PERLOS2(1) Perl Programmers Reference Guide PERLOS2(1)NAMEperlos2 - Perl under OS/2, DOS, Win0.3*, Win0.95 and
WinNT.
SYNOPSIS
One can read this document in the following formats:
man perlos2
view perl perlos2
explorer perlos2.html
info perlos2
to list some (not all may be available simultaneously), or
it may be read as is: either as README.os2, or pod/per_
los2.pod.
To read the .INF version of documentation (very recom
mended) outside of OS/2, one needs an IBM's reader (may be
available on IBM ftp sites (?) (URL anyone?)) or shipped
with PC DOS 7.0 and IBM's Visual Age C++ 3.5.
A copy of a Win* viewer is contained in the "Just add OS/2
Warp" package
ftp://ftp.software.ibm.com/ps/products/os2/tools/jaow/jaow.zip
in ?:\JUST_ADD\view.exe. This gives one an access to EMX's
.INF docs as well (text form is available in /emx/doc in
EMX's distribution).
Note that if you have lynx.exe installed, you can follow
WWW links from this document in .INF format. If you have
EMX docs installed correctly, you can follow library links
(you need to have "view emxbook" working by setting "EMX
BOOK" environment variable as it is described in EMX
docs).
DESCRIPTION
Target
The target is to make OS/2 the best supported platform for
using/building/developing Perl and Perl applications, as
well as make Perl the best language to use under OS/2. The
secondary target is to try to make this work under DOS and
Win* as well (but not too hard).
The current state is quite close to this target. Known
limitations:
Some *nix programs use fork() a lot; with the mostly
useful flavors of perl for OS/2 (there are several
built simultaneously) this is supported; some flavors
do not. Using fork() after useing dynamically load
ing extensions would not work with very old versions
of EMX.
You need a separate perl executable perl__.exe (see
the perl__.exe manpage) if you want to use PM code in
your application (as Perl/Tk or OpenGL Perl modules
do) without having a text-mode window present.
While using the standard perl.exe from a text-mode
window is possible too, I have seen cases when this
causes degradation of the system stability. Using
perl__.exe avoids such a degradation.
There is no simple way to access WPS objects. The
only way I know is via "OS2::REXX" extension (see the
OS2::REXX manpage), and we do not have access to con
venience methods of Object-REXX. (Is it possible at
all? I know of no Object-REXX API.) The "SOM" exten
sion (currently in alpha-text) may eventually remove
this shortcoming.
Please keep this list up-to-date by informing me about
other items.
Other OSes
Since OS/2 port of perl uses a remarkable EMX environment,
it can run (and build extensions, and - possibly - be
built itself) under any environment which can run EMX. The
current list is DOS, DOS-inside-OS/2, Win0.3*, Win0.95 and
WinNT. Out of many perl flavors, only one works, see the
section on "perl_.exe".
Note that not all features of Perl are available under
these environments. This depends on the features the
extender - most probably RSX - decided to implement.
Cf. the Prerequisites manpage.
Prerequisites
EMX EMX runtime is required (may be substituted by RSX).
Note that it is possible to make perl_.exe to run
under DOS without any external support by binding
emx.exe/rsx.exe to it, see the emxbind manpage. Note
that under DOS for best results one should use RSX
runtime, which has much more functions working (like
"fork", "popen" and so on). In fact RSX is required
if there is no VCPI present. Note the RSX requires
DPMI.
Only the latest runtime is supported, currently
"0.9d fix 03". Perl may run under earlier versions
of EMX, but this is not tested.
One can get different parts of EMX from, say
http://www.leo.org/pub/comp/os/os2/leo/gnu/emx+gcc/
http://powerusersbbs.com/pub/os2/dev/ [EMX+GCC Development]
http://hobbes.nmsu.edu/pub/os2/dev/emx/v0.9d/
The runtime component should have the name
emxrt.zip.
NOTE. It is enough to have emx.exe/rsx.exe on your
path. One does not need to specify them explicitly
(though this
emx perl_.exe -de 0
will work as well.)
RSX To run Perl on DPMI platforms one needs RSX runtime.
This is needed under DOS-inside-OS/2, Win0.3*,
Win0.95 and WinNT (see the section on "Other OSes").
RSX would not work with VCPI only, as EMX would, it
requires DMPI.
Having RSX and the latest sh.exe one gets a fully
functional *nix-ish environment under DOS, say,
"fork", "``" and pipe-"open" work. In fact, Make
Maker works (for static build), so one can have Perl
development environment under DOS.
One can get RSX from, say
ftp://ftp.cdrom.com/pub/os2/emx09c/contrib
ftp://ftp.uni-bielefeld.de/pub/systems/msdos/misc
ftp://ftp.leo.org/pub/comp/os/os2/leo/devtools/emx+gcc/contrib
Contact the author on "rainer@mathematik.uni-biele
feld.de".
The latest sh.exe with DOS hooks is available in
ftp://ftp.math.ohio-state.edu/pub/users/ilya/os2/
as sh_dos.zip or under similar names starting with
"sh", "pdksh" etc.
HPFS Perl does not care about file systems, but to
install the whole perl library intact one needs a
file system which supports long file names.
Note that if you do not plan to build the perl
itself, it may be possible to fool EMX to truncate
file names. This is not supported, read EMX docs to
see how to do it.
pdksh To start external programs with complicated command
lines (like with pipes in between, and/or quoting of
arguments), Perl uses an external shell. With EMX
port such shell should be named sh.exe, and located
either in the wired-in-during-compile locations
(usually F:/bin), or in configurable location (see
the section on "PERL_SH_DIR").
For best results use EMX pdksh. The standard binary
(5.2.14 or later) runs under DOS (with the RSX man
page) as well, see
ftp://ftp.math.ohio-state.edu/pub/users/ilya/os2/
Starting Perl programs under OS/2 (and DOS and...)
