tclsh(1) Tcl tclsh(1)
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NAME
tclsh - Simple shell containing Tcl interpreter
SYNOPSIS
tclsh ?fileName arg arg ...?
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DESCRIPTION
Tclsh is a shell-like application that reads Tcl commands
from its standard input or from a file and evaluates them.
If invoked with no arguments then it runs interactively,
reading Tcl commands from standard input and printing
command results and error messages to standard output. It
runs until the exit command is invoked or until it reaches
end-of-file on its standard input. If there exists a file
.tclshrc in the home directory of the user, tclsh evaluates
the file as a Tcl script just before reading the first
command from standard input.
SCRIPT FILES
If tclsh is invoked with arguments then the first argument
is the name of a script file and any additional arguments
are made available to the script as variables (see below).
Instead of reading commands from standard input tclsh will
read Tcl commands from the named file; tclsh will exit when
it reaches the end of the file. There is no automatic
evaluation of .tclshrc in this case, but the script file can
always source it if desired.
If you create a Tcl script in a file whose first line is
#!/usr/local/bin/tclsh
then you can invoke the script file directly from your shell
if you mark the file as executable. This assumes that tclsh
has been installed in the default location in
/usr/local/bin; if it's installed somewhere else then
you'll have to modify the above line to match. Many UNIX
systems do not allow the #! line to exceed about 30
characters in length, so be sure that the tclsh executable
can be accessed with a short file name.
An even better approach is to start your script files with
the following three lines:
#!/bin/sh
# the next line restarts using tclsh \
exec tclsh "$0" "$@"
This approach has three advantages over the approach in the
previous paragraph. First, the location of the tclsh binary
doesn't have to be hard-wired into the script: it can be
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tclsh(1) Tcl tclsh(1)
anywhere in your shell search path. Second, it gets around
the 30-character file name limit in the previous approach.
Third, this approach will work even if tclsh is itself a
shell script (this is done on some systems in order to
handle multiple architectures or operating systems: the
tclsh script selects one of several binaries to run). The
three lines cause both sh and tclsh to process the script,
but the exec is only executed by sh. sh processes the
script first; it treats the second line as a comment and
executes the third line. The exec statement cause the shell
to stop processing and instead to start up tclsh to
reprocess the entire script. When tclsh starts up, it
treats all three lines as comments, since the backslash at
the end of the second line causes the third line to be
treated as part of the comment on the second line.
VARIABLES
Tclsh sets the following Tcl variables:
argc Contains a count of the number of arg
arguments (0 if none), not including the name
of the script file.
argv Contains a Tcl list whose elements are the
arg arguments, in order, or an empty string
if there are no arg arguments.
argv0 Contains fileName if it was specified.
Otherwise, contains the name by which tclsh
was invoked.
tcl_interactive
Contains 1 if tclsh is running interactively
(no fileName was specified and standard input
is a terminal-like device), 0 otherwise.
PROMPTS
When tclsh is invoked interactively it normally prompts for
each command with ``% ''. You can change the prompt by
setting the variables tcl_prompt1 and tcl_prompt2. If
variable tcl_prompt1 exists then it must consist of a Tcl
script to output a prompt; instead of outputting a prompt
tclsh will evaluate the script in tcl_prompt1. The variable
tcl_prompt2 is used in a similar way when a newline is typed
but the current command isn't yet complete; if tcl_prompt2
isn't set then no prompt is output for incomplete commands.
KEYWORDS
argument, interpreter, prompt, script file, shell
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