined by the HIDEDOTFILES
program option. Thereafter, TOGHIDEDOT can be used to make
these files and directories visible or not.
Unlike Wildcard Filters (which test the entire displayed line), dotfile
hiding is triggered only by the name of the file or directory.
If you change DOTFILE to some other string, be aware that the test to
see if a file (or directory) name starts with this string is case-sen‐
sitive. If you set DOTFILE to "De", it will not hide files starting
with "de", for example.
The current state of dotfile hiding is displayed in the window title
bar, immediately after the Filter information.
Note that even though you cannot see the files with this option
enabled, commands you write can still operate on these files. For
example, if you define a command that does something like:
c cleandot rm .*~
This command will remove any backup (~) files, whether or not you can
see them in the interface.
MENU OPTIONS
Although twander is primarily keyboard-oriented, several menu-based
features are also implemented to make the program more convenient to
use. These menus appear at the top of the twander display window,
above the directory listing.
Invoking A Menu
A menu can be invoked in one of several ways. You can click on it, you
can press its associated "Accelerator Key" combination, or you can use
the "Mouse Shortcut" to cause a copy of the menu to pop-up near the
mouse pointer. The Accelerator Keys are shown in parenthesis next to
the menu names below and the Mouse Shortcuts are similarly shown below
in square brackets. All menus have Accelerator Keys defined, but only
some menus have associated Mouse Shortcuts.
Detaching A Menu
The first item in each menu is a dashed line ("----") which indicates
that it is a "tearoff" menu. Clicking on the dashed line will detach
the menu from twander allowing it to be placed anywhere on screen.
Even when detatched, these menus remain current and in-sync with twan‐
der as it continues to run. You can also tear off multiple instances
of these menus if you'd like copies of them at several locations on the
screen simultaneously.
Managing The Size Of Dynamic Menus
A number of these menus have "dynamic" content - their content changes
as the program runs. For example, the Directory, History, Filter and
Select menus all keep some sort of "history" of what the program has
done. Their content thus grows longer as the program is used.
On Windows systems, if such menus grow too long to physically fit on
screen, up- and down- scrolling arrows automatically appear at the top-
and bottom of the menu respectively. This is not a feature of the Unix
Tk implementation, so menus which grow too large are simply truncated
to fit the screen on Unix-like systems.
There are two User-Settable Options options available to help you man‐
age the maximum size of dynamic menus (see the section below on the
Configuration File which explains how such options are actually set.
The MAXMENU option specifies the maximum number entries that will be
displayed in any dynamic menu. (twander internally tracks MAXMENUBUF
number of items for each dynamic menu.) This defaults to 32 as is
intended to keep the menu size reasonable.
If you set MAXMENU=0, it means you are disabling all dynamic menus. It
also means that no interactive dialog will "remember" your last manual
entry. For example, with MAXMENU set to 0, twander will not keep track
of your last manual entries for the CHANGEDIR, FILTERWILD, SELWILD, and
RUNCMD dialogs.
MAXMENUBUF specifies the size of the internal storage buffer for each
dynamic menu regardless of how many entries are actually displayed.
i.e. MAXMENUBUF determines how many dynamic events each menu tracks
internally regardless of how many are actually visible in the menu at
any moment in time. It defaults to 250 and probably never needs to be
changed. If you set MAXMENUBUF to be less than MAXMENU, then this
smaller value will determine the maximum size of the displayed menu.
Setting MAXMENUBUF to 0 is equivalent to setting MAXMENU to 0.
Commands Menu (Alt-c) [Right-Mouse-Button]
Every command defined in the Configuration File is listed in this menu
by its Command Name. The association Command Key is also shown in
parenthesis. Clicking on an item in this menu is the same as invoking
it from the keyboard by its Command Key. This is a convenient way to
invoke an infrequently used command whose Command Key you've forgotten.
It is also handy to confirm which commands are defined after you've
edited and reloaded the Configuration File. The commands are listed in
the order in which they are defined in the configuration file. This
allows most frequently used commands to appear at the top of the menu
by defining them first in the Configuration File. If no commands are
defined, either because the Configuration File contains no Command Def‐
initions or because the Configuration File cannot be opened for some
reason, the Commands Menu will be disabled (grayed out).
History Menu (Alt-h) [Shift-Control-Right-Mouse-Button]
twander keeps track of every command you attempt to execute, whether it
is an invocation of a Command Definition found in the Configuration
File or a manually entered command via the RUNCMD key. (default: Con‐
trol-z) This is done whether or not the command is successfully exe‐
cuted.
This feature provides a quick way to re-execute a command you've previ‐
ously run. When you select a command to run this way, a dialog box is
opened, giving you an opportunity to edit the command before running it
again.
One important point of clarification is in order here. If you run one
of the commands defined in your Configuration File, it is stored in the
History after all variable substitutions have been made. But, manually
entered commands are stored in the History literally as typed - i.e.,
Without variable substitution. This allows you easily reuse a manually
entered command in another directory or context. (Presumably, Command
Definitions in the Configuration File are written in such a way so as
to be useful across many different directories and contexts. Running
such a command again is simply a matter of pressing its associated let‐
ter key once more. By storing the resolved version of the command in
the History, you can see what the command actually did.)
The History Menu is emptied and grayed out when you press the CLRHIST
key. (default: Control-y)
Directories Menu (Alt-d) [Shift-Right-Mouse-Button]
twander keeps track of every directory visited. The previously
described command to move "Back" one directory allows directory naviga‐
tion in reverse traversal order - you can back up to where you started.
However, this feature "throws away" directories as it backs up, sort of
like an "undo" function.
The "Directories" menu provides a slightly different approach to the
same task. It keeps permanent track of every directory visited and
displays that list in sorted order. This provides another way to move
directly to a previously visited directory without having to manually
navigate to it again, back up to it, or name it explictly using the
Change Directory command.
Unless MAXMENU is set to 0, the Directory Menu shows the last MAXMENU
directories visited in alphabetically sorted order (unless you change
MAXMENUBUF to be smaller than MAXMENU). "Visited", in this case, is
stretching things a bit.
The Directory Menu is emptied and grayed out when you press the CLRHIST
key. (default: Control-y)
Shortcut Menu (Alt-u) [Alt-Control-Left-Mouse-Button]
This menu provides a way to access any of the Directory Shortcuts
defined in the Configuration File. It also provides a number of
"canned" navigation shortcuts to go up a directory, back a directory,
to the home directory, to the starting directory, and to the root
directory. On Windows systems using the Win32All extensions, there is
also a shortcut to the Drive List View.
Filter Menu (Alt-f) [Alt-Control-Middle-Mouse-Button]
(Note that on Windows you must press Alt then Control then the Middle-
Mouse-Button for this to work. Windows appears to care deeply about
keystroke order.)
This menu provides a list of all previously used filtering "wildcard"
regular expressions. Any regular expressions defined in the Configura‐
tion File (see below) using the "FILTERWILD = " statement will also
appear in this menu. This saves you the tedium of constantly having to
enter complex regular expression syntax every time you wish to do wild‐
card-based selections.
Selecting something from this menu brings up a dialog box which allows
you to edit the selected wildcard before using it.
Bear in mind that the size of the displayed menu is governed by the
MAXMENU and MAXMENUBUF Configuration File options (see below). i.e.,
Only the last MAXMENU number of wildcards are actually displayed on the
menu.
The Filter Menu is emptied and grayed out when you press the CLRHIST
key. (default: Control-y) This history is not cleared if the Configu‐
ration File is reloaded.
Select Menu (Alt-l) [Alt-Control-Right-Mouse-Button]
(Note that on Windows you must press Alt then Control then the Right-
Mouse-Button for this to work. Windows appears to care deeply about
keystroke order.)
This menu provides a list of all previously used selection "wildcard"
regular expressions. Any regular expressions defined in the Configura‐
tion File (see below) using the "SELECTWILD = " statement will also
appear in this menu. This saves you the tedium of constantly having to
enter complex regular expression syntax every time you wish to do wild‐
card-based selections.
Selecting something from this menu brings up a dialog box which allows
you to edit the selected wildcard before using it.
Bear in mind that the size of the displayed menu is governed by the
MAXMENU and MAXMENUBUF Configuration File options (see below). i.e.,
Only the last MAXMENU number of wildcards are actually displayed on the
menu.
The Select Menu is emptied and grayed out when you press the CLRHIST
key. (default: Control-y) This history is not cleared if the Configu‐
ration File is reloaded.
Sorting Menu (Alt-s) [Alt-Shift-Right-Mouse-Button]
(Note that on Windows you must press Alt then Shift then the Right-
Mouse-Button for this to work. Windows appears to care deeply about
keystroke order.)
This menu provides a way to select any of the available sorting
options. It is context-sensitive and will show entries appropriate to
what kind of "view" the program is currently displaying. That is, it
will show options which make sense for both "normal" view as well as
"Drive List View" (see the ADVANCED WINDOWS FEATURES section below).
You'll find the currently selected sorting options displayed in the
program title bar.
Help Menu (Alt-l) [No Mouse Shortcut]
This menu provides information about various internal settings of twan‐
der including Internal Program Variables, User-Settable Options, Key‐
board Assignments, User-Defined Variables, Command Definitions, and
Associations. It also has an About feature which provides version and
copyright information about the program.
For the most part, this help information should fit on screen easily.
However, very long Command Definitions will probably not fit on-screen.
In this case, if you are curious about just how twander is interpreting
your Command Definitions, invoke the program with the relevant debug
bit turned on and watch the output on stdout as twander runs.
THE twander CONFIGURATION FILE
Much of twanders flexibility comes from the fact that it is a macro-
programmable user interface. The program itself does little more than
provide a way to navigate around a filesystem. It must be configured
(programmed) to actually do something with the files you specify. This
is done via a "Configuration File". This file is also used to set Pro‐
gram Options and change keyboard assignments. Although the program
will run without a Configuration File present, it will warn you that it
is doing so with no commands defined.
LOCATION OF CONFIGURATION FILE
By default, the program expects to find configuration information in
$HOME/.twander (%HOME%\.twander on Windows) but you can override this
with the -c command line option. (Recommended for Windows systems - see
the section below entitled, INSTALLING twander )
Actually, twander can look in a number of places to find its Configura‐
tion File. It does this using the following scheme (in priority
order):
· If the -c argument was given on the command line, use this argument
for a Configuration File.
· If -c was not given on the command line, but the HOME environment
variable is set, look for the a Configuration File as $HOME/.twan‐
der.
· If the HOME environment variable is not set and a -c command line
argument was not provided, look for a file called ".twander" in the
directory from which twander was invoked.
CONFIGURATION FILE FORMATtwander Configuration Files consist of freeform lines of text. Each
line is considered independently - no configuration line may cross into
the next line. Whitespace is ignored within a line as are blank lines.
There are several possible legal lines in a twander Configuration File:
Comments
Program Option Statements
Key Binding Statements
Directory Shortcut Statements
Wildcard Statements
Variables And Command Definitions
Associations
Conditional Processing Statements
The Include Directive
(See the ".twander" file provided with the program distribution for
examples of valid configuration statements.)
Everything else is considered invalid. twander will respond with
errors or warnings as is appropriate anytime it encounters a problem in
a Configuration File. An error will cause the program to terminate,
but the program continues to run after a warning. For the most part,
twander tries to be forgiving and merely ignores invalid configuration
statements (after an appropriate warning). It only declares an error
when it cannot continue. This is true both when the program initially
loads as well as during any subsequent Configuration File reloads ini‐
tiated from the keyboard while running twander.
The following sections describe each of the valid Configuration File
entires in more detail.
Comments
A comment is begun with the "#" character which may be placed anywhere
on a line. Comments may appear freely within a Configuration File.
twander strictly ignores everything from the "#" to the end of the line
on which it appears without exception. This means that "#" cannot
occur anywhere within a User-Defined Variable Definition, Key Binding
Statement, or Command Definition (these are described below). Comments
can be placed on the same line to the right of such statements.
It is conceivable that the "#" character might be needed in the Command
String portion of a Command Definition. twander provides a Built-In
Variable, [HASH], for exactly this purpose. See the section below
entitled, Variables And Command Definitions, for a more complete
description.
Program Option Statements
Many of twanders internal program defaults can be overriden in the Con‐
figuration File using Program Option statements. These statements look
just like the User-Defined variables described later in this document
except twander recognizes the variable name as a Program Option rather
than an arbitrary variable. Program Option Statements thus take the
form:
Option Name = Option Value
The Option Name is case-sensitive and must be entered exactly as
described below. For instance, twander understands "AUTOREFRESH" as a
Program Option, but will treat "AutoRefresh" as a User-Defined Vari‐
able.
The Option Value is checked to make sure it conforms to the proper type
for this variable. The Type can be Boolean, Numeric, or String.
A Boolean Option must be assigned a value of True or False. These log‐
ical values can be in any case, so TRUE, TRue, and tRue all work.
A Numeric Option must be a number 0 or greater. Numbers can also be
entered in hexadecimal format: 0xNNN, where NNN is the numeric expres‐
sion in hex.
A String Option can be any string of characters. Quotation marks are
treated as part of the string! Do not include any quotation marks
unless you really want them to be assigned to the option in question
(almost never the case).
Furthermore, as described above, you cannot use the ´#´ symbol as part
of the string assignment because twander always treats this character
as the beginning of a comment no matter where it appears.
For consistency with other Configuration File entries, Program Option
Statements may have a blank Right Hand Side. Such statements are sim‐
ply ignored. This is convenient when you want to leave a placeholder
in your Configuration File but don't actually want to activate it at
the moment. However, be careful - depending on what precedes the
statement, you'll get different settings for the option in question.