Start your Perl program foo.pl with arguments "arg1 arg2
arg3" the same way as on any other platform, by
perl foo.pl arg1 arg2 arg3
If you want to specify perl options "-my_opts" to the perl
itself (as opposed to to your program), use
perl -my_opts foo.pl arg1 arg2 arg3
Alternately, if you use OS/2-ish shell, like CMD or 4os2,
put the following at the start of your perl script:
extproc perl -S -my_opts
rename your program to foo.cmd, and start it by typing
foo arg1 arg2 arg3
Note that because of stupid OS/2 limitations the full path
of the perl script is not available when you use
"extproc", thus you are forced to use "-S" perl switch,
and your script should be on the "PATH". As a plus side,
if you know a full path to your script, you may still
start it with
perl ../../blah/foo.cmd arg1 arg2 arg3
(note that the argument "-my_opts" is taken care of by the
"extproc" line in your script, see the section on
""extproc" on the first line").
To understand what the above magic does, read perl docs
about "-S" switch - see the perlrun manpage, and cmdref
about "extproc":
view perl perlrun
man perlrun
view cmdref extproc
help extproc
or whatever method you prefer.
There are also endless possibilities to use executable
extensions of 4os2, associations of WPS and so on... How
ever, if you use *nixish shell (like sh.exe supplied in
the binary distribution), you need to follow the syntax
specified in the Switches entry in the perlrun manpage.
Note that -S switch enables a search with additional
extensions .cmd, .btm, .bat, .pl as well.
Starting OS/2 (and DOS) programs under Perl
This is what system() (see the system entry in the perl
func manpage), "``" (see the I/O Operators entry in the
perlop manpage), and open pipe (see the open entry in the
perlfunc manpage) are for. (Avoid exec() (see the exec
entry in the perlfunc manpage) unless you know what you
do).
Note however that to use some of these operators you need
to have a sh-syntax shell installed (see the section on
"Pdksh", the section on "Frequently asked questions"), and
perl should be able to find it (see the section on
"PERL_SH_DIR").
The cases when the shell is used are:
1 One-argument system() (see the system entry in the
perlfunc manpage), exec() (see the exec entry in the
perlfunc manpage) with redirection or shell meta-char
acters;
2 Pipe-open (see the open entry in the perlfunc manpage)
with the command which contains redirection or shell
meta-characters;
3 Backticks "``" (see the I/O Operators entry in the
perlop manpage) with the command which contains
redirection or shell meta-characters;
4 If the executable called by system()/exec()/pipe-
open()/"``" is a script with the "magic" "#!" line or
"extproc" line which specifies shell;
5 If the executable called by system()/exec()/pipe-
open()/"``" is a script without "magic" line, and
"$ENV{EXECSHELL}" is set to shell;
6 If the executable called by system()/exec()/pipe-
open()/"``" is not found;
7 For globbing (see the glob entry in the perlfunc man
page, the I/O Operators entry in the perlop manpage).
For the sake of speed for a common case, in the above
algorithms backslashes in the command name are not consid
ered as shell metacharacters.
Perl starts scripts which begin with cookies "extproc" or
"#!" directly, without an intervention of shell. Perl
uses the same algorithm to find the executable as pdksh:
if the path on "#!" line does not work, and contains "/",
then the executable is searched in . and on "PATH". To
find arguments for these scripts Perl uses a different
algorithm than pdksh: up to 3 arguments are recognized,
and trailing whitespace is stripped.
If a script does not contain such a cooky, then to avoid
calling sh.exe, Perl uses the same algorithm as pdksh: if
"$ENV{EXECSHELL}" is set, the script is given as the first
argument to this command, if not set, then "$ENV{COMSPEC}
/c" is used (or a hardwired guess if "$ENV{COMSPEC}" is
not set).
If starting scripts directly, Perl will use exactly the
same algorithm as for the search of script given by -S
command-line option: it will look in the current direc
tory, then on components of "$ENV{PATH}" using the follow
ing order of appended extensions: no extension, .cmd,
.btm, .bat, .pl.
Note that Perl will start to look for scripts only if OS/2
cannot start the specified application, thus "system
'blah'" will not look for a script if there is an exe
cutable file blah.exe anywhere on "PATH".
Note also that executable files on OS/2 can have an arbi
trary extension, but .exe will be automatically appended
if no dot is present in the name. The workaround as as
simple as that: since blah. and blah denote the same
file, to start an executable residing in file n:/bin/blah
(no extension) give an argument "n:/bin/blah." (dot
appended) to system().
Perl will correctly start PM programs from VIO (=text-
mode) Perl process; the opposite is not true: when you
start a non-PM program from a PM Perl process, it would
not run it in a separate session. If a separate session
is desired, either ensure that shell will be used, as in
"system 'cmd /c myprog'", or start it using optional argu
ments to system() documented in "OS2::Process" module.
This is considered to be a feature.
Frequently asked questions
"It does not work"
Perl binary distributions come with a testperl.cmd script
which tries to detect common problems with misconfigured
installations. There is a pretty large chance it will
discover which step of the installation you managed to
goof. ";-)"
I cannot run external programs
Did you run your programs with "-w" switch? See the 2
(and DOS) programs under Perl entry in the Starting OS
manpage.
Do you try to run internal shell commands, like "`copy
a b`" (internal for cmd.exe), or "`glob a*b`" (inter
nal for ksh)? You need to specify your shell explic
itly, like "`cmd /c copy a b`", since Perl cannot
deduce which commands are internal to your shell.
I cannot embed perl into my program, or use perl.dll from
my program.
Is your program EMX-compiled with ""-Zmt -Zcrtdll""?
If not, you need to build a stand-alone DLL for perl.
Contact me, I did it once. Sockets would not work, as
a lot of other stuff.
Did you use the ExtUtils::Embed manpage?
I had reports it does not work. Somebody would need to
fix it.
"``" and pipe-"open" do not work under DOS.
This may a variant of just the section on "I cannot run
external programs", or a deeper problem. Basically: you
need RSX (see the section on "Prerequisites") for these
commands to work, and you may need a port of sh.exe which
understands command arguments. One of such ports is listed
in the section on "Prerequisites" under RSX. Do not forget
to set variable "the section on "PERL_SH_DIR"" as well.
DPMI is required for RSX.
Cannot start "find.exe "pattern" file"
Use one of
system 'cmd', '/c', 'find "pattern" file';
`cmd /c 'find "pattern" file'`
This would start find.exe via cmd.exe via "sh.exe" via
"perl.exe", but this is a price to pay if you want to use
non-conforming program. In fact find.exe cannot be started
at all using C library API only. Otherwise the following
command-lines would be equivalent:
find "pattern" file
find pattern file
INSTALLATION
Automatic binary installation
The most convenient way of installing a binary distribu
tion of perl is via perl installer install.exe. Just fol
low the instructions, and 99% of the installation blues
would go away.
Note however, that you need to have unzip.exe on your
path, and EMX environment running. The latter means that
if you just installed EMX, and made all the needed changes
to Config.sys, you may need to reboot in between. Check
EMX runtime by running
emxrev
A folder is created on your desktop which contains some
useful objects.
Things not taken care of by automatic binary installation:
""PERL_BADLANG""
may be needed if you change your codepage
after perl installation, and the new value
is not supported by EMX. See the section on
"PERL_BADLANG".
""PERL_BADFREE""
see the section on "PERL_BADFREE".
Config.pm This file resides somewhere deep in the
location you installed your perl library,
find it out by
perl -MConfig -le "print $INC{'Config.pm'}"
While most important values in this file
are updated by the binary installer, some
of them may need to be hand-edited. I know
no such data, please keep me informed if
you find one.
NOTE. Because of a typo the binary installer of 5.00305
would install a variable "PERL_SHPATH" into Config.sys.
Please remove this variable and put "the PERL_SH_DIR man
page" instead.
Manual binary installation
As of version 5.00305, OS/2 perl binary distribution comes
split into 11 components. Unfortunately, to enable config
urable binary installation, the file paths in the zip
files are not absolute, but relative to some directory.
Note that the extraction with the stored paths is still
necessary (default with unzip, specify "-d" to pkunzip).
However, you need to know where to extract the files. You
need also to manually change entries in Config.sys to
reflect where did you put the files. Note that if you have
some primitive unzipper (like pkunzip), you may get a lot
of warnings/errors during unzipping. Upgrade to
"(w)unzip".
Below is the sample of what to do to reproduce the config
uration on my machine:
Perl VIO and PM executables (dynamically linked)
unzip perl_exc.zip *.exe *.ico -d f:/emx.add/bin
unzip perl_exc.zip *.dll -d f:/emx.add/dll
(have the directories with "*.exe" on PATH, and "*.dll"
on LIBPATH);
Perl_ VIO executable (statically linked)
unzip perl_aou.zip -d f:/emx.add/bin
(have the directory on PATH);
Executables for Perl utilities
unzip perl_utl.zip -d f:/emx.add/bin
(have the directory on PATH);
Main Perl library
unzip perl_mlb.zip -d f:/perllib/lib
If this directory is exactly the same as the prefix
which was compiled into perl.exe, you do not need to
change anything. However, for perl to find the library
if you use a different path, you need to "set PERL
LIB_PREFIX" in Config.sys, see the section on "PERL
LIB_PREFIX".
Additional Perl modules
unzip perl_ste.zip -d f:/perllib/lib/site_perl/5.8.3/
Same remark as above applies. Additionally, if this
directory is not one of directories on @INC (and @INC
is influenced by "PERLLIB_PREFIX"), you need to put
this directory and subdirectory ./os2 in "PERLLIB" or
"PERL5LIB" variable. Do not use "PERL5LIB" unless you
have it set already. See the ENVIRONMENT entry in the
perl manpage.
Tools to compile Perl modules
unzip perl_blb.zip -d f:/perllib/lib
Same remark as for perl_ste.zip.
Manpages for Perl and utilities
unzip perl_man.zip -d f:/perllib/man
This directory should better be on "MANPATH". You need
to have a working man to access these files.
Manpages for Perl modules
unzip perl_mam.zip -d f:/perllib/man
This directory should better be on "MANPATH". You need
to have a working man to access these files.
Source for Perl documentation
unzip perl_pod.zip -d f:/perllib/lib
This is used by the "perldoc" program (see the perldoc
manpage), and may be used to generate HTML documenta
tion usable by WWW browsers, and documentation in zil
lions of other formats: "info", "LaTeX", "Acrobat",
"FrameMaker" and so on.
Perl manual in .INF format
unzip perl_inf.zip -d d:/os2/book
This directory should better be on "BOOKSHELF".
Pdksh
unzip perl_sh.zip -d f:/bin
This is used by perl to run external commands which
explicitly require shell, like the commands using redi_
rection and shell metacharacters. It is also used
instead of explicit /bin/sh.
Set "PERL_SH_DIR" (see the section on "PERL_SH_DIR") if
you move sh.exe from the above location.
Note. It may be possible to use some other sh-compati
ble shell (file globbing - if done via shell - may
break).
After you installed the components you needed and updated
the Config.sys correspondingly, you need to hand-edit Con_
fig.pm. This file resides somewhere deep in the location
you installed your perl library, find it out by
perl -MConfig -le "print $INC{'Config.pm'}"
You need to correct all the entries which look like file
paths (they currently start with "f:/").
Warning
The automatic and manual perl installation leave precom
piled paths inside perl executables. While these paths are
overwriteable (see the section on "PERLLIB_PREFIX", the
section on "PERL_SH_DIR"), one may get better results by
binary editing of paths inside the executables/DLLs.
Accessing documentation
Depending on how you built/installed perl you may have
(otherwise identical) Perl documentation in the following
formats:
OS/2 .INF file
Most probably the most convenient form. Under OS/2 view it
as
view perl
view perl perlfunc
view perl less
view perl ExtUtils::MakeMaker
(currently the last two may hit a wrong location, but this
may improve soon). Under Win* see the section on "SYNOP
SIS".
If you want to build the docs yourself, and have OS/2
toolkit, run
pod2ipf > perl.ipf
in /perllib/lib/pod directory, then
ipfc /inf perl.ipf
(Expect a lot of errors during the both steps.) Now move
it on your BOOKSHELF path.
Plain text
If you have perl documentation in the source form, perl
utilities installed, and GNU groff installed, you may use
perldoc perlfunc
perldoc less
perldoc ExtUtils::MakeMaker
to access the perl documentation in the text form (note
that you may get better results using perl manpages).
Alternately, try running pod2text on .pod files.