For example:
# This effectively sets BCOLOR to its default value when
# the Configuration File is reloaded
BCOLOR =
# But this means the value of BCOLOR is set to red
BCOLOR = red
BCOLOR =
In other words, you should think of Program Option Statements with a
blank Right Hand Side as comments - present but ignored.
Other than this basic type-checking, twander does no further validation
of the Right Hand Side of a Program Option Statement. It is perfectly
possible to provide a RHS which passes twanders type validation but
which makes no sense whatsoever to the program. Entries like this
cause everything from a mild twander warning to a spectacular program
failure and Python traceback on stdout:
# A Nice Way To Clobber twander
BCOLOR = goo
The following sections document each available Program Option using
this general format:
Option-Name [Type] (Default Value)
ACTUALLENGTH [Boolean] (False)
By default, file sizes , total directory size (on the title
bar), and drive sizes in Win32 Drive List view are "normalized".
They are expressed in bytes, Kilobytes, Megabytes, or Gigabytes.
This keeps the display from getting cluttered with the longer
strings required to display the actual lengths in bytes. If you
want the program to display the actual lengths for these items
by default, set ACTUALLENGTH=True in your Configuration File.
You can also "toggle" between normalized and actual size display
with the TOGLENGTH key (default: Control-0).
ADAPTREFRESH [Boolean] (True)
Whenever a directory is read, the time to do so is tracked. If
that time is less than the current value of REFRESHINT - i.e.,
The directory read took less than REFRESHINT milliseconds to
complete - nothing special happens. But, if the actual direc‐
tory read time takes longer than REFRESHINT milliseconds, twan‐
der adjusts the value of REFRESHINT upwards. That way, you're
guaranteed to have time after the read completes to actually do
something.
This dynamic adjustment takes place on every directory read. If
you go to a slow directory and REFRESHINT gets dynamically
adjusted to, say, 25 seconds, when you go back to a
faster/smaller directory, REFRESHINT will be reset to its
default value. The changing value of REFRESHINT is not shown in
the program options help menu. The value there is the one set
by default or set in the Configuration File. Think of this as
the "base" value for REFRESHINT.
If ADAPTREFRESH is set to False, then adaptive refresh timing is
disabled and a directory refresh will be attempted every
REFRESHINT milliseconds.
AFTERCLEAR [Boolean] (True)
Tells twander to clear any selections in the GUI if a command
forces a display refresh after it completes. (See the AFTERWAIT
and Forcing Display Updates In Command Definitions sections
below). This is done because a command that forces a display
update is probably changing the content of the current directory
(otherwise, why bother with the update?), and the current selec‐
tions may no longer be relevant.
Setting AFTERCLEAR to False, will leave the current selections
alone after doing a command with a forced update.
AFTERWAIT [Numeric] (1)
It is possible to define commands so that a display refresh is
forced after a command is invoked (see the section below enti‐
tled, Forcing Display Updates In Command Definitions ). The
AFTERWAIT option tells twander how long to wait after the com‐
mand has been initiated before actually doing the refresh. The
idea here is to give the command some time to complete before
updating the display.
AUTOREFRESH [Boolean] (True)
By default, twander regularly re-reads the current directory to
refresh the display with any changes. If you are running on a
very slow machine or slow connection between the X-Windows
server and client, set this option to False. You can manually
force an update at any time using the REFRESH key. (default:
Control-l)
BCOLOR [String] (Black)
Selects the main display Background Color.
CMDMENUSORT [Boolean] (False)
By default, twander populates the command menu on the menu bar
(and the popup command menu) with commands in the order in which
they are defined in the Configuration File. This was done so
that you could define the most important or most frequently used
commands first and they would thus conveniently appear at the
top of the menu list. However, if you prefer your command list
to be sorted, set the CMDMENUSORT option to True.
Note that the Command Definitions help menu ignores CMDMENUSORT
and is always presented in sorted order.
CMDSHELL [String] ()
This option is primarily intended for people running twander on
Unix-like operating systems like FreeBSD and Linux. As
described in the GOTCHAS section below, running a command line
program or script requires some extra effort if you want to see
the results presented in a GUI window. Typically, you need to
run these commands in some kind of ´xterm´ context so that the
results will be visible, possibly using a shell as well. So,
it's common to see Command Definitions like:
x MyCommand xterm -l -e bash -c 'stuff-for-my-command'
In fact, on Unix, the need for this idiom is so common, it's
best to define some variables for this. If you look in the
example ´.twander´ Configuration File provided in the program
distribution, you'll see something like (comments removed):
SHELL = bash -c
VSHELL = [XTERM] [SHELL]
XTERM = xterm -fn 9x15 -l -e
Now the Command Definition above becomes:
x MyCommand [VSHELL] 'stuff-for-my-command'
That's all well and good for Command Definitions, but what hap‐
pens when you want to manually enter a command via the RUNCMD
key? (default: Control-z) You have to manually enter the gob‐
bledy-gook above, or at least start your command with [VSHELL]
(since RUNCMD understands variable references).
The CMDSHELL option is a way to automate this. You can assign
it to any literal text. That text will be automatically
prepended to any command you enter manually. In this case you
could do either of the following in the Configuration File:
CMDSHELL = xterm -l -e bash -c
- or -
CMDSHELL = [VSHELL] # Assuming VSHELL is defined previously
Now every time you enter a command, this will be placed in front
of your text before command execution commences.
To disable CMDSHELL operation permanently, just remove the
statement above from your Configuration File. If you want to
leave it in as a placeholder, but deactivate CMDSHELL, use the
following statement:
CMDSHELL =
You also may want to occasionally use RUNCMD to do something
without CMDSHELL processing, even though that feature has been
defined in the Configuration File. You can disable CMDSHELL
operation on a per-RUNCMD basis. Just begin your entering your
command with the double-quote (") character. twander under‐
stands this to "escape" CMDSHELL processing.
As a general matter, CMDSHELL allows you to prepend anything you
like before a manually entered command - literal text, refer‐
ences to variables, or even the name of a script the system will
use to execute your command. Whatever value you use for CMD‐
SHELL will appear in the Command Menu history for each manually
initiated command which used this feature - i.e., All the manual
commands that did not escape the feature.
DEBUGLEVEL [Numeric] (0)
This is another way to set the debugging level you desire (the
other way being the -d command line argument). For example, say
you want to always dump the current Command Definitions to std‐
out when the program starts - perhaps you want to redirect this
output to a file or printer. Just add this line to your Config‐
uration File:
DEBUGLEVEL = 0x004
DEFAULTSEP [String] (==>)
This is the string that separates the prompting text and the
default response in {PROMPT: ...} and {YESNO: ...} Built-In
Variables. You may change this to any string you like, though
doing so is not recommended. Changing DEFAULTSEP will require
you to edit any Configuration Files that use these Built-Ins
with default responses. In no case should the delimiter string
include any of the characters, [ ]{ } since these are used as
delimiters in the twander configuration language.
DOTFILE [String] (.)
It is a convention on Unix (and other systems) that files or
directories whose names begin with a period are program configu‐
ration files (directories). twander has the ability to hide
these so-called "dotfiles". (See the section above entitled Hid‐
ing Dotfiles for the details.) twander treats any file or
directory whose name begins with the string defined by DOTFILE
as a dotfile for this purpose.
For example, if you set DOTFILE=Xyz, all files or directories
whose names begin with "Xyz", will be hidden when you tell twan‐
der to hide dotfiles. Notice that if you change this option
from its default, you may use any string to be the dotfile
"introducer", but it is always treated with case-sensitivity.
For instance, in our example, files beginning with "XYZ" would
not be hidden.
FCOLOR [String] (green)
Selects the main display Foreground (Text) Color.
FNAME [String] (Courier)
Selects the main display Font Name.
FSZ [Numeric] (12)
Selects the main display Font Size.
FWT [String] (bold)
Selects the main display Font Weight. This can be assigned to:
normal, bold, italic, or underlined. Depending on your system,
other values may also be possible.
FORCEUNIXPATH [Boolean] (False)
Ordinarily, Built-In Variables and Program Memory References in
a command definition are replaced with strings that list one or
more files and/or directories. When this substitution is made
at runtime, these strings contain the path separator character
appropriate for the underlying operating system ("/" for Unix
and "\" for Windows).
If you set FORCEUNIXPATH to True, twander will always use the
Unix path separator character("/") in these substitutions.
This option is primarily useful when writing command definitions
with Unix tools under Windows (such as cygwin) that are fussy
about path separator conventions.
This option is only relevant on Windows systems. It is ignored
on other operating systems.
HBCOLOR [String] (lightgreen)
Selects the help menu Background Color.
HEIGHT [Numeric] (600)
Initial vertical size of the twander window in pixels.
HFCOLOR [String] (black)
Selects the help menu Foreground (Text) Color.
HFNAME [String] (Courier)
Selects the help menu Font Name.
HFSZ [Numeric] (10)
Selects the help menu Font Size.
HFWT [String] (italic)
This selects the help menu Font Weight.
HIDEDOTFILES [Boolean] (False)
Sets whether the program hides "dotfiles" by default. (See pre‐
vious section entitled Hiding Dotfiles for the details of this
feature.) This value can be toggled with the TOGHIDEDOT
(default: Control-9) key binding.
INVERTFILTER [Boolean] (False)
Invert wildcard filtering. That is, display the entries that do
not match the wildcard filtering criteria. You can preset this
in the Configuration File as you wish, but the more usual way to
change it is via the TOGFILT (default: Control-minus) key bind‐
ing.
ISODATE [Boolean] (False)
Set this to True to display file/directory date and time in ISO
8601 format instead of the default US localized format.
MAXMENU [Numeric] (32)
Maximum number of entries to display in any dynamic menu. This
keeps the menu size reasonable. Internally, twander keeps track
of way more than this number of dynamic entiries (see the MAX‐
MENUBUF option below).
MAXMENUBUF [Numeric] (250)
Maximum number of items twander tracks internally for each
dynamic menu. This value need normally not be changed. It is
present only to bound how much memory twander consumes for this
task.
MAXNESTING [Numeric] (32)
Number of times a Command Definition is processed to dereference
all variables. For example, suppose you have this:
FOO = bax
BAM = x[FOO]
x mycmd [BAM] [SELECTION]
When you press the x key, the twander command interpreter has to
process the line repeatedly until all variables are resolved:
[BAM] [SELECTION] -> x[FOO] [SELECTION]
x[FOO] [SELECTION] -> xbax [SELECTION]
xbax [SELECTION] -> xbax selected-item
So, in this case, it took 3 iterations to do this. MAXNESTING
merely sets the maximum number of times this is permitted. We
have to do this to stop runaway definitions like this:
FOO = x[FOO]
This kind of construct will cause twander to iterate MAXNESTING
number of times and then give up with a warning about exeeding
the nesting (dereferencing) limit.
A 32 iteration limit should be plenty for any reasonable Command
Definitions. If you set MAXNESTING to 0, twander will not allow
any variable dereferencing, including the Built-In Variables.
This is probably not what you want.
MBARCOL [String] (beige)
Selects the Menu Bar color.
MBCOLOR [String] (beige)
Selects the menu Background Color.
MFCOLOR [String] (black)
Selects the menu Foreground (text) Color.
MFNAME [String] (Courier)
Selects the menu Font Name.
MFSZ [Numeric] (12)
Selects the menu Font Size.
MFWT [String] (bold)
Selects the menu Font Weight.
NODETAILS [Boolean] (False)
Prevents details from ever being displayed.
NONAVIGATE [Boolean] (False)
Prevents the user from navigating out of the starting directory.
Command Definitions and commands initiated manually via RUNCMD
(default: Control-z) can still "see" other directories, the user
just cannot move elsewhere with any of the twander navigation
commands.
The NODETAILS and NONAVIGATE commands are not security features.
They can easily be defeated by editing the Configuration File.
They exist to make it easy for you to create ´twander' configu‐
rations for technically unsophisticated users.
Say you want to define a few simple commands for your boss to
use which won't challenge his or her feeble managerial mind ;)
By defining these commands and setting both NODETAILS and NONAV‐
IGATE to TRUE, you really limit what can be done with twander.
They can't wander off into other directories and get lost, or
worse yet, clobber files they don't understand. There are no
details to confuse them. Your instructions for using the pro‐
gram thus become, "Select the files you're interested in and
press P to print them, M to mail them to Headquarters.." and so
on.
Again, these are NOT security features. Anyone with even very
modest technical skills can thwart these limitations. But, it
is suprising just how effective these can be in simplifying life
for technically challenged users.
QUOTECHAR [String] (double-quote symbol)
As described below, twander ordinarily quotes most Built-In
Variables as it replaces them during command processing. This
is useful because modern operating systems allow file and direc‐
tory names to have spaces in them. Such names must be quoted
for most programs to understand them as a single entity on a
command line.
By default, the double-quote char is used for this purpose. You
can suppress quote processing by using the -t command line argu‐
ment. This does nothing more than set QUOTECHAR to an empty
string. Unfortunately, since the RHS of a Program Option State‐
ment cannot be blank, you cannot disable quoting with this
option. However, you can set the quotation character to be any‐
thing else you like, such as a single-quote. In fact, you can
set QUOTECHAR to any string of characters you like and they will
faithfully be used on either side of a Built-In Variable
replacement.
REFRESHINT [Numeric] (5000)
Nominal time in milliseconds between automatic directory
refreshes (if AUTOREFRESH is True). This time is really nominal
and should not be used with any accurate timing in mind.
REFRESHINT=8000 says that the refresh interval will be nominally
8 seconds (and certainly more than the default of 5 seconds),
but it can be off this nominal value by quite a bit.