Manpages
If you have man installed on your system, and you
installed perl manpages, use something like this:
man perlfunc
man 3 less
man ExtUtils.MakeMaker
to access documentation for different components of Perl.
Start with
man perl
Note that dot (.) is used as a package separator for docu
mentation for packages, and as usual, sometimes you need
to give the section - "3" above - to avoid shadowing by
the less(1) manpage.
Make sure that the directory above the directory with man
pages is on our "MANPATH", like this
set MANPATH=c:/man;f:/perllib/man
for Perl manpages in "f:/perllib/man/man1/" etc.
HTML
If you have some WWW browser available, installed the Perl
documentation in the source form, and Perl utilities, you
can build HTML docs. Cd to directory with .pod files, and
do like this
cd f:/perllib/lib/pod
pod2html
After this you can direct your browser the file perl.html
in this directory, and go ahead with reading docs, like
this:
explore file:///f:/perllib/lib/pod/perl.html
Alternatively you may be able to get these docs prebuilt
from CPAN.
GNU "info" files
Users of Emacs would appreciate it very much, especially
with "CPerl" mode loaded. You need to get latest
"pod2info" from "CPAN", or, alternately, prebuilt info
pages.
for "Acrobat" are available on CPAN (for slightly old ver
sion of perl).
"LaTeX" docs
can be constructed using "pod2latex".
BUILD
Here we discuss how to build Perl under OS/2. There is an
alternative (but maybe older) view on
http://www.shadow.net/~troc/os2perl.html
The short story
Assume that you are a seasoned porter, so are sure that
all the necessary tools are already present on your sys
tem, and you know how to get the Perl source distribution.
Untar it, change to the extract directory, and
gnupatch -p0 < os2\diff.configure
sh Configure -des -D prefix=f:/perllib
make
make test
make install
make aout_test
make aout_install
This puts the executables in f:/perllib/bin. Manually
move them to the "PATH", manually move the built perl*.dll
to "LIBPATH" (here * is a not-very-meaningful hex check
sum), and run
make installcmd INSTALLCMDDIR=d:/ir/on/path
What follows is a detailed guide through these steps.
Prerequisites
You need to have the latest EMX development environment,
the full GNU tool suite (gawk renamed to awk, and GNU
find.exe earlier on path than the OS/2 find.exe, same with
sort.exe, to check use
find --version
sort --version
). You need the latest version of pdksh installed as
sh.exe.
Check that you have BSD libraries and headers installed,
and - optionally - Berkeley DB headers and libraries, and
crypt.
Possible locations to get this from are
ftp://hobbes.nmsu.edu/os2/unix/
ftp://ftp.cdrom.com/pub/os2/unix/
ftp://ftp.cdrom.com/pub/os2/dev32/
ftp://ftp.cdrom.com/pub/os2/emx09c/
It is reported that the following archives contain enough
utils to build perl: gnufutil.zip, gnusutil.zip, gnutu_
til.zip, gnused.zip, gnupatch.zip, gnuawk.zip, gnu_
make.zip, bsddev.zip and ksh527rt.zip (or a later ver
sion). Note that all these utilities are known to be
available from LEO:
ftp://ftp.leo.org/pub/comp/os/os2/leo/gnu
If you have exactly the same version of Perl installed
already, make sure that no copies or perl are currently
running. Later steps of the build may fail since an older
version of perl.dll loaded into memory may be found.
Also make sure that you have /tmp directory on the current
drive, and . directory in your "LIBPATH". One may try to
correct the latter condition by
set BEGINLIBPATH .
if you use something like CMD.EXE or latest versions of
4os2.exe.
Make sure your gcc is good for "-Zomf" linking: run
"omflibs" script in /emx/lib directory.
Check that you have link386 installed. It comes standard
with OS/2, but may be not installed due to customization.
If typing
link386
shows you do not have it, do Selective install, and choose
"Link object modules" in Optional system utilities/More.
If you get into link386 prompts, press "Ctrl-C" to exit.
Getting perl source
You need to fetch the latest perl source (including devel
opers releases). With some probability it is located in
http://www.perl.com/CPAN/src/5.0
http://www.perl.com/CPAN/src/5.0/unsupported
If not, you may need to dig in the indices to find it in
the directory of the current maintainer.
Quick cycle of developers release may break the OS/2 build
time to time, looking into
http://www.perl.com/CPAN/ports/os2/ilyaz/
may indicate the latest release which was publicly
released by the maintainer. Note that the release may
include some additional patches to apply to the current
source of perl.
Extract it like this
tar vzxf perl5.00409.tar.gz
You may see a message about errors while extracting Con_
figure. This is because there is a conflict with a simi
larly-named file configure.
Change to the directory of extraction.
Application of the patches
You need to apply the patches in ./os2/diff.* like this:
gnupatch -p0 < os2\diff.configure
You may also need to apply the patches supplied with the
binary distribution of perl.
Note also that the db.lib and db.a from the EMX distribu
tion are not suitable for multi-threaded compile (even
single-threaded flavor of Perl uses multi-threaded C RTL,
for compatibility with XFree86-OS/2). Get a corrected one
from
ftp://ftp.math.ohio-state.edu/pub/users/ilya/os2/db_mt.zip
Hand-editing
You may look into the file ./hints/os2.sh and correct any
thing wrong you find there. I do not expect it is needed
anywhere.
Making
sh Configure -des -D prefix=f:/perllib
"prefix" means: where to install the resulting perl
library. Giving correct prefix you may avoid the need to
specify "PERLLIB_PREFIX", see the section on "PERLLIB_PRE
FIX".
Ignore the message about missing "ln", and about "-c"
option to tr. The latter is most probably already fixed,
if you see it and can trace where the latter spurious
warning comes from, please inform me.
Now
make
At some moment the built may die, reporting a version mis_
match or unable to run perl. This means that you do not
have . in your LIBPATH, so perl.exe cannot find the needed
perl67B2.dll (treat these hex digits as line noise).
After this is fixed the build should finish without a lot
of fuss.
Testing
Now run
make test
All tests should succeed (with some of them skipped).
Some tests may generate extra messages similar to
A lot of ""bad free""
in database tests related to Berkeley DB. This should
be fixed already. If it persists, you may disable
this warnings, see the section on "PERL_BADFREE".
Process terminated by SIGTERM/SIGINT
This is a standard message issued by OS/2 applica
tions. *nix applications die in silence. It is consid
ered to be a feature. One can easily disable this by
appropriate sighandlers.
However the test engine bleeds these message to screen
in unexpected moments. Two messages of this kind
should be present during testing.
To get finer test reports, call
perl t/harness
The report with io/pipe.t failing may look like this:
Failed Test Status Wstat Total Fail Failed List of failed
------------------------------------------------------------
io/pipe.t 12 1 8.33% 9
7 tests skipped, plus 56 subtests skipped.
Failed 1/195 test scripts, 99.49% okay. 1/6542 subtests failed, 99.98% okay.
The reasons for most important skipped tests are:
op/fs.t
18 Checks "atime" and "mtime" of "stat()" -
unfortunately, HPFS provides only 2sec time
granularity (for compatibility with FAT?).
25 Checks "truncate()" on a filehandle just
opened for write - I do not know why this
should or should not work.
op/stat.t
Checks "stat()". Tests:
4 Checks "atime" and "mtime" of "stat()" -
unfortunately, HPFS provides only 2sec time
granularity (for compatibility with FAT?).
Installing the built perl
If you haven't yet moved perl.dll onto LIBPATH, do it now.
Run
make install
It would put the generated files into needed locations.
Manually put perl.exe, perl__.exe and perl___.exe to a
location on your PATH, perl.dll to a location on your LIB
PATH.
Run
make installcmd INSTALLCMDDIR=d:/ir/on/path
to convert perl utilities to .cmd files and put them on
PATH. You need to put .EXE-utilities on path manually.
They are installed in "$prefix/bin", here "$prefix" is
what you gave to Configure, see the Making manpage.
"a.out"-style build
Proceed as above, but make perl_.exe (see the section on
"perl_.exe") by
make perl_
test and install by
make aout_test
make aout_install
Manually put perl_.exe to a location on your PATH.
Note. The build process for "perl_" does not know about
all the dependencies, so you should make sure that any
thing is up-to-date, say, by doing
make perl_dll
first.
Build FAQ
Some "/" became "\" in pdksh.
You have a very old pdksh. See the Prerequisites manpage.
"'errno'" - unresolved external
You do not have MT-safe db.lib. See the Prerequisites man
page.
Problems with tr or sed
reported with very old version of tr and sed.
Some problem (forget which ;-)
You have an older version of perl.dll on your LIBPATH,
which broke the build of extensions.
Library ... not found
You did not run "omflibs". See the Prerequisites manpage.
Segfault in make
You use an old version of GNU make. See the Prerequisites
manpage.
op/sprintf test failure
This can result from a bug in emx sprintf which was fixed
in 0.9d fix 03.
Specific (mis)features of OS/2 port
"setpriority", "getpriority"
Note that these functions are compatible with *nix, not
with the older ports of '94 - 95. The priorities are abso
lute, go from 32 to -95, lower is quicker. 0 is the
default priority.
WARNING. Calling "getpriority" on a non-existing process
can lock the system before Warp3 fixpak22.
"system()"
Multi-argument form of "system()" allows an additional
numeric argument. The meaning of this argument is
described in the OS2::Process manpage.
When finding a program to run, Perl first asks the OS to
look for executables on "PATH". If not found, it looks
for a script with possible extensions added in this order:
no extension, .cmd, .btm, .bat, .pl. If found, Perl
checks the start of the file for magic strings ""#!"" and
""extproc "". If found, Perl uses the rest of the first
line as the beginning of the command line to run this
script. The only mangling done to the first line is
extraction of arguments (currently up to 3), and ignoring
of the path-part of the "interpreter" name if it can't be
found using the full path.
E.g., "system 'foo', 'bar', 'baz'" may lead Perl to find
ing C:/emx/bin/foo.cmd with the first line being
extproc /bin/bash -x-c
If /bin/bash is not found, and appending of executable
extensions to /bin/bash does not help either, then Perl
looks for an executable bash on "PATH". If found in
C:/emx.add/bin/bash.exe, then the above system() is trans
lated to
system qw(C:/emx.add/bin/bash.exe -x -c C:/emx/bin/foo.cmd bar baz)
One additional translation is performed: instead of
/bin/sh Perl uses the hardwired-or-customized shell (see
"the section on "PERL_SH_DIR"").
The above search for "interpreter" is recursive: if bash
executable is not found, but bash.btm is found, Perl will
investigate its first line etc. The only hardwired limit
on the recursion depth is implicit: there is a limit 4 on
the number of additional arguments inserted before the
actual arguments given to system(). In particular, if no
additional arguments are specified on the "magic" first
lines, then the limit on the depth is 4.
If Perl finds that the found executable is of different
type than the current session, it will start the new pro
cess in a separate session of necessary type. Call via
"OS2::Process" to disable this magic.
"extproc" on the first line
If the first chars of a Perl script are ""extproc "", this
line is treated as "#!"-line, thus all the switches on
this line are processed (twice if script was started via
cmd.exe). See the DESCRIPTION entry in the perlrun man
page.
Additional modules:
the OS2::Process manpage, the OS2::DLL manpage, the
OS2::REXX manpage, the OS2::PrfDB manpage, the
OS2::ExtAttr manpage. These modules provide access to
additional numeric argument for "system" and to the infor
mation about the running process, to DLLs having functions
with REXX signature and to the REXX runtime, to OS/2
databases in the .INI format, and to Extended Attributes.
Two additional extensions by Andreas Kaiser, "OS2::UPM",
and "OS2::FTP", are included into "ILYAZ" directory, mir
rored on CPAN.
Prebuilt methods:
""File::Copy::syscopy""
used by "File::Copy::copy", see the File::Copy man
page.
""DynaLoader::mod2fname""
used by "DynaLoader" for DLL name mangling.
""Cwd::current_drive()""
Self explanatory.
""Cwd::sys_chdir(name)""
leaves drive as it is.
""Cwd::change_drive(name)""
chanes the "current" drive.
""Cwd::sys_is_absolute(name)""
means has drive letter and is_rooted.
""Cwd::sys_is_rooted(name)""
means has leading "[/\\]" (maybe after a drive-let
ter:).