If you run twander on a slow system (or have a slow link between
X-Client and X-Server) you might want to increase this value
substantially. You can get into the situtation where just as
one refresh completes, its time to do the next one, and the
twander will seem really sluggish and unresponsive. By length‐
ening the time between automatic updates, the amount of unre‐
sponsive behavior is reduced. Of course, this also means that
any changes in the currently viewed directory will also take
longer to appear in the twander display.
SCALEPRECISION [Numeric] (1)
This specifies the number of digits of precision to display when
scaling file lengths (i.e., when ACTUALENGTH is set or toggled
to False). SCALEPRECISION sets how many digits to the right of
the decimal point to display in the scaled length. Notice that
this does not do proper rounding and thus the rightmost digit
can be off by -1.
SORTBYFIELD [String] (Name)
Specifies which field is to be used as the sort key. May be one
of the fields below under "Sort Key" (case-insensitive). The
equivalent field name for Drive List View (see ADVANCED WINDOWS
FEATURES section below) is shown in the second column, however
these may not be used as arguments for SORTBYFIELD. For exam‐
ple, if you plan to start the program in Drive List View and
want to sort by Drive Type, use: SORTBYFIELD=Links.
Equivalent
Sort Key Drive List View Field
-----------------------------
No Sort No Sort
Permissions Label/Share String
Links Drive Type
Owner Free Space
Group Total Space
Length Drive Letter
Time Drive Letter
Name Drive Letter
SORTREVERSE [Boolean] (False)
Specifies whether to reverse the sort order or not. If True and
SORTSEPARATE is also True, then the directory list will appear
at the end of the display in addition to being reverse ordered.
SORTSEPARATE [Boolean] (True)
Determines whether directories and files should be separated or
mingled in absolute sort order in the display. By default, they
are separated with directories sorted according to SORTBYFIELD
order but appearing before any files in the display.
This option is ignored in Drive List View.
STARTDIR [String] (Directory In Which Program Started)
This allows you to force a starting directory of your choice no
matter where the program actually is launched. This is useful
for day-to-day operation - perhaps you always want to start in
your home directory. STARTDIR is also handy in tandem with the
NODETAILS and NONAVIGATE options to force a user to the only
directory which they should be using.
STARTX [Numeric] (0)
Initial horizontal offset of the twander window in pixels.
STARTY [Numeric] (0)
Initial vertical offset of the twander window in pixels.
SYMDIR [Boolean] (True)
This option causes symbolic links that point to directories to
be treated as directories for purposes of sorting. This is rel‐
evant when "separated" sorting is selected - i.e., When the
directories are sorted separately from files. If SYMDIR is set
to False, then symbolic links will be sorted as files, regard‐
less of what the link points to. This option can be set in the
Configuration file or toggled from the keyboard with the
TOGSYMDIR (default: Control-~) key binding. The status of this
variable is displayed on the title bar in the "Symlinks:" field
as either a "D" or "F" for directory and file sorting respec‐
tively.
SYMEXPAND [Boolean] (True)
When displaying symbolic links, twander ordinarily shows both
the link name and its target. If you set SYMEXPAND=False, only
the name of the symbolic link, not its target will be shown.
This effectively causes a symbolic link to be displayed like any
other file or directory. This option can be set in the Configu‐
ration file or toggled from the keyboard with the TOGSYMEXPAND
(default: Control-!) key binding. The title bar status field,
"Symlinks:" will display an "E" if this option is True.
SYMRESOLV [Boolean] (False)
twander ordinarily displays symbolic link targets as they were
defined. That is, targets that were defined relative to the
current (or some other) directory, or targets that point to
other symbolic links will not be "resolved" to show their abso‐
lute path. Instead, the path as defined when the symbolic link
was created will be shown. Setting SYMRESOLV=True will cause
the absolute path of symbolic link targets to be displayed.
This option can be set in the Configuration file or toggled from
the keyboard with the TOGSYMRESOLV (default: Control-@) key
binding. If you toggle this option with TOGSYMRESOLV, it
implies you want to see symbolic link targets in some form
(either in resolved or unresolved form), so this keyboard action
will also force SYMEXPAND to be True. The title bar status
field, "Symlinks:" will display an "R" if this option is True.
USETHREADS [Boolean] (False)
twander defaults to using normal "heavy weight" processes for
running commands on Unix. Many Unix implementations also sup‐
port a "threaded" process model. Setting USETHREADS to True on
such systems will cause twander to use threads, rather than pro‐
cesses to launch user-defined commands. There are some known
issues with thread-based operations (hence the reason this
option defaults to False). These are discussed in the GOTCHAS
section below.
This option applies only to Unix-like operating systems. Win‐
dows commands are always run as a thread - this is the only
process model Windows supports..
USEWIN32ALL [Boolean] (True)
Windows only. If ´win32all´ is installed, determines whether
its features should be used (see section below entitled,
ADVANCED WINDOWS FEATURES for details).
Normally, this option should be left alone. However, if you
have ´win32all´ installed on your system for some other reason,
but don't want it used by twander, set this option to False.
The main reason to do this would be on a slow machine with very
large directories. The advanced features of ´win32all´ come at
a computational price. This is especially noticeable when it is
computing the attributes, ownership, and size in a directory
with hundreds (or more) of entries. Typically, you would just
use the TOGWIN32ALL key (default: Control-w) to temporarily dis‐
able these features before entering such a directory. However,
if your starting directory is in this category, setting
USEWIN32ALL=False might not be a bad idea.
WARN [Boolean] (True)
Determines whether interactive warnings should be displayed as
twander encounters them (while parsing a Configuration File or
just in normal execution).
Setting this option to False is the same thing as using the -q
command line option with one important difference: The Configu‐
ration File is parsed before the command line is parsed. Even
if you have -q on the command line (or in the TWANDER environ‐
ment variable), if there is an error in your Configuration File,
you will see warning messages at program startup time. Putting
WARN=False at the top of your Configuration File will suppress
this.
It is not recommended that you operate normally with the -q flag
or with WARN=False. twander is pretty forgiving in most cases
and when it does warn you about something, there is a good rea‐
son for it - you probably want to know what the problem is.
WIDTH [Numeric] (800)
Initial horizontal size of the twander window in pixels.
WILDNOCASE [Boolean] (True On Win32 / False Elsewhere)
Set's whether or not case is significant in wildcard filtering
and selection. If True, case is ignored, if False, case is sig‐
nificant in these wildcard operations.
A few general notes about Program Options are worth mentioning here:
· You can set the same option multiple times in a single Configura‐
tion File - twander pays no attention. However, only the last (the
one nearest the end of the file) instance of that Program Option
Statement actually takes effect. This is handy if you want to tem‐
porarily change something without modifying your existing configu‐
ration. Just add your temporary change at the end of the file.
When you're done with it, just remove it. No need to edit and re-
edit your preferred configuration...
· The font colors, weights, and sizes available for your use will
vary somewhat by system. For instance, Windows TrueType fonts are
effectively available in every size and weight. On the other hand,
most Unix-like systems have a more limited palette of fonts and
colors with which to work. Most systems should support obvious
color names like, red, white, blue, yellow, beige, and so on. Many
also support colors like lightgreen, lightblue, etc. At a minimum,
you should be able to use normal, bold, italic, and underline for
font weights.
Most systems attempt some kind of "best fit" font matching. If you
specify a font size/weight/name that does not exist, the system
will try to find what it thinks is the closest match. This is usu‐
ally ugly, so try to specify font information for things that actu‐
ally exist on your system.
If your setting in the Configuration File seems not to work, take a
look at the command window in which you started twander (or start
it from one manually, if you're using a GUI shortcut to start it).
Attempts to use unavailable colors and weights will cause
Python/Tkinter to dump traceback information on stdout.
· Although you can use proportionally spaced fonts with twander, the
result is pretty ugly. twander assumes a fixed width font when it
calculates display formatting. Variable-width fonts will cause
your display to be ragged and hard to read.
· If you set MAXMENU or MAXMENUBUF to 0, it disables both dynamic
menu content and of the last manual entry in the dialogs associated
with CHANGEDIR (default: Control-x), FILTERWILD (default: Con‐
trol-=), SELWILD (default: Control-\), and RUNCMD (default: Con‐
trol-z).
· Changing MAXMENU and then reloading the Configuration File only
changes the number of items visible on the various dynamic menus.
twander actually keeps track of more than this internally (governed
by the MAXMENUBUF option).
Say MAXMENU is set to 4, but you've actually visited 20 different
directories and issued 30 commands. You'll only see 4 of each on
the associated menus. But, if you edit MAXMENU to now be 32 and
reload the Configuration File, you will see all 20 directories and
30 commands on their respective menus.
· At first glance, the ability to set QUOTECHAR to any arbitary
string may seem silly, but it actually has a purpose. As good as
the twander macro capability is, it is still a fairly simple lan‐
guage. Really complex tasks will need to be handed off to some
other scripting language (like Python!). It may be useful to
delimit Built-In Variables (which indicate your selections via the
twander interface) in such a way that your script knows where they
came from. So, say you set QUOTECHAR=+++ and you have a Command
Definition like this:
x mycmd MyPythonScript [DSELECTIONS] other stuff
When MyPythonScript runs, it can immediately tell which arguments
came from twander (the ones that are in the form +++dir+++ or
+++file+++) and which arguments are just other stuff.
You probably won't need this often, but its nice to have.
· STARTX and STARTY are relative to the (0,0) origin that Tk uses for
window placement. In High-School algebra most of us got used to
seeing (0,0) in the lower-left corner of a graph. Tk has a rather
different view of this and STARTX and STARTY are relative to the
upper-left corner of the screen.
Key Binding Statements
No program that runs in many operating environments can satisfy every‐
one's (anyone's!) idea of what the "correct" key bindings should be.
An emacs user, vi user, BSD user, and Windows user are going to differ
considerably on what keys should be bound to what feature. twander
ships from the factory with a set of default key bindings, but it also
provides a mechanism for changing these bindings via entries in the
Configuration File.
This feature is available only for Keyboard Assignments. Mouse Button
Assignments may not be changed by the user. An attempt to do so in the
Configuration File will cause twander to display a warning and ignore
the offending line.
It is not difficult to override the default keyboard bindings by adding
entries in the Configuration File. Doing so requires some familiarity
with how Tkinter names keystrokes. Good resources for learning this
exist abundantly on the Internet, among them:
http://www.pythonware.com/library/tkinter/introduction/index.htm
http://www.nmt.edu/tcc/help/pubs/lang.html
http://www.cs.mcgill.ca/~hv/classes/MS/TkinterPres/
(As an aside - Tkinter is nothing more than a Python interface to the
Tcl/Tk windowing system. The "real" naming conventions for keystokes
can be found in the many sources of Tk documentation, both in print and
on the Internet.)
Keyboard binding assignments look just like variable definitions in the
Configuration File. (The twander Configuration File parser automati‐
cally distinguishes between Key Binding Statements and Variable Defini‐
tions or other legitimate statements. This means you can never use one
of the program function names as one of your own variable names.) Key
Binding Statements thus take the form:
Program Function Name = Tkinter Keystroke Name
Changing the default bindings is therefore nothing more than a matter
of assigning the appropriate Program Function Name (found in parenthe‐
sis next to the description in the default descriptions above) to the
desired keystroke.
Examples of all the default key bindings are shown as comments in the
".twander" example Configuration File supplied in the program distribu‐
tion. The easiest way to rebind a particular function is to copy the
relevant line, uncomment the copy, and change the right side of the
assignment to the new key you'd like to use.
It is important to observe several rules when rebinding keys:
· It is best if keyboard navigation commands are all Control or Func‐
tion keys. If you assign a navigation or selection function to a
single keystroke, it may conflict with a user-defined command. If
you assign it to a keypad/special key it may conflict with that
key's normal GUI behavior.
· The Tkinter keynames should placed on the right side of the "="
symbol without any quotation marks.
# Incorrect
QUITPROG = '<F3>'
# Correct
QUITPROG = <F3>
· The Program Function Name variables (the left side of the assign‐
ment) may not be used as names for your own user-defined variables
elsewhere in the Configuration File. In fact, twander will never
even recognize such an attempt. For example, suppose you try to do
this:
QUITPROG = something-or-other
Because you want to be able to reference [QUITPROG] in a subsequent
Command Definition. twander will actually interpret this as just
another key binding command, in this case binding the program func‐
tion QUITPROG to "something-or-other" - probably not what you
intended. Moreover, if you have a Command String somewhere with
[QUITPROG] in it, twander will declare and error and abort because
it has no User-Defined variable of that name in its symbol table.
· When you're done making changes to the Configuration File, be sure
to either restart the program or reload the Configuration File to
assign the new bindings.
· Be aware that twander does no sanity testing on the assignments you
change. If you assign a particular twander function to an illegal
or silly key string, the program will probably blow-up spectacu‐
larly. At the very least, that program feature will probably be
unusable, even if twander manages to run.
Directory Shortcut Statements
twander provides a mechanism for directly navigating into one of 12
frequently used directories. 12 keys, KDIRSC1 ... KDIRSC12 (default:
F1 ... F12) have been set aside for this purpose. Directory Shortcut
Statements are entries in the Configuration File which associate one of
these keys with a particular directory path. These statements are in
the form:
DIRSCxx = path
where, xx is a number from 1-12
So, for example, if you want to enter "C:\Documents And Settings" when
you press the F5 key, you would add this to your Configuration File:
DIRSC5 = c:\Documents And Settings
There are several subtleties to Directory Shortcuts you should under‐
stand:
· You can end the path with slash or not - twander will understand
the entry either way.
· If there is no path on the righthand side of a Directory Shortcut
Statement, this is the same as having no definition at all for that
key:
# This "undefines" shortcut #5
DIRSC5 =
· twander does absolutely no checking of what you enter to the right
of the equals sign. If you enter something silly for the shortcut
path, you will probably get a warning that the directory cannot be
opened when you try to run that shortcut.
· Keep the Program Function Names (KDIRSC1 ... KDIRSC12) which are
used for Key Binding, distinct in your thinking from the Directory
Shortcut Names (DIRSC1 ... DIRSC12) which are used for defining the
shortcuts.
· If you enter a Directory Shortcut Name that is invalid or out of
range - examples include, DIRSC01 and DIRSC13 - twander treats them
like a User-Defined Variable as described below.
· A Directory Shortcut Statement may make reference to user-defined,
environment, and execution variables.
~ = [$HOME]
DIRSC1 = [~]/Desktop # User-defined variable
DIRSC3 = [$HOME] # Environment variable
DIRSC5 = [`echo "/tmp"`] # Execution variable (but silly)
If you use one of these forms, it's up to you to make sure that
when when the variables are dereferenced (substituted), the result‐
ing string is the name of a directory. Be careful, you may not
spot a definition that is not a directory right away. Variables
are dereferenced at runtime not at the time the Configuration File
is read in. Therefore, Directory Shortcut assignments with vari‐
able references in them are shown literally in the Shortcut Menu.
twander cannot know what the value of the variable will be until
you actually press the relevant shortcut key.
Wildcard Statements
As discussed above, twander provides powerful regular expression-based
"wildcard" filtering and selection capabilities via the FILTERWILD
(default: Control-=) and SELWILD (default: Control-\) commands. These
regular expressions can be complex and tedious to enter by hand each
time you need them. You can pre-define frequently needed wildcard
strings in your Configuration File using the following statements:
WILDFILTER = regular-expression-string
WILDSELECT = regular-expression-string
The regular expression will then be pre-loaded into either the Filter
or Select Menus respectively when twander starts. This makes it easy
to use or modify complex wildcards over and over. You may place as
many of these as you like in your Configuration File. (Though the
menus will be limited to displaying MAXMENU number of items - see the
section above on Program Option Statements.)
Variables And Command Definitions
Most programs "ship from the factory" with a pre-defined set of fea‐
tures or commands. twander comes with no built-in commands! Instead,
it comes with a mechanism which allows you to specify your own Command
Definitions. By means of a simple and very powerful macro lanuage, you
"program" twander and equip it with commands of your own choosing. For
example, you might define commands to copy, delete, edit, and move the
files or directories you choose. Perhaps you have a specialized shell
script for doing backups. It's a simple matter to write a twander Com‐
mand Definition that will pass the names of the files and directories
you've selected to that backup script. You might combine this with
twander's Program Memory feature to keep a running list of the files
and directories you want to backup and then finally issue the backup
command when you're ready. Best of all, commands you define this way
are always a single keystroke. This means that once you've programmed
twander to suit your needs, actually using it is very fast and conve‐
nient.
Command Definitions are built out of literal text and may also have any
combination of several variable types: User-Defined Variables, Environ‐
ment Variables, Execution Variables, and Built-In Variables.
User-Defined Variables are variables you define in the configuration
file. They can hold any string of text you desire.
Environment Variables are set in the shell you use to invoke twander.
This makes it easy to write a generic command definition that acts
based on something set uniquely for each user in that user's environ‐
ment. You can only read, not change, Environment Variables in twander.
Execution Variables are set by running a program - pretty much any pro‐
gram will do. (Unix users will be familiar with this if they've ever
used shell "backtick" quoting.) This makes it easy to construct a
twander command that is defined in whole or in part by some external
program.
Built-In Variables are a set of variables defined by twander itself.
There are two general kinds of Built-Ins. The first kind are used to
let your command know (at runtime) which file or files you have cur‐
rently selected in the twander interface. The other kind of Built-Ins
are used to prompt you during command execution. There are also a few
other Built-Ins described below.
Just When Does A Variable Get Evaluated?
Before getting into the mechanics of variables and command definitions,
it's important to emphasize one point: Variables get "evaluated"
(read) when a command is actually run. Older versions of twander eval‐
uated variables at the time a configuration file was read. However, as
we'll see below, by waiting until the command is actually run to evalu‐
ate its variable references, we can do some nifty things.
User-Defined Variables And Environment Variables
User-Defined Variables are defined using the syntax:
Variable Name = Replacement String
Environment Variables are referenced using the syntax:
[$VARIABLE]
Say we have a configuration line like this,
EDITOR = emacs blah blah blah blah
Later on, when defining a command, instead of typing in "emacs blah
blah blah blah", you can just refer to the variable [EDITOR] - the
brackets indicate you are referring to a previously defined variable.
Similarly, suppose you have an environment variable called "EDITOR"
which indicates your preferred editing program. Our definition could
thus become:
EDITOR = [$EDITOR] blah blah blah blah
Why bother with this? Because it makes maintaining complex Configura‐
tion Files easier. If you look in the example ".twander" Configuration
File provided in the program distribution, you will see this is mighty
handy when setting up complex "xterm" sessions, for example.
Here are several other subtleties regarding User-Defined Variables:
· twander variable definitions are nothing more than a string substi‐
tution mechanism. Suppose you have a variable definition that
refers to another variable:
NewVar = somestring [OldVar]
It is important to realize that this only means: "If you encounter
the string ´[NewVar]´ in a subsequent Command Definition, replace
it with the string ´somestring [OldVar]´."
In other words, no evaluation of the right side of the expression
takes place when a variable is defined. Evaluation of a variable
only takes place when the variable is referenced (in the Command
String portion of a Command Definition) at the time the command is
run. The Command Definition parser will continue to dereference
variable names until they are all resolved or it has reached the
maximum nesting level (see next bullet).
· User-Defined Variables may be nested up to 32 levels deep (this
default can be changed via the MAXNESTING Program Option). You can
have constructs like:
Var1 = Foo
Var2 = Bar
FB = [Var1][Var2]
Later on (when defining some command) when twander runs into the
variable reference [FB], it will keep substituting variables until
all [...] references have been resolved or it hits the nesting
limit (The default is 32, but you can change it with the MAXNESTING
option). This limit has to be imposed to catch silly things like
this:
Var = a[Var]
This recursive definition is a no-no and will be cause twander to
generate an error while parsing the Configuration File and then
terminate.
Your variable definitions can also nest other kinds of variables
(Environment and Built-Ins). So, constructs like this are per‐
fectly OK:
Var1 = [$PAGER]
Var2 = command-arguments
V = [Var1] [Var2] [DSELECTION]
· In the example above, notice that since the right-hand side of
User-Defined Variables is literally replaced, we have to make sure
there is space between the various variable references. If we used
[Var1][Var2][DSELECTION] we would get one long string back instead
of a command with arguments and a list of selected items.
· Variable references are only significant on the right hand side of
an assignment statement:
Var1 = Foo
My[Var1] = bar
This does not create a variable called "MyFoo". It creates a vari‐
able called "My[Var1]" and sets its value to "bar". This is both
confusing and useless because you can never dereference this vari‐
able, because ...
· Variable references cannot be nested. Using our example above,
suppose we later want to get the value ("bar") of variable
"My[Var1]". That variable reference would look like this:
[My[Var1]] and this is not permitted. A variable reference may
only contain a text string, not references to other variables.
· Variables must be defined before they are referenced (in a Command
Definition). You can, however, include not-yet defined variable
name in another User-Variable Definition so long as all these vari‐
able are defined by the time they appear in a Command String. The
following is OK because all variables are defined by the time they
are actually needed:
Var1 = foo
Var2 = [Var3] # This is just a string substitution, not a reference
Var3 = bar
MyVar = [Var1][Var2]
# Now comes the Command Definition
# If we put this before the Variable Definitions above,
# it would be an error.
x mycommand [MyVar]
· Variable Names are case-sensitive - [EDITOR], [Editor], and [edi‐
tor] all refer to different variables.
· The "#" character cannot be used in either the variable name or the
replacement string since doing so begins a comment.
· The "=" is what separates the Variable Name from the replacement
string. Therefore, the "=" cannot ever be part of a Variable Name.
A Variable Name cannot begin with "$" (see next bullet). Other
than these minor restrictions, both Variable Names and Replacement
Characters can be any string of characters of any length. Good
judgment would suggest that Variable Names should be somewhat self-
descriptive and of reasonable length - i.e., Much shorter than the
replacement string!
· A Variable Name must never begin with "$". This is because a Com‐
mand Definition containing a string in the form [$something] is
understood by twander to be a reference to an Environment Variable,
named "something". If you do this:
$MYVAR = some-string
You will never be able to subsequently reference it because,
[$MYVAR] tells twander to look in the current environment, not its
own symbol table to resolve the reference. However, note that "$"
symbol may appear anywhere else but the first character of a vari‐
able name. So, for example, MY$VAR is fine.
· Unlike previous versions of twander, Variable Names may be rede‐
fined. This makes it more convenient to exploit the ability for
twander to process the contents of a Configuration File condition‐
ally (see the Conditional Processing Statements section below).
For example, you can set a variable to some default value, and then
override it if a condition is satisfied:
# Assume we're running on a Unix-like system
MyEditor = [$EDITOR]
# Override this if we're on Windows
.if [.OS] == nt
MyEditor = write
.endif
Execution Variables
Execution Variables are a special case of User-Defined Variables. How‐
ever, instead of setting a variable to some string of text, you tell
twander to run a program and set it's results to the variable:
TODAY = [`date`]
Now, suppose you define a command with [TODAY] in it somewhere. When
you later run that command, [TODAY] will be replaced by the output of
the "date" command. In other words, Execution Variables allow you to
run any external program you like, and have that program's output sub‐
stituted into the definition of a command. Several further points are
worth noting here.
· Notice that Execution Variables are delimited by backticks, not
single-quotes.
· If you have something like [`program`] in a Command Definition, it
will be replaced with any text that "program" produces as it runs.
That text will have any trailing newline stripped. Notice that
this is different that most twander variables that are evaluated
once when the Configuration File is first read in.
This is true wherever the execution variable appears - either as
the right-hand-side of a variable statement or explicitly inline
within a command definition. You can confirm this by looking at
the User-Defined Variables and Command Definitions help menus.
Anything referencing an execution variable will show the command to
be executed when the variable is actually referenced at command
invocation time.
· Suppose you want to populate an Execution Variable with a program
that returns multiple lines of text. You'll need to strip all the
newlines out of the output in that case. To do this, you can use a
second form of an Execution Variable: [`-program`]. The leading
minus sign tells twander to strip all newlines when doing the
replacement. For example, let's define a command that lists all
the files in the current directory:
a mycommand echo "[`-ls`]" # We need the double-quotes
# to make echo work right
Command Definitions
The heart of the twander configuration process is creating of one or
more Command Definitions. These definitions are the way user-defined
commands are added to a given instance of twander. A Command Defini‐
tion consists of three fields separated by whitespace:
Command-Key Command-Name Command-String
The Command Key is any single character which can be typed on the key‐
board. This is the key that will be used to invoke the command from
the keyboard. Command Keys are case-sensitive. If "m" is used as a
Command Key, "M" will not invoke that command. Command Keys must be
unique within a given Configuration File. If twander finds multiple
Command Definitions assigned to the same Command Key, it will associate
the last definition it finds with that Command Key. A Command Key can
never be "#" which is always understood to be the beginning of a com‐
ment.
The Command Name is a string of any length containing any characters.
This is the name of the command which is used to invoke the command
from the Command Menu. Command Names are case-sensitive ("command" and
"Command" are different names), but they are not required to be unique
within a given Configuration File. That is, two different Command Def‐
initions may have identical Command Names associated with them, though
this is not ordinarily recommended.
The Command String is any arbitrary string which is what twander actu‐
ally tries to execute when the command is invoked.
A Simple Command Definition
In its simplest form, a Command Definition looks like this:
# A simple Command Definition
m MyMore more somefile
This command can be invoked pressing the "m" key on the keyboard or
selecting the "MyMore" entry from the Command Menu - either directly
from the menu or from the Command Menu Pop-Up. No matter how it is
invoked, twander will then execute the command, "more somefile".
The problem is that this command as written actually will not give you
the result you'd like (...well, on X-Windows - is does work on Windows
as written). (For more details on why, see the GOTCHAS section below.)
It turns out that starting a non-GUI program like ´more´ in a new win‐
dow needs some extra work. What we want to do is run ´more´ inside a
copy of ´xterm´. Now our command looks like this:
# Our command setup to run as a GUI window
m MyMore xterm -l -e more somefile
Forcing Display Updates In Command Definitions
You are likely to define commands that change the contents of the cur‐
rently-viewed directory somehow. For instance, commands that rename,
create, or delete files in the current directory all have this effect.
When such a command is run, it means that the twander display is "out
of sync" with the actual disk contents until the next refresh cycle -
automatic if AUTORFRESH is enabled, manual otherwise.
Placing ´+´ symbol to the beginning of the Command String tells twander
that, when the command is run, a display refresh should be forced
afterwards. Not immediately afterwards, but AFTERWAIT seconds
(default: 1) later. Why? To give the command in question a chance to
complete before updating the display. For instance,
r removelogs +rm -f *log
This means that when the ´r´ key is pressed, the command, "rm -f *.log"
is run, and then, AFTERWAIT seconds later, twander will force a display
update. This happens regardless of the current AUTOREFRESH settings.