""Cwd::sys_is_relative(name)""
means changes with current dir.
""Cwd::sys_cwd(name)""
Interface to cwd from EMX. Used by "Cwd::cwd".
""Cwd::sys_abspath(name, dir)""
Really really odious function to implement. Returns
absolute name of file which would have "name" if CWD
were "dir". "Dir" defaults to the current dir.
""Cwd::extLibpath([type])""
Get current value of extended library search path. If
"type" is present and true, works with END_LIBPATH,
otherwise with "BEGIN_LIBPATH".
""Cwd::extLibpath_set( path [, type ] )""
Set current value of extended library search path. If
"type" is present and true, works with END_LIBPATH,
otherwise with "BEGIN_LIBPATH".
""OS2::Error(do_harderror,do_exception)""
Returns "undef" if it was not called yet, otherwise
bit 1 is set if on the previous call do_harderror was
enabled, bit 2 is set if if on previous call do_excep
tion was enabled.
This function enables/disables error popups associated
with hardware errors (Disk not ready etc.) and soft
ware exceptions.
I know of no way to find out the state of popups
before the first call to this function.
""OS2::Errors2Drive(drive)""
Returns "undef" if it was not called yet, otherwise
return false if errors were not requested to be writ
ten to a hard drive, or the drive letter if this was
requested.
This function may redirect error popups associated
with hardware errors (Disk not ready etc.) and soft
ware exceptions to the file POPUPLOG.OS2 at the root
directory of the specified drive. Overrides
OS2:\fIs0:Error() specified by individual programs.
Given argument undef will disable redirection.
Has global effect, persists after the application
exits.
I know of no way to find out the state of redirection
of popups to the disk before the first call to this
function.
OS2:s0:SysInfo()
Returns a hash with system information. The keys of
the hash are
MAX_PATH_LENGTH, MAX_TEXT_SESSIONS, MAX_PM_SESSIONS,
MAX_VDM_SESSIONS, BOOT_DRIVE, DYN_PRI_VARIATION,
MAX_WAIT, MIN_SLICE, MAX_SLICE, PAGE_SIZE,
VERSION_MAJOR, VERSION_MINOR, VERSION_REVISION,
MS_COUNT, TIME_LOW, TIME_HIGH, TOTPHYSMEM, TOTRESMEM,
TOTAVAILMEM, MAXPRMEM, MAXSHMEM, TIMER_INTERVAL,
MAX_COMP_LENGTH, FOREGROUND_FS_SESSION,
FOREGROUND_PROCESS
OS2:s0:BootDrive()
Returns a letter without colon.
""OS2::MorphPM(serve)"", ""OS2::UnMorphPM(serve)""
Transforms the current application into a PM applica
tion and back. The argument true means that a real
message loop is going to be served. OS2:\fIs0:Mor
phPM() returns the PM message queue handle as an inte
ger.
See the section on "Centralized management of
resources" for additional details.
""OS2::Serve_Messages(force)""
Fake on-demand retrieval of outstanding PM messages.
If "force" is false, will not dispatch messages if a
real message loop is known to be present. Returns
number of messages retrieved.
Dies with "QUITing..." if WM_QUIT message is obtained.
""OS2::Process_Messages(force [, cnt])""
Retrieval of PM messages until window cre
ation/destruction. If "force" is false, will not dis
patch messages if a real message loop is known to be
present.
Returns change in number of windows. If "cnt" is
given, it is incremented by the number of messages
retrieved.
Dies with "QUITing..." if WM_QUIT message is obtained.
""OS2::_control87(new,mask)""
the same as _control87(3) of EMX. Takes integers as
arguments, returns the previous coprocessor control
word as an integer. Only bits in "new" which are pre
sent in "mask" are changed in the control word.
OS2:s0:get_control87()
gets the coprocessor control word as an integer.
""OS2::set_control87_em(new=MCW_EM,mask=MCW_EM)""
The variant of OS2:\fIs0:_control87() with default
values good for handling exception mask: if no "mask",
uses exception mask part of "new" only. If no "new",
disables all the floating point exceptions.
See the section on "Misfeatures" for details.
(Note that some of these may be moved to different
libraries - eventually).
Prebuilt variables:
$OS2::emx_rev
same as _emx_rev of EMX, a string similar to "0.9c".
$OS2::emx_env
same as _emx_env of EMX, a number similar to 0x8001.
$OS2::os_ver
a number "OS_MAJOR + 0.001 * OS_MINOR".
Misfeatures
Since flock(3) is present in EMX, but is not func
tional, it is emulated by perl. To disable the emula
tions, set environment variable "USE_PERL_FLOCK=0".
Here is the list of things which may be "broken" on
EMX (from EMX docs):
The functions recvmsg(3), sendmsg(3), and socket_
pair(3) are not implemented.
sock_init(3) is not required and not implemented.
flock(3) is not yet implemented (dummy function).
(Perl has a workaround.)
kill(3): Special treatment of PID=0, PID=1 and
PID=-1 is not implemented.
waitpid(3):
WUNTRACED
Not implemented.
waitpid() is not implemented for negative values of PID.
Note that "kill -9" does not work with the current
version of EMX.
Since sh.exe is used for globing (see the glob entry
in the perlfunc manpage), the bugs of sh.exe plague
perl as well.
In particular, uppercase letters do not work in
"[...]"-patterns with the current pdksh.
Unix-domain sockets on OS/2 live in a pseudo-file-sys
tem "/sockets/...". To avoid a failure to create a
socket with a name of a different form, ""/socket/""
is prepended to the socket name (unless it starts with
this already).
This may lead to problems later in case the socket is
accessed via the "usual" file-system calls using the
"initial" name.
Apparently, IBM used a compiler (for some period of
time around '95?) which changes FP mask right and
left. This is not that bad for IBM's programs, but
the same compiler was used for DLLs which are used
with general-purpose applications. When these DLLs
are used, the state of floating-point flags in the
application is not predictable.
What is much worse, some DLLs change the floating
point flags when in _DLLInitTerm() (e.g., TCP32IP).