This feature is handy, but has some practical limitations. If this
feature updates the display before a command actually completes (i.e.,
the command you've launched takes longer than AFTERWAIT seconds to com‐
plete), the final state of the directory will not be displayed. The
idea here is to use this feature for "quicky" updates between more con‐
ventional display refreshes, whether via AUTOREFRESH or manually.
By default, anytime you run a command that uses this feature, any
selections in the GUI are cleared. This is because a forced update
presumably is required because the command changes something in the
current directory. In that case, the current selections may no longer
be relevant. If you wish to disable this behavior, set the AFTERCLEAR
program option to False.
User-Defined Variables In A Command String
The last example works quite nicely. But, we're probably going to end
up using the string "xterm -l -e" over and over again for any shell
commands we'd like to see run in a new window. Why not create a User-
Defined Variable for this string so we can simplify its use throughout
the whole Configuration File? Now, our command looks like this:
# Our command enhanced with a User-Defined Variable.
# Remember that the variable has to be defined *before*
# it is referenced.
XTERM = xterm -l -e # This defines the variable
m MyMore [XTERM] more somefile # And the command then uses it
Environment Variables In A Command String
This is all very nice, but we'd really like a command to be generic and
be easily used by a variety of users. Not everyone likes the "more"
program as a pager. In fact, on Unix-like systems there is an environ‐
ment variable ($PAGER) set by each user which names the paging program
that user prefers. We can refer to environment variables just like any
other variable as explained previously. Now our command looks like
this:
# Our command using both a User-Defined Variable and
# an Environment Variable to make it more general
XTERM = xterm -l -e
m MyMore [XTERM] [$PAGER] somefile
Execution Variables In A Command String
We can further extend the power of Command Definitions by using an Exe‐
cution Variable to define part of the command. Suppose we want a com‐
mand that will let us examine all the text files in the current direc‐
tory:
# Our command using User-Defined, Environment, and
# Execution Variables
XTERM = xterm -l -e
m MyMore [XTERM] [$PAGER] [`-ls *.txt`]
Built-In Variables In A Command String
It would also be really nice if the command applied to more than just a
single file called "somefile". The whole point of twander is to allow
you to use the GUI to select one or more directories and/or files and
have your Command Definitions make use of those selections. twander
uses a set of Built-In Variables to communicate the current directory
and user selections to the any commands you've defined. Built-In Vari‐
ables are referenced just like User-Defined Variables and Environment
Variables and may be inserted any appropriate place in the Command
String. In our example, we probably want the command to pickup what‐
ever item the user has selected via the GUI and examine that item with
our paging program. Now our command becomes:
# Our command in its most generic form using
# User-Defined, Environment, and Built-In Variables
XTERM = xterm -l -e
m MyMore [XTERM] [$PAGER] [DSELECTION]
The "DSELECTION" built-in is what communicates the currently selected
item from the GUI to your command when the command actually gets run.
Selection-Related Built-Ins
twander has a rich set of Built-In Variables for use in your Command
Definitions. The first group of these is used to convey your current
directory and items which you've selected to a Command Definition:
· [DIR]
[DIR] is replaced with the current directory twander is viewing.
· [DSELECTION]
[DSELECTION] is replaced with the full path name of the item cur‐
rently selected in the GUI. If more than one item is selected,
[DSELECTION] refers to the last item in the group (the bottom-most,
not the most recent item you selected).
· [DSELECTIONS]
[DSELECTIONS] is replaced with the full path name of all items cur‐
rently selected in the GUI.
· [SELECTION]
[SELECTION] is replaced with the name of the currently selected
item in the GUI. The path to that file is not included. As with
[DSELECTION], if more than one item is selected in the GUI, the
name of the last item in the group is returned for this variable.
· [SELECTIONS]
[SELECTIONS] is replaced with the names of all items currently
selected in the GUI. The path to those names is not included.
Prompting And Special-Purpose Built-Ins
There are also several special-purpose Built-In Variables which are
used for creating more powerful Command Definitions.
Note: The PROMPT and YESNO Built-Ins use {} as delimiters, not [].
· [HASH]
Because twander always recognizes the "#" as the beginning of a
comment, there is no direct way to include this character in a Com‐
mand String. It is conceivable that some commands (such as ´sed´)
need to make use of this character. The [HASH] built-in is pro‐
vided for this purpose. Anywhere it appears in the Command String,
it will be replaced with the "#" at command execution time. Unlike
all the other Built-In Variables, [HASH] is never quoted when it is
replaced in a Command String (regardless of whether the -t command
argument is used or how the QUOTECHAR Program Option is defined).
· {PROMPT:Prompt-String==>default}
{PROMPT:...} allows you to insert an interactive prompt for the
user anywhere you'd like in a Command String. The user is prompted
with the "Prompt String" and this variable is replaced with their
response. If they respond with nothing, it is interpreted as an
abort, and the command execution is terminated. This makes com‐
mands extremely powerful. For instance, say you want to create a
group copy command:
# Copy a group of items to a location set by
# the user at runtime
UnixCopy = cp -R
Win32Copy = copy
# Unix Version
c UnixCP [UnixCopy] [DSELECTIONS] {PROMPT:Enter Destination}
# Win32 Version
C Win32CP [Win32Copy] [DSELECTIONS] {PROMPT:Enter Destination}
You can also provide a default response to the question. The
prompt is separated from the default by the ´==>´ string. This
default separator string can be changed to anything you like with
the DEFAULTSEP option.
This feature is useful when you want to provide the user the most-
likely response to the prompt:
c UnixCP [UnixCopy] [DSELECTIONS] {PROMPT:Enter Destination==>/my/home/dir}
When the prompt is presented to the user, the default value is pre-
loaded into the response field. The user can either accept or edit
that string.
· {YESNO:Question-String==>Yes|No}
{YESNO:...} allows you to prompt the user with a dialog containing
a Yes/No question and buttons for their response. If the user
presses "Yes", command interpretation/execution continues. If the
user presses "No", the command is aborted. This is handy when you
want to make sure the user really wants to run the command before
continuing. For instance, suppose you define a recursive
file/directory deletion command. Before running it, it's good to
prompt the user to confirm their intentions:
D BigDelete {YESNO:Are You Absolutely Sure About This?} rm -rf [SELECTIONS]
You can also provide a default response to the question. It must
be either "Yes" or "No" (case-insensitive). Anything else will
produce an error. The prompt is separated from the default by the
´==>´ string. This default separator string can be changed to any‐
thing you like with the DEFAULTSEP option.
This feature is handy because you can pre-select the most likely
response to the dialog:
D BigDelete {YESNO:Are You Absolutely Sure About This?==>No} rm -rf [SELECTIONS]
Using Variable References Within Prompting Built-Ins
You may have guessed that there is something special about the Prompt‐
ing Built-In Variables. After all, they use a different delimiter pair
than all other variables in the twander configuration language. That's
because you can include references to other variables within a Prompt‐
ing Built-In like this:
PromptYN = Are You Sure You Want To Do This?
DefaultYN = No
a mycommand {YESNO:[PromptYN]==>[DefaultYN]} SomeDangerousCommand
A more sophisticated use of this would be when creating a "rename" com‐
mand. You often want to rename a file by changing only a few of its
characters, not the whole file name. Instead of forcing the user to
type the whole name in over again, why not just do this:
Prompt = New File Name?
r rename mv [SELECTION] {PROMPT:[Prompt]==>[SELECTION]}
Now when the user runs the command, the default string will be the name
of the file to be renamed. They can move around inside the dialog box
created by {PROMPT: ...} at runtime to edit the existing file name to
taste.
You can also use Execution Variables inside a prompting Built-In:
d setdate SomeDateCommand {PROMPT:Set Date To: ===>[`date`]}
Program Memory Built-Ins
As described previously, twander implements an advanced notion of a
Clipboard called "Program Memories". There is a corresponding group of
Built-In Variables which allows the contents of these memories to be
used in a Command Definition:
· [MEM1] ... [MEM12]
Return the file/directory names currently stored in the indicated
memory. For example, to move all the files/directories currently
named in the first Program Memory to the current directory we could
define a move command like this:
m move mv [MEM1] ./
Notes On Built-In Variable Use
· Built-In Variables which return a directory name do NOT append a
path separator character ("/" or "\") to the end of the name even
though it is visible in the GUI. This provides maximum flexibility
when defining commands. It is up to the command author to insert
the appropriate path separator character where needed. (NOTE: Ear‐
lier releases of twander did include the trailing path separator
and you may have to edit older Configuration Files accordingly.
This change was necessary because certain commands like Unix ´cp´
will not work if given a source directory with the path separator
included.)
For example, another way to express the full path of the currently
selected item is:
# Unix Path Separator
UPSEP = /
#Win32 Path Separator
WPSEP = \
[DIR][UPSEP][SELECTION]
- or -
[DIR][WPSEP][SELECTION]
Be aware that, because of twander quoting rules, such constructs
will result in strings like:
"/mydir"/"myfile"
- or -
"C:\mydir"\"myfile"
This should not generally be a problem with the various Unix
shells, and may work for some Windows commands. However, some Win‐
dows programs (noted in ´notepad´) reject this kind of filename
when passed on the command line. The workaround (and a generally
easier way to do this sort of thing), is to use the [DSELECTION]
built-in which returns the full path name of an item as a single
quoted string.
· All User-Defined, Environment, and Execution Variables are pro‐
cessed each time a command is run. This is especially important
for Execution Variables. The variable will be "executed" each time
the Command Definition in which it is referenced is run.
· Similarly, Built-In Variables are resolved on each command invoca‐
tion, i.e - at command runtime. The Built-Ins will always reflect
the current set of files selected in the user interface.
· The results of all built-ins (except HASH) are put inside double-
quotes when they are replaced in the Command String. This default
is recommended so that any built-in substitutions of, say, file‐
names with spaces in them, will be properly recognized by your com‐
mands. You can suppress the addition of double-quotes by using the
-t command line option when starting twander.
· Any of the variable types may appear multiple times in the same
Command String. For example, suppose you want to define a generic
Unix copy command:
g gencopy cp -R {PROMPT:Enter Source} {PROMPT:Enter Destination}
When the user presses "g" (or clicks on "gencopy" on the Command
Menu), they will be presented with two prompts, one after the
other, and then the command will run.
Associations
Most X-Windows desktops and Microsoft Windows support the idea of
"associations". That is, based on the name of a file, they "associate"
an application that can handle it. So, for example, a filename ending
in ".txt" is handled by a text editor, a filename ending in ".ps" is
handled by a PostScript processing program, and so on. This is handy
inside of visual interfaces because you can double-click on a file and
the interface can infer which program to load to process that file.
The problem is that the various X desktops and Microsoft Windows don't
all handle associations the same way. Some lighter X-Windows desktop
may not even have associations at all. In order for to remain portable
across operating systems, and work more-or-less the same way every‐
where, association support has been implemented directly within twander
itself.
All you have to do is tell twander which program to use for a given
file "type". A "type" is defined as a group of files whose names match
a so-called "wildcard" (more on that in a moment). You do this by
adding association statement to the Configuration File:
# Associations are in the form:
# ASSOC file-type-string command-to-handle-this-type-of-file
ASSOC *.txt emacs [SELECTION]
Thereafter, when twander runs, the "emacs" command will be loaded to
process any file whose name ends in ".txt" when the user selects that
file and either double-clicks on it or presses "Enter". On Windows
systems, this check is done in a case-insensitive way, so the associa‐
tion above would match files ending in, ".txt", ".TXT", ".Txt", and so
on. On Unix-like systems, the check is case-sensitive and the type
string must match exactly.
Notice that the "handler command" can consist of pretty much anything
that you can use in a command definition (as described in the previous
sections). For instance, you can do things like:
EDITOR = emacs -fn 10x20
ASSOC *.txt {YESNO:Are You Sure You Want To Edit This File?} [EDITOR] [SELECTION]
You can also insert special association command that will be used if no
other explicit association matches. Think of this as a "default" asso‐
ciation:
ASSOC *.pdf mypdfreader [SELECTION]
ASSOC *.ps mypostscriptprogram [SELECTION]
ASSOC * myfineeditor [SELECTION] # Default association
In this example, if you double-click or press "Enter" on any file not
ending in either ".pdf" or ".ps", the default association action will
be taken: The file will be opened with myfineeditor.
You can also define a list of file types to be excluded from associa‐
tion processing. This is handy if you want to use the default associa‐
tion feature for everything except a particular set of file types.
This feature is primarily useful on Windows systems where you want to
define your own default action, but want a few particular types of
files to use the underlying Windows associations.
To do this, put one or more statements in the following form in your
Configuration File:
ASSOC ! space-separated-list-of-file-types
For example:
ASSOC * myfineeditor [SELECTION]
ASSOC ! *.txt *.pyo *.ps
With this configuration, all files would, by default, be handled with
myfineeditor except files whose names end with .txt, .pyo, or .ps.
These excluded file types would be handed to the underlying OS for pro‐
cessing when they are selected.
Note that exclusion has higher precedence than any explicit associa‐
tion, not just the default association. If you do this:
ASSOC *.pdf mypdfreader [SELECTION]
ASSOC ! .pdf
You are effectively masking the explicit association for .pdf files.
You can also remove a previously defined association by leaving the
right-hand-side of the ASSOC statement blank:
# This example first defines, and then removes an association
# for .pdf files:
ASSOC *.pdf mypdfreader [SELECTION]
ASSOC *.pdf
# This one removes any exclusions you might have previously defined
ASSOC !
# This one removes any default association you might have previously defined
ASSOC *
This feature is primarily useful when you want to define associations
conditionally. That is, you can remove an association if a particular
conditional block is true. A typical use for this might be to get dif‐
ferent (or remove) associations based on what OS you're running. (See
the section below entitled: Conditional Processing Statements ).
Association Wildcards
Associations are built around the idea of a file "type". You want
files of the same type handled by the same application program. On
Windows systems, this has traditionally been the set of characters the
follow the period at the end of the filename. But this convention is
not consistently used on Unix-like systems. twander lets you use a
fairly powerful "wildcarding" system to define what is common about the
names of all files of a given type. Unix users will recognize this as
the shell globbing wildcards. Here they are implemented for both Win‐
dows and the Unix-like systems in the same way. The only difference is
that, on Windows, the check for a match ("is this file of type ...?")
is done without regard to case, whereas on the Unix-like systems, case
matters.
If you are unfamiliar with Unix-style shell globbing, many references
can easily be found on the web. Here is a summary of the "meta" char‐
acters supported:
* Matches everything - strings of any length with any characters
Example: *.text matches all filenames ending in ".text"
? Matches a single character
Example: foo.??? matches all filenames beginning with "foo."
and ending with any three characters.
[list] Matches any characters in the list
Example: foo*[tT] matches all filenames beginning with "foo",
with any number of characters following, and
ending with either the letters "t" or "T".
[!list] Matches any character NOT in the list
Example: foo*[!tT] matches all filenames beginning with "foo",
with any number of characters following, and NOT
ending with either the letters "t" or "T".
Lists can also be ranges. For example:
[a-z] Matches any lowercase letter
[A-Z] Matches any uppercase letter
[0-9] Matches any numeric digit
So, why bother with this? Because sometimes you want associate an
action with a set of files whose names are similar but vary in some
known way. For instance, suppose you have a database program that pro‐
duces files named "data01, data02, data03, ..." and so on. Instead of
having to write a separate association for each different possible
filename, you can just do this:
ASSOC data?? MyFineDatabaseProgram [SELECTION]
Forcing Association Case Insensitivity
Associations on Win32 are case insensitive because the underlying oper‐
ating system - while it preserves case - does not observe case distinc‐
tions in file and directories. On Unix-like systems, however, the
underlying operating system is case sensitive, so case matters when
defining associations for such systems.
There are circumstances where ignoring case in an association can be
helpful, even in Unix-like systems. For example, if you'd like to as‐
sociate an application with text files, it is annoying to have to write
individual associations for "*.txt", "*.Txt", "*.TXT", and so on.
Forcing case insensitivity allows us to write one association rule that
matches each of these file types:
ASSOC ! /*tXt # Exludes files ending in txt, TXT, TxT, TXt, ...
ASSOC /*txT emacs [SELECTION] # Invokes emacs for files ending as above
Prepending the "/" character to the association pattern is what tells
twander to ignore case when doing the matching.
Notice that exclusions have higher precedence than associations. In
the example above, files ending in txt, Txt, and so on would always be
excluded and the association with emacs would never happen.
To cancel a case insensitive association you must use the exact string
originally used to establish the association:
ASSOC /*txT emacs ....
ASSOC *txT # Does NOT undo the previous association
ASSOC *txt # Neither does this
ASSOC /*txT # But this does
A Few Association Subtleties
· The ASSOC keyword itself is case-sensitive - you must enter it
entirely in upper-case. However, the order of ASSOC statements is
unimportant. twander distinguishes ASSOC statements by their
unique file "type" strings. Well ... this is true so long as you
make sure the type strings are unique! Suppose you put this in
your Configuration File:
ASSOC *.text emacs [SELECTION]
ASSOC *xt ci [SELECTION]
A file whose name ends in ".text" will match both of these associa‐
tions. So which one does twander use? There is no way to tell -
it's a nonsense condition when a given file type matches more than
one association. The moral of the story here is to make sure each
of your ASSOC statements associates a completely unique file type.
Be really careful about this when using complex wildcards to spec‐
ify the file "type". It's easy for wildcards to overlap in their
definition of a filename and you'll end up with more than a sin‐
gle, unique association for a given type of file.
· The "default" association - if defined - will only be applied if no
explicit association for a given selection is found and the file in
question is not executable. That way, you can still double-click
(or press "Enter") on executable files to run them without the
default association getting in the way. Of course, if you've
explicitly defined an association for the type of executable file
selected, then that will be applied to the selected file. This can
be handy if, say, you don't want to actually run the executable,
but just edit it when you double-click on it.
· Be careful which Built In Variables you use in an association han‐
dler definition. Suppose you do this:
ASSOC *.txt emacs [SELECTIONS]
Note the use of the multiple selection Built In Variable, [SELEC‐
TIONS] (as opposed to the single selection [SELECTION] used in the
previous examples). What happens when you double-click or press
"Enter" when multiple files have been selected in the twander
interface? Well, it depends. The program decides which associa‐
tion to use based on the last filename you have selected. Suppose,
in order, you select "foo.c", "bar.py", and "baz.txt". Since the
last file selected ends with ".txt", the handler defined above will
match and all the files will be processed using this association.
This may not be what you want.
Even stranger things can happen if the last filename selected is an
executable and you've defined an association for it:
ASSOC *.py python [SELECTIONS]
Say you select "foo.c" and "bar.py". Since "bar.py" is the last
file in the multiple selection, it will match the association
above. This will effectively produce a command that like this:
python foo.c bar.py
Which is, um ... bogus.
As a general matter, multiple selection Built Ins are fine if you
are specifying an association handler that does things like edit‐
ing, viewing, printing, and so on. But be wary of them if the han‐
dler runs some language processor or other program that expects the
content of its arguments to be in a particular format.
Associations Differences Across Platforms
For the most part, twander associations work pretty much the same way
on all systems . There are, however, some slight differences between
the Unix-like systems and Windows.
· On Unix-like operating systems twander ignores the underlying asso‐
ciations (if any) of the system and/or X desktop. It only observes
its own associations. That's because there is no consistent asso‐
ciation mechanism across the many OS and desktop variants in use on
those platforms.
But Microsoft Windows is a different matter. All modern variants
of these systems have consistent built-in support for association.
twander was designed to "play nice" with the underlying associa‐
tions defined in the Windows registry. It works very simply: An
association defined in twander will take precedence over the native
Windows association. Say you define this:
ASSOC .txt myowneditor [SELECTION}
Then double-clicking "foo.txt" will cause "myowneditor" to be
invoked, even though Windows, by default, associates "notepad" with
text files.
If no matching twander association is found for a particular selec‐
tion, then the execution request is handed to Windows, and it's
association for that file type (if any) will be applied.
This is a very handy feature. You may wish to temporarily or per‐
manently change which program is associated with a given file type
when you're running twander. Instead of having to fiddle around
with reassociating things in Windows, you can just edit the twander
Configuration File.
· As noted in the previous section, matching the file "type" is case-
sensitive on Unix-like systems and case-insensitive under Windows.
This is because, although Windows observes case in file names, they
are not signficant. Similarly, file types listed in the associa‐
tion exclusion list are treated in a case-insensitive way on Win‐
dows systems.
· On Unix-like systems, if you attempt double-click or press Enter on
a file that cannot be executed, twander will display an error.
This happens anytime the file is non-executable and you've not
defined an association that matches it.
On Windows, twander does not do this. It simply passes the request
on to Windows. It does this in case there is a native Windows
association that applies for that file. If Windows cannot execute
the file, it will present an error message of its own.
Conditional Processing Statements
Most of twanders power lies in its ability to be customized to each
different user and operating system via its Configuration File. To
make this a bit easier to manage, the twander configuration language
recognizes so-called "Conditional Processing Statements". These state‐
ments give you the ability to write a single Configuration File which
automatically tailors itself to run twander properly wherever you are
running.
The general idea is to define a "Condition Block" which begins by doing
a logical test. If that test evaluates to True, all statements in the
block are included in the current configuration. If the test evaluates
to False, all statements to the end of the block are ignored.
A Conditional Block always begins with a "Condition Test Statement" and
ends with the ".endif" statement. Conditional Processing Statements
may be nested without limit. twander keeps track of which '.endif'
matches which Condition Test Statement. Like all Configuration File
entries, whitespace is ignored when processing Conditional Statements
and you are free to indent (or not) as you see fit.
Condition Test Statements are one of three types:
#####
# Existential: True if FOO or $FOO are defined
#####
.if [FOO]
...
.endif
.if [$FOO]
...
.endif
#####
# Equality: True if FOO or $FOO are literally
# the same as the test-string
#####
.if [FOO] == test-string
...
.endif
.if [$FOO] == test-string
...
.endif
#####
# Inequality: True if FOO or $FOO are literally
# not the same as the test-string
#####
.if [FOO] != test-string
...
.endif
.if [$FOO] != test-string
...
.endif
To make it easy to create conditional blocks based on the type of sys‐
tem you're running, twander automatically pre-defines two variables
which provide information about your system: .OS (typically: nt, posix)
and .PLATFORM (typically: freebsd4, linux-i386, win32). You should run
twander and examine the "User-Defined Variables" section of the Help
Menu to see how these variables are set on your system.
These predefined variables show up as "User Defined Variables" in the
various twander Help and Debug outputs, but they begin with a period to
remind you of their intended role. They will thus also sort first in
the User-Defined Variables section of the Help Menu.
Several things about Conditional Processing Statements are worth not‐
ing:
· Whitespace is mandatory after the ".if" statement - .if[FOO] is
syntactically incorrect. However, you need no whitespace on either
side of a "==" or "!=" test.
· All these tests involve either a User-Defined Variable or an Envi‐
ronment Variable, never a Program Option or Built In Variable.
· A Condition Test Statement always involves a variable reference
("[FOO]", never just "FOO") because we want the contents, not the
name, of the variable for the test.
· The Right Hand Side of an (in)equality test is just a string com‐
parsion - no variable expansion is done:
.if [FOO] == string[BAR]
This will not work as you might expect because the contents of
variable FOO are literally compared to the string, "string[BAR]".
Note too that this comparison is case-sensitive.
· The ".endif" statement must appear on the line by itself. Nothing
other than whitespace may precede it, and nothing (other than
whitespace or a comment) may follow it.
See the example ".twander" file provided in the distribution for some
extended examples of using conditionals in your Configuration File.
Also see the GOTCHAS section below for further discussion.
The Include Directive
You may include other files in your Configuration File with the follow‐
ing directive:
.include path-to-file
You may place as many of these statements in your Configuration File as
you wish. The only syntactic requirement is that there must be white‐
space between the directive and the file path. twander makes no
attempt to validate that path, and you will see an warning message if
the file you specify cannot be opened.
The most common reason to do this is to maintain a "standard" configu‐
ration in a separate file which is controlled by the system administra‐
tor. This is especially handy on larger systems with multiple users.
The system administrator provides a read-only copy of the standard con‐
figuration in a place anyone can read it. Everyone is free to use (but
not modify) that standard configuration. You are then free to add to,
or even override the standard configuration content with statements of
your own following the ".include". Suppose you have the following
"standard" Configuration File available on your system:
# Contents of /usr/local/etc/.twander.global
SHELL = bash -c
XTERM = xterm -fn 9x15 -l
VSHELL = [XTERM] -e [SHELL]
DIRSC1 = /usr/local
DIRSC2 = /usr/sbin
t terminal [XTERM]
Now, you can create your own personal Configuration File which takes
advantage of this standard file, but augments it with additional con‐
figuration information of your choosing:
# Contents of $HOME/.twander
.include /usr/local/etc/.twander.global
DIRSC2 = /etc
l ls [VSHELL] 'ls -al | [$PAGER]'
Keep in mind that twander reads the contents of its Configuration File
in order. In this case, it means that all of "/usr/local/etc/.twan‐
der.global" is read and then the rest of "$HOME/.twander" is read. If
something is defined more than once, the last definition is what is
used. In this case, DIRSC2 is overriden in the local Configuration
File and is ultimately assigned to "/etc". Similarly, you can override
previous definitions for User-Defined Variables and even Command Defi‐
nitions.
The program checks to see if you attempt to do a "circular" include.
For example, say file "A" .includes file "B" and file "B" then
.includes file "A". This wold create a neverending "circle" of
included files. If twander detects this, it will display an error
describing the problem and skip the offending line.
ADVANCED WINDOWS FEATURES
As shipped from the factory, twander runs pretty much identically on
various Unix variants (FreeBSD, Linux) and Windows. However, twander
is written to take advantage of Mark Hammond's ´win32all´ Python exten‐
sions if they are present on the system. These extensions add many
Windows-specific features to Python and allow twander to provide quite
a bit more Windows-centric information about files, directories, and
drives. You do not have to install ´win32all´ for twander to operate
properly on your Windows system. Installing this package just means
you'll get even more twander features on Windows than you would other‐
wise. If you've installed ´win32all´, you can toggle these features
on- and off with the TOGWIN32ALL key described above.
Getting ´win32all´
You can get the ´win32all´ extensions one of two ways. If you've
installed the Active State version of Python for Windows,
(http://www.activestate.com/Products/ActivePython/) ´win32all´ is
already installed on your system. If you installed the standard Python
release for Windows (http://www.python.org/download/download_win‐
dows.html), you must add ´win32all´ to your installation. You'll find
the extensions and painless installation instructions at: http://star‐
ship.python.net/crew/mhammond/
New Features Supported With ´win32all´
One important note is in order here: The features enabled by ´win32all´
are only available on "true" Windows systems like Windows 2000 and Win‐
dows XP. Earlier versions of Windows like Win98 and WinME emulate por‐
tions of the Win32 API and do not implement the advanced security fea‐
tures found in the NTFS file system. Therefore, as noted below, some
of these features will not work on any of the older 16-bit Windows
operating systems. twander handles this gracefully without blowing-up
so you can safely have ´win32all´ installed on one of these older sys‐
tems to take advantage of the features that do work.