This means that even if you do not call any function
in the DLL, just the act of loading this DLL will
reset your flags. What is worse, the same compiler
was used to compile some HOOK DLLs. Given that HOOK
dlls are executed in the context of all the applica
tions in the system, this means a complete unpre
dictablity of floating point flags on systems using
such HOOK DLLs. E.g., GAMESRVR.DLL of DIVE origin
changes the floating point flags on each write to the
TTY of a VIO (windowed text-mode) applications.
Some other (not completely debugged) situations when
FP flags change include some video drivers (?), and
some operations related to creation of the windows.
People who code OpenGL may have more experience on
this.
Perl is generally used in the situation when all the
floating-point exceptions are ignored, as is the
default under EMX. If they are not ignored, some
benign Perl programs would get a "SIGFPE" and would
die a horrible death.
To circumvent this, Perl uses two hacks. They help
against one type of damage only: FP flags changed when
loading a DLL.
One of the hacks is to disable floating point excep
tions on startup (as is the default with EMX). This
helps only with compile-time-linked DLLs changing the
flags before main() had a chance to be called.
The other hack is to restore FP flags after a call to
dlopen(). This helps against similar damage done by
DLLs _DLLInitTerm() at runtime. Currently no way to
switch these hacks off is provided.
Modifications
Perl modifies some standard C library calls in the follow
ing ways:
""popen""
"my_popen" uses sh.exe if shell is required, cf.
the section on "PERL_SH_DIR".
""tmpnam""
is created using "TMP" or "TEMP" environment
variable, via "tempnam".
""tmpfile""
If the current directory is not writable, file is
created using modified "tmpnam", so there may be
a race condition.
""ctermid""
a dummy implementation.
""stat"" "os2_stat" special-cases /dev/tty and /dev/con.
""mkdir"", ""rmdir""
these EMX functions do not work if the path con
tains a trailing "/". Perl contains a workaround
for this.
""flock""
Since flock(3) is present in EMX, but is not
functional, it is emulated by perl. To disable
the emulations, set environment variable
"USE_PERL_FLOCK=0".
Identifying DLLs
All the DLLs built with the current versions of Perl have
ID strings identifying the name of the extension, its ver
sion, and the version of Perl required for this DLL. Run
"bldlevel DLL-name" to find this info.
Centralized management of resources
Since to call certain OS/2 API one needs to have a cor
rectly initialized "Win" subsystem, OS/2-specific exten
sions may require getting "HAB"s and "HMQ"s. If an exten
sion would do it on its own, another extension could fail
to initialize.
Perl provides a centralized management of these resources:
""HAB""
To get the HAB, the extension should call "hab =
perl_hab_GET()" in C. After this call is performed,
"hab" may be accessed as "Perl_hab". There is no need
to release the HAB after it is used.
If by some reasons perl.h cannot be included, use
extern int Perl_hab_GET(void);
instead.
""HMQ""
There are two cases:
the extension needs an "HMQ" only because some API
will not work otherwise. Use "serve = 0" below.
the extension needs an "HMQ" since it wants to
engage in a PM event loop. Use "serve = 1" below.
To get an "HMQ", the extension should call "hmq =
perl_hmq_GET(serve)" in C. After this call is per
formed, "hmq" may be accessed as "Perl_hmq".
To signal to Perl that HMQ is not needed any more,
call "perl_hmq_UNSET(serve)". Perl process will auto
matically morph/unmorph itself into/from a PM process
if HMQ is needed/not-needed. Perl will automatically
enable/disable "WM_QUIT" message during shutdown if
the message queue is served/not-served.
NOTE. If during a shutdown there is a message queue
which did not disable WM_QUIT, and which did not pro
cess the received WM_QUIT message, the shutdown will
be automatically cancelled. Do not call
"perl_hmq_GET(1)" unless you are going to process mes
sages on an orderly basis.
Perl flavors
Because of idiosyncrasies of OS/2 one cannot have all the
eggs in the same basket (though EMX environment tries hard
to overcome this limitations, so the situation may somehow
improve). There are 4 executables for Perl provided by the
distribution:
perl.exe
The main workhorse. This is a chimera executable: it is
compiled as an "a.out"-style executable, but is linked
with "omf"-style dynamic library perl.dll, and with
dynamic CRT DLL. This executable is a VIO application.
It can load perl dynamic extensions, and it can fork().
Note. Keep in mind that fork() is needed to open a pipe to
yourself.
perl_.exe
This is a statically linked "a.out"-style executable. It
cannot load dynamic Perl extensions. The executable sup
plied in binary distributions has a lot of extensions pre
built, thus the above restriction is important only if you
use custom-built extensions. This executable is a VIO
application.
This is the only executable with does not require OS/2.
The friends locked into "M$" world would appreciate the
fact that this executable runs under DOS, Win0.3*, Win0.95
and WinNT with an appropriate extender. See the section on
"Other OSes".
perl__.exe
This is the same executable as perl___.exe, but it is a PM
application.
Note. Usually (unless explicitly redirected during the
startup) STDIN, STDERR, and STDOUT of a PM application are
redirected to nul. However, it is possible to see them if
you start "perl__.exe" from a PM program which emulates a
console window, like Shell mode of Emacs or EPM. Thus it
is possible to use Perl debugger (see the perldebug man
page) to debug your PM application (but beware of the mes
sage loop lockups - this will not work if you have a mes
sage queue to serve, unless you hook the serving into the
getc() function of the debugger).
Another way to see the output of a PM program is to run it
as
pm_prog args 2>&1 | cat -
with a shell different from cmd.exe, so that it does not
create a link between a VIO session and the session of
"pm_porg". (Such a link closes the VIO window.) E.g.,
this works with sh.exe - or with Perl!
open P, 'pm_prog args 2>&1 |' or die;
print while <P>;
The flavor perl__.exe is required if you want to start
your program without a VIO window present, but not
"detach"ed (run "help detach" for more info). Very useful
for extensions which use PM, like "Perl/Tk" or "OpenGL".
perl___.exe
This is an "omf"-style executable which is dynamically
linked to perl.dll and CRT DLL. I know no advantages of
this executable over "perl.exe", but it cannot fork() at
all. Well, one advantage is that the build process is not
so convoluted as with "perl.exe".
It is a VIO application.
Why strange names?