Once you have these extensions installed, twander will automatically
enable three new features otherwise unavailable.
· When viewing file/directory detail information, the owner and group
names will be the actual names reported by the operating system
rather than the filler values normally seen in those fields
(´win32owner´ and ´win32group´). (Does not work on older Windows
systems like Win98.)
· Instead of showing Unix-style file permissions (which don't mean
much under Windows), systems with ´win32all´ installed will show
the so-called "file attributes" maintained by the operating system.
Each detailed entry in the display will have one or more of the
following attributes displayed in what is normally the Unix permis‐
sions field:
d - Directory
A - Archive
C - Compressed
H - Hidden
N - Normal
R - Read-Only
S - System
· A top-level "Drive List View" is enabled if ´win32all´ is
installed. This shows you a list of all currently available drives
reachable by the system, and information about those drives. For
locally attached drives, the drive label is shown. For network-
attached drives, the share string is shown. The drive type
(CD/DVD, Fixed, Ramdisk, Remote, Removable) is shown as are the
free, and total space statistics. As is the case with other twan‐
der displays, these details can be toggled on- and off via the
TOGDETAIL key.
You can enter the Drive List View in a number of ways:
1) Select the ".." from the root directory of any drive.
2) Enter the string "\\" from the CHANGDIR dialog.
3) Press the DRIVELIST key. (default: Control-k)
4) Start twander using "\\" as the starting directory
argument, either on the command line or using the
Configuration File STARTDIR option.
The "Drive List View" is available on all Windows variants, however
the free/total space values will be incorrect on older systems like
Win98.
Notes On Drive List View
The Drive List View is a little different than the usual file/directory
view. Program behavior (semantics) is thus also slightly different
than usual in several ways:
· While in Drive List View, the various Built-In Variables which
return the current selections will return the name or names of the
selected drive(s) (without a trailing slash) just as you would
expect them to in a normal file/directory view. This allows you to
write commands which take drive names (letters) as an argument.
The [DIR] Built-In returns an empty string in this view.
· Normally, as you navigate around a file system, twander sets its
own program context to the current directory. This is why you can
write Command Definitions using only the file/directory name cur‐
rently selected - twander knows the current directory. When you
are in Drive List View, the notion of "current directory" has no
real meaning. So, twander treats the directory from which you
entered Drive List View as the "current directory" while in that
view.
· By default, twander automatically rereads the current view about
every 3 seconds. This is fine for a file/directory view but would
be annoyingly slow in the Drive List View since it takes a moment
or two to get the status of any floppy disk drives attached to the
system. Instead of forcing the user to listen to (and wait for)
the floppy drive status to be determined every 3 seconds, twander
only reads the drive information once when it enters Drive List
View. This means if a drive is connected or a floppy is inserted
into the system while in Drive List View, this fact will not be
automatically noted. You can force a manual update of the Drive
List View by pressing the REFRESH key. (default: Control-l)
· The TOGWIN32ALL key (default: Control-w) is disabled in Drive List
View. Drive List View is only available in ´win32all´ mode and
toggling that mode off makes no sense here.
· The SELALL (default: Control-comma) and SELINV (default: Control-i)
features work slightly differently in Drive List View than they do
otherwise. Ordinarily, these features never select the first item
of a file/directory display because it is always the ".." entry
pointing to the directory parent. In Drive List View, the first
entry is an entry of interest - usually, but not always, Drive A: -
so these two keys do select it as is appropriate.
Disabling ´win32all´ Features
You can toggle these features on-and off using the TOGWIN32ALL key.
(default: Control-w) You can also permanently disable them by setting
the USEWIN32ALL option to False in the Configuration File. This allows
you to leave ´win32all´ installed on your system if you need it for
other reasons but don't want these features enabled in twanderGOTCHAS
There are several tricky corners of twander which need further explana‐
tion:
Program Starts Very Slowly
twander attempts to determine the name of the host on which it is run‐
ning at program startup. This is used in the title bar display. It
first looks to see if the environment variable HOSTNAME is set, and
uses that value if it is. If this variable is not set, twander does a
socket call to see if it can determine the hostname that way.
Either of these methods works fine, but the socket call can be very
slow if the network is misconfigured or malfunctioning. If twander is
starting very slowly, try setting HOSTNAME explicitly in your environ‐
ment - this will prevent the socket call from ever taking place. A
simple way to do this with ´ksh´ or ´bash´ is:
export HOSTNAME=`hostname`
(Note the backticks used to execute the ´hostname´ program and assign
its results to HOSTNAME.)
Be aware that ´bash´ claims to automatically set this variable when it
starts. However, it does not appear to export it properly on some sys‐
tems (noted on FreeBSD 4.7 with ´bash´ 2.05b). In this case, you have
to do this manually as just described even when using ´bash´
On Windows, environment variables are set via the System Properties
menu.
Program Loads Slowly
twander is a fairly large Python program and can take a few seconds to
load and initialize, especially on older, slower systems. You can
speed this up a bit by creating an optimized byte-code version of the
program as follows (make sure you have appropriate administrative per‐
mission to do this):
1) Go to the directory where the twander.py file is located.
2) Type the following command: python -O
3) Once Python is loaded type: import twander
4) Exit twander.
5) Exit Python by pressing Control-d on Unix or
Control-z on Windows.
6) You will now see a new file in this directory: twander.pyo
This file should be significantly smaller than twander.py.
7) Now you can run the program by entering: python twander.pyo
on Unix/Windows or pythonw twander.pyo on Windows.
8) You have to repeat this procedure each time you install
a new version of twander.py
Cannot Enter Certain Directories On Windows
Windows allows file/directory names to contain non-ASCII characters.
Python, as shipped, defaults to ASCII only and grumbles mightily when
it is asked to deal with a string containing characters with ordinal
values greater than 127 (i.e., 8-Bit "extended" ASCII). The solution
to this problem is to enable Python to handle non-ASCII strings. This
is done by editing a file called "site.py". This file is normally
found in:
C:\Program Files\PythonXX\Lib
Where "XX" is the actual version of Python you're running.
Open this file with an editor and look for the following text:
encoding = "ascii" # Default value set by _PyUnicode_Init()
if 0:
# Enable to support locale aware default string encodings.
import locale
Change the if 0: statement to if 1: and the problem will disappear.
Getting Command Results Displayed In A New Window
When you invoke a command via twander (whether via a command definition
in the Configuration File or the keyboard shortcut), you generally want
it to run in a new window. This turns out to be tricky on Unix-like
systems. If the program you are running is GUI-aware, this should not
be a problem. However, if you are using twander to run a command line
program or script, you have to take extra care in the formulation of
the Command String. In the case of Unix-like systems you have to
invoke the command so that it runs in some GUI context. Say you want
to use a pager like ´less´ to view files. You would expect that this
entry might do it:
V view less [DSELECTIONS]
Sadly, this will not work, at least not the way you expect. If you
started twander from a terminal session and use the command above, it
will work, but the results will appear in the invoking terminal window,
not in a new window as you might expect. If you started twander from a
GUI or disconnected it from the initiating terminal with a ´nohup´ ...
& invocation, you will get no output. This is not a twander problem,
it is innate to how command line programs run under Unix shell control.
To achieve the desired results, you have to create a new GUI window in
which your command can run and display results. The easiest way to do
this is to run your command in a new ´xterm´ window like this:
V view xterm -l -e less [DSELECTIONS]
Some program further require you to provide a shell so they can execute
correctly. For instance, running ´ls´ in a command definition requires
something like this:
L lshome xterm -l -e bash -c 'ls / | [$PAGER]'
In fact, this idiom is so common, you will see variables defined in the
example ".twander" file to simplify such definitions (comments
removed):
SHELL = bash -c
VSHELL = [XTERM] [SHELL]
XTERM = xterm -fn 9x15 -l -e
Now you can write the command above like this:
L lshome [VSHELL] 'ls / | [$PAGER]'
This causes your command line program to execute in an ´xterm´ context
and under a shell interpreter.
This is not as much an issue on Windows systems where the first form of
the command above works fine. Windows appears to have no problem
invoking a new window whether the command is GUI-aware or not.
However, which terminal window is used for output can be confusing. If
you start twander from a terminal session, all terminal output will be
sent to the terminal session you used to invoke the program. The way
to work around this is to start twander from a Windows shortcut, using
´pythonw.exe´ rather than ´python.exe´. Now each time you run a com‐
mand that needs a terminal session for output, Windows will automati‐
cally create that session for you.
Using Shell Wildcards In Command Definitions
The {PROMPT:...} Built-In Variable is provided to make it possible to
write general-purpose commands which interact with the user. For exam‐
ple, you might want to define a directory listing command for Windows
like this:
L DirList dir {PROMPT:Directory Of What?} | more
When the user presses the "L", they are presented with a dialog box
into which they enter their directory name or wildcard pattern such as
"\*.bat" and everything works as expected.
On Unix-like systems, however, this does not work as expected. Suppose
we define the command for these systems to be:
L DirList [VSHELL] 'ls -l {PROMPT:Directory Of What?} | [$PAGER]'
This works fine so long as the user does not enter a wildcard pattern
in response to the prompt. Why? Recall that twander quotes all Built-
In Variable substitutions by default. If the user enters this at the
prompt:
/kern*
The command twander tries to execute is:
VSHELL Stuff ... 'ls -l "/kern*" | ... pager stuff
The argument to ´ls´ is double-quoted. The Unix shells understands
this kind of quoting to mean no expansion of wildcard characters is to
be done, which is the exact opposite of what we want.
You might think that the easy way to solve this problem is to turn off
argument quoting with the -t command line flag. However, this is not
really practical. Quoting is on or off globally in the program. Turn‐
ing it off means no Built-In Variable substitutions will be quoted.
That's fine so long as no directory/file you select via the user inter‐
face has a space in the name. However, you are almost certain to run
into such files sooner or later. (Recall that the only way to deal a
directory/filename with spaces in it as a single argument is to quote
that name.)
So, we need a way to leave quoting on but also properly deal with wild‐
card string entries from the user. Fortunately, because of the rich‐
ness of Unix shells, there is a simple way to do this: we'll use a
"shell variable" to hold the user's response and the shell's ability to
handle multiple commands on one line separated by semi-colons:
# Note that the line below is split for printing purposes
# In an actual Configuration File, this needs to all be on one line
L DirList [VSHELL] 'UsrResp={PROMPT:Directory Of What?} ;
ls -l $UsrResp | [$PAGER]'
Why does this work? Because the shell interprets (and drops) the dou‐
ble-quotes, when the results of the {PROMPT:...} are assigned to Usr‐
Resp . The later reference to "$UsrResp" returns just the string the
user entered without the quotes and the command works as expected.
Interestingly, this problem does not occur when entering text via the
RUNCMD dialog. (default: Control-z) Here the text you enter is not
part of a Built-In Variable substitution, so it is not quoted. (The
exception, of course, would be if you entered a {PROMPT:...} reference
in the RUNCMD dialog. In this case, the same problem we've just
described could occur.)
Modal Operation Of New Windows
Notice our example commands above do not end with "&". These should
not be needed on either Unix-like or Windows operating systems. When a
command is executed, twander starts a process which runs concurrently
with twander itself. This means you should be able to continue using
twander while the new command executes.
If you enable the use of threads by setting USETHREADS to True, you may
see twander locked out while the new command runs - so-called "modal"
operation. If this happens, it means your system does not completely
or correctly implement threading and you must use conventional "heavy
weight" processes (the default) rather than threads.
Windows Don't Disappear On Command Completion
It appears that some X Windows implementations (noted on XFree86 /
FreeBSD) do not correctly destroy an ´xterm´ window after a command
initiated with -e terminates. This is not a twander problem - it is an
artifact of thread behavior on such systems and only happens if you set
USETHREADS=True. The workaround is to use the default
USETHREADS=False setting.
Program Behavior Incorrect When A Window Is Resized
Certain Unix programs such as ´less´ appear to not work correctly when
the window in which they are running is resized. The program seems to
not be properly informed that the window size has changed. This seems
to be an interaction caused by running such programs as threads rather
than processes. Once again, the workaround here is to not change the
USETHREADS=False default setting.
Really Slow Response Times When Changing To A New Directory
You may occasionally see really slow response times when you change to
a new directory. This occurs when you enter a huge directory with
thousands of file or subdirectory entries. twander has to to compute
the detail information for each of these entries and this can take a
lot of time. On a fast machine with modern hard drives and con‐
trollers, twander is able to process several thousand entries in just a
second or two. However, a number of factors can significantly slow
down this process:
· The Autorefresh interval is set too low. Processing the directory
takes so long that as soon as one refresh finishes, the next starts
right away. The program will appear to hang. There are two possi‐
bilities here. Either disable autorefreshing (via the -r command
line option or the AUTOREFRESH Configuration File option), or set
the REFRESHINT value to some high number so that twander has plenty
of time to process a directory before the next refresh occurs.
· Slow disk drives. You can really watch twander grind if you change
to a large directory on a CDROM, for instance. There is no good
solution here. These drives are inherently slower than hard
drives, and you just have to wait. Make sure you lengthen your
refresh interval as described in the previous bullet.
· By far the worst culprit here, though, is when running Windows with
´win32all´ options enabled. It takes a lot more work to get
win32all-style information about each directory entry, than the
default Unix-style information. Simply turning off ´win32all´
features alone can speed up directory processing by a factor as
high as 4X.
When you combine these factors, it is possible to get really long pro‐
cessing times. One test situation we observed was reading a directory
with over 4000 entries on a Windows CDROM. With ´win32all´ processing
enabled this took over a minute. By disabling these features, the time
came down to under 30 seconds.
· For all these reasons, twander implements an "adaptive refresh"
scheme by default. Whenever a directory is read, the time to do so
is tracked. If that time is less than the current value of
REFRESHINT - i.e., The directory read took less than REFRESHINT
milliseconds to complete - nothing special happens. But, if the
actual directory read time takes longer than REFRESHINT millisec‐
onds, twander adjusts the value of REFRESHINT upwards. That way,
you're guaranteed to have time after the read completes to actually
do something.
This dynamic adjustment takes place on every directory read. If you go
to a slow directory and REFRESHINT gets dynamically adjusted to, say,
25 seconds, when you go back to a faster/smaller directory, REFRESHINT
will be reset to its default value. The changing value of REFRESHINT
is not shown in the program options help menu. The value there is the
one set by default or set in the Configuration File. Think of this as
the "base" value for REFRESHINT.
If you don't like this adaptive refresh interval business, set the
ADAPTREFRESH program option to False. In that case, REFRESHINT will be
strictly observed.
Your Configuration File Does Not Produce The Desired Results
It's easy to fall into the trap of treating the twander configuration
capabilities as a real "programming language". It is not, it is a
fairly simple macro language that does very little more than string
substitutions. Keep the following rules in mind as you edit your con‐
figuration:
· Except for conditional tests, Environment Variables and User-
Defined Variables are never resolved until they appear in a Command
Definition.
· The Right Hand Side of Option Statements, Key Binding Statements,
Directory Shortcut Statements, Wildcard Statements, and Condition
Test Statements are treated literally - No variable substitution is
ever done there.
· A Condition Test Statement always involves a variable reference,
never just a variable name.
· For a Condition Test Statement to be true, the referenced variable
must be defined and any equality test must be satisfied.
· When testing for the existence of a User-Defined or Environment
Variable, twander does not care what value the variable contains.
It is perfectly permissible to have either type of variable set to
an empty string. The fact that the variable exists at all is what
makes the following construct true:
CondVar =
.if [CondVar]
....
.endif
· You have to be careful when overriding variable or command defini‐
tions. User-Defined Variables referenced in a Command Definition
are de-referenced at the time the Command Definition is encountered
in the Configuration File. This means that if you change a User-
Defined Variable after it has already been used in a Command Defi‐
nition, only future references to that variable will reflect the
change:
FOO = bar
x cmd1 command [FOO]
FOO = baz
y cmd2 command [FOO]
In this example, the first command will be defined as "command
bar", but the second will be defined as "command baz".
Watch for this, especially, when using the ".include" directive
and then overriding a variable defined in that file.
Common mistakes include:
#####
# Trying to embed a variable where it will never be resolved
#####
DIRSC03 = [$SystemDrive]\Program Files
MYCOLOR = blue
FCOLOR = [MYCOLOR]
#####
# Expecting a conditional variable to be resolved before the test
# Suppose $EDITOR is set to "/usr/local/bin/emacs" ...
#
# The following will be False because [EDT] equals
# the string "[$EDITOR]". It is not replaced
# with "/usr/local/bin/emacs" until [EDT] appears
# in a Command Definition
#####
EDT = [$EDITOR]
.if [EDT] == /usr/local/bin/emacs
...
.endif
# Note, however, that *this* would work because
# Environment Variables are permitted in conditionals ...
.if [$EDITOR] == /usr/local/bin/emacs
...
.endif
#####
# A badly formed condition is ignored (after a warning)
# which means *all the lines following will be processed*
# (until a valid condition statement which is False is
# encountered).
#####
PROCESS = no
SUBPART = no
# We meant not to process the following but all the
# lines up to the next .if statement *are* processed
# because the bad syntax on the next line means it's ignored
.if PROCESS != no
... # Processed!
.if [SUBPART] == yes # *Now* we'll stop
...
.endif
.endif
OTHER
File/Directory name sorting is done without-case sensitivity on Windows
systems because the underlying operating system does not observe case.
Because this program has not been tested on anything other than Unix-
like and Windows systems, command execution by double-click or pressing
Enter is inhibited on all other operating systems by default.
You must have Python 2.2 or later installed as well as Tkinter support
installed for that release. In the case of Windows, Tkinter is bundled
with the standard Windows Python distribution. In the case of Unix-
like systems, you may have to first install Python and then the appro‐
priate release of Tkinter. This is the case, for example, with Free‐
BSD.
You must install the ´win32all´ extensions if you want to use the
advanced Windows features.
You'll find the latest version and, occasionally, Release Candidates of
the next version of twander at:
http://www.tundraware.com/Software/twander
You should check this site regularly for updates and bug-fixes. The
´WHATSNEW.txt´ file describes changes since the last public release of
the program.
BUGS AND MISFEATURES
As of this release, a number of problems relating to twander use have
been noted:
· The Configuration File parser does no validation to check the san‐
ity of its various entries for Program Options, Key Bindings,
Directory Shortcuts, Variable Definitions, and Command Definitions.
It is entirely possible to edit something into this file that makes
no sense at all and causes twander to misbehave.
· There appears to be a Tkinter/Tk bug on Unix which sometimes
inhibits the correct title display when you tear-off a menu. This
is a cosmetic defect and may disappear in future releases of Tkin‐
ter/Tk/X-Windows.
· Some ´win32all´ features do not work correctly or at all on older
Windows OSs. For example, the free/total space available in the
Drive List View has been noted to display incorrect values on
Win98. Similarly, the owner and group names are displayed as
"Unavailable" on pre-NTFS file systems. These are OS limitations
which twander handles gracefully.
· If you are using ´bash´ as your Unix shell, be aware that, although
it sets HOSTNAME automatically, this environment variable appears
to not be exported consistently on all systems.
· If you are running Windows and have file or directory names with
non-ASCII characters in them, you must configure Python to properly
deal with such characters. This is described above in the section
entitled, GOTCHAS.
· This program has not been tested on MacOS. It has been reported
that Python on MacOS X returns ´posix´ as its OS name. If true,
twander should work as written, though we've not verified this.
Please let us know how/if it works there and any issues you dis‐
cover.
INSTALLING twander
Installation of twander is fairly simple and takes only a few moments.
The most important thing before installing the program is to make sure
you have Python 2.2 (or later) with Tkinter support installed on your
system.
One other note: However you install the program, it is probably easiest
to get started by editing the example ".twander" file to taste. Be
aware that this file is shipped with everything commented out. You
have to uncomment/edit the section relevant to your operating system:
Unix-like or Windows.
Installing Using The FreeBSD Port
If you've installed twander using the FreeBSD port, all you have to do
is copy the example Configuration File, ".twander" found in
/usr/local/share/doc/twander to your home directory and edit it to
taste. (You'll also find documentation for twander in various formats
in this directory as well.)
Make sure that /usr/local/bin is in your path. To start the program,
just type "twander.py" from the shell prompt.
Installing Manually On A Unix-like System
Copy the "twander.py" file to a directory somewhere on your path.
(/usr/local/bin is a good candidate). Make sure this file has permis‐
sions 755 and owner/group appropriate for your system (root/wheel,
root/root, or bin/bin). Copy the ".twander" file to your home direc‐
tory and edit to taste.
To run the program, just type "twander.py" from a shell prompt.
Red Hat Linux Users Please Note: RH Linux (and possibly other Linux
systems) installs two versions of Python. Version 1.52 is called
´python´, and Version 2.2 is called ´python2´. twander requires the
latter and will not run on the former. As shipped, twander invokes
Python with the Unix shell "#!" mechanism using the name ´python´ -
which in this case is the wrong version. You can work around this
problem one of several ways:
· Rename ´python´ to ´python1´ and then rename ´python2´ to ´python´.
(Not Recommended - could break other programs.)
· Write an alias or shell script which explicity starts twander with
the correct version of Python:
#!/bin/sh
python2 twander.py $*
· Change the first line of the twander code to refer to ´python2´
instead of ´python´.
Red Hat users who have upgraded from earlier Linux versions should also
note that you may have files in your home directories owned by owners
and groups which are no longer defined in the system! twander shows
the owner and group fields for such files as numbers rather than names.
As best as we can determine, this is caused when an RH installation is
updated from an older version.
Installing Manually On A Windows System
Copy the "twander.py" file to a directory somewhere on your path, or
create a new directory to hold this file and add that directory path to
the PATH environment variable.
IMPORTANT NOTE TO WINDOWS USERS: Windows has the old MS-DOS legacy of
assuming that a "." begins a file "extension". Although you can create
and read files in the form ".something", it is not recommended because
many Windows programs get confused when they see this. It is also dif‐
ficult to remove files named this way with the standard Windows pro‐
grams and utilities. This is especially the case for older Windows
operating systems like Win98. For this reason, it is recommended that
you rename the ".twander" default Configuration File provided in the
program distribution to something else like "twander.conf" and use the
twander-c command line option to point to this Configuration File.
On Windows, where to put the Configuration File raises an interesting
question. Microsoft operating systems normally do not set the "HOME"
environment variable, because they have no notion of a "home" directory
- Well, they do, but it is called "USERPROFILE" not "HOME". So, you
can either create a new user-specific environment variable called HOME
yourself (which points to your desired home directory) or you can
invoke twander with the -c argument to explictly declare where it can
find its Configuration File.
You can run the program several ways on Windows systems:
· Create a Windows shortcut which points to the "twander.py" file
using the "pythonw" command to invoke it. Normally, starting a
Python program from the Windows GUI creates a parent window which
persists as long as the program runs. Using "pythonw" instead of
"python" to run your program suppresses the creation of this blank
parent window. For example, you might have something like this in
the "Target:" field of your shortcut:
"C:\Program Files\Python22\pythonw.exe" C:\twander.py \
This runs the program starting at the root directory of the current
drive (assuming "twander.py" is located in C:\.
· Start a command line window and issue a command like the one above
directly from the command line.
· Use Windows Explorer (or better still, an already running instance
of twander!) to navigate to the directory where "twander.py" is
located. Double-click on the file. If Python is properly
installed, there should be an association for ".py" file types and
twander should start automatically.
GETTING HELP: THE twander MAILING LIST
TundraWare Inc. maintains an email list for twander users to get help
and exchange ideas. To subscribe, send mail to:
majordomo@tundraware.com
In the body (not the subject line) of the email, enter the following
text, substituting your own email address as indicated:
subscribe twander-users your-email-address
DESIGN PHILOSOPHY
Graphical User Interfaces (GUIs) are a blessing and a curse. On the one
hand, they make it easy to learn and use a computer system. On the
other, they are a real inconvenience to experienced users who are touch
typists. Taking hands off the keyboard to use the mouse can really
slow down a good typist.
Nowhere is this more apparent than in filesystem browsers. In one cor‐
ner we have the GUI variants like ´Konqueror´ and ´Microsoft Windows
Explorer´. These are very easy to use but you pretty much need the
mouse in your hand to do anything useful. In the other corner are the
text-based file browsers like ´List´, ´Norton Commander´, and ´Midnight
Commander´. These are really efficient to use, but have limited func‐
tionality and generally do not operate very well on groups of things.
Both of these approaches also suffer from the well-known interface
problem of "What You See Is All You Get" - Each program has a prede‐
fined set of commands and the user cannot easily extend these with
their own, new commands.
twander is another approach to the filesystem navigation problem which
embraces the best of both the GUI-based approach and the text-based
approach. It also provides a rich mechanism whereby each user can eas‐
ily define their own command set and thereby customize the program as
they see fit. This is done with a number of key features:
1) The Navigation of the filesystem is graphical - you can use the
mouse to select files, directories, or to change directories.
However, each major filesystem navigational feature is also dou‐
bled on the keyboard (using Control keys) so you can move around
and select things without ever touching the mouse.
2) twander also supports a number of navigation shortcuts. It pro‐
vides single control-key access to changing directories, moving
to the previous directory, moving up one directory level, moving
to any previously visited directory, (de)selecting any or all
files/directories in the current view, and escaping to the oper‐
ating system to run a command. Some (but not all) of these fea‐
tures are also doubled via GUI/mouse operations.
3) There are no built-in file or directory commands. All commands
which manipulate the files or directories selected during navi‐
gation are user-defined. This Command Definition is done in an
external Configuration File using a simple but powerful command
macro language. This means that that the command set of the
program can easily be changed or expanded without having to
release a new version of twander every time. Better still,
every different user can have their own command set defined in a
way that suits their style of working. Best of all, commands
can be invoked either graphically (with a mouse click) or via a
single keypress to minimize moving your hands off the keyboard.
4) Because twander is written in Python using Tkinter, the same
program runs essentially identically on many Unix-like and Win‐
dows systems. The only thing that may need to be changed across
these various platforms are the Command Definitions in the con‐
figuration file. You only need to learn one interface (and the
commands you've defined) across all the different systems you
use.
The consequence of all this is that twander is an extremely powerful
and highly customizable filesystem navigator. Once learned, both navi‐
gation and command execution are lightning-fast (or at least, as fast
as your machine can go ;) while minimizing dependency on the mouse.
COPYRIGHT AND LICENSINGtwander is Copyright(c) 2002-2009 TundraWare Inc. For terms of use,
see the twander-license.txt file in the program distribution. If you
install twander on a FreeBSD system using the 'ports' mechanism, you
will also find this file in /usr/local/share/doc/twander.
AUTHOR
Tim Daneliuk
twander@tundraware.com
DOCUMENT REVISION INFORMATION
$Id: twander.1,v 1.155 2009/07/01 20:16:33 tundra Exp $
TundraWare Inc. twander(1)