Since Perl processes the "#!"-line (cf. the DESCRIPTION
entry in the perlrun manpage, the Switches entry in the
perlrun manpage, the Not a perl script entry in the perl
diag manpage, the No Perl script found in input entry in
the perldiag manpage), it should know when a program is a
Perl. There is some naming convention which allows Perl to
distinguish correct lines from wrong ones. The above names
are almost the only names allowed by this convention which
do not contain digits (which have absolutely different
semantics).
Why dynamic linking?
Well, having several executables dynamically linked to the
same huge library has its advantages, but this would not
substantiate the additional work to make it compile. The
reason is the complicated-to-developers but very quick and
convenient-to-users "hard" dynamic linking used by OS/2.
There are two distinctive features of the dyna-linking
model of OS/2: all the references to external functions
are resolved at the compile time; there is no runtime
fixup of the DLLs after they are loaded into memory. The
first feature is an enormous advantage over other models:
it avoids conflicts when several DLLs used by an applica
tion export entries with the same name. In such cases
"other" models of dyna-linking just choose between these
two entry points using some random criterion - with pre
dictable disasters as results. But it is the second fea
ture which requires the build of perl.dll.
The address tables of DLLs are patched only once, when
they are loaded. The addresses of the entry points into
DLLs are guaranteed to be the same for all the programs
which use the same DLL. This removes the runtime fixup -
once DLL is loaded, its code is read-only.
While this allows some (significant?) performance advan
tages, this makes life much harder for developers, since
the above scheme makes it impossible for a DLL to be
"linked" to a symbol in the .EXE file. Indeed, this would
need a DLL to have different relocations tables for the
(different) executables which use this DLL.
However, a dynamically loaded Perl extension is forced to
use some symbols from the perl executable, e.g., to know
how to find the arguments to the functions: the arguments
live on the perl internal evaluation stack. The solution
is to put the main code of the interpreter into a DLL, and
make the .EXE file which just loads this DLL into memory
and supplies command-arguments. The extension DLL cannot
link to symbols in .EXE, but it has no problem linking to
symbols in the .DLL.
This greatly increases the load time for the application
(as well as complexity of the compilation). Since inter
preter is in a DLL, the C RTL is basically forced to
reside in a DLL as well (otherwise extensions would not be
able to use CRT). There are some advantages if you use
different flavors of perl, such as running perl.exe and
perl__.exe simultaneously: they share the memory of
perl.dll.
NOTE. There is one additional effect which makes DLLs
more wasteful: DLLs are loaded in the shared memory
region, which is a scarse resource given the 512M barrier
of the "standard" OS/2 virtual memory. The code of .EXE
files is also shared by all the processes which use the
particular .EXE, but they are "shared in the private
address space of the process"; this is possible because
the address at which different sections of the .EXE file
are loaded is decided at compile-time, thus all the pro
cesses have these sections loaded at same addresses, and
no fixup of internal links inside the .EXE is needed.
Since DLLs may be loaded at run time, to have the same
mechanism for for DLLs one needs to have the address range
of any of the loaded DLLs in the system to be available in
all the processes which did not load a particular DLL yet.
This is why the DLLs are mapped to the shared memory
region.
Why chimera build?
Current EMX environment does not allow DLLs compiled using
Unixish "a.out" format to export symbols for data (or at
least some types of data). This forces "omf"-style compile
of perl.dll.
Current EMX environment does not allow .EXE files compiled
in "omf" format to fork(). fork() is needed for exactly
three Perl operations:
explicit fork() in the script,
"open FH, "|-""
"open FH, "-|"", in other words, opening pipes to
itself.
While these operations are not questions of life and
death, they are needed for a lot of useful scripts. This
forces "a.out"-style compile of perl.exe.
ENVIRONMENT
Here we list environment variables with are either OS/2-
and DOS- and Win*-specific, or are more important under
OS/2 than under other OSes.
"PERLLIB_PREFIX"
Specific for EMX port. Should have the form
path1;path2
or
path1 path2
If the beginning of some prebuilt path matches path1, it
is substituted with path2.
Should be used if the perl library is moved from the
default location in preference to "PERL(5)LIB", since this
would not leave wrong entries in @INC. For example, if
the compiled version of perl looks for @INC in f:/perl_
lib/lib, and you want to install the library in
h:/opt/gnu, do
set PERLLIB_PREFIX=f:/perllib/lib;h:/opt/gnu
This will cause Perl with the prebuilt @INC of
f:/perllib/lib/5.00553/os2
f:/perllib/lib/5.00553
f:/perllib/lib/site_perl/5.00553/os2
f:/perllib/lib/site_perl/5.00553
.
to use the following @INC:
h:/opt/gnu/5.00553/os2
h:/opt/gnu/5.00553
h:/opt/gnu/site_perl/5.00553/os2
h:/opt/gnu/site_perl/5.00553
.
"PERL_BADLANG"
If 0, perl ignores setlocale() failing. May be useful with
some strange locales.
"PERL_BADFREE"
If 0, perl would not warn of in case of unwarranted
free(). With older perls this might be useful in conjunc
tion with the module DB_File, which was buggy when
dynamically linked and OMF-built.
Should not be set with newer Perls, since this may hide
some real problems.
"PERL_SH_DIR"
Specific for EMX port. Gives the directory part of the
location for sh.exe.
"USE_PERL_FLOCK"
Specific for EMX port. Since flock(3) is present in EMX,
but is not functional, it is emulated by perl. To disable
the emulations, set environment variable
"USE_PERL_FLOCK=0".
"TMP" or "TEMP"
Specific for EMX port. Used as storage place for temporary
files.
Evolution
Here we list major changes which could make you by sur
prise.
Priorities
"setpriority" and "getpriority" are not compatible with
earlier ports by Andreas Kaiser. See ""setpriority, get
priority"".
DLL name mangling
With the release 5.003_01 the dynamically loadable
libraries should be rebuilt when a different version of
Perl is compiled. In particular, DLLs (including perl.dll)
are now created with the names which contain a checksum,
thus allowing workaround for OS/2 scheme of caching DLLs.
It may be possible to code a simple workaround which would
find the old DLLs looking through the old @INC;
mangle the names according to the scheme of new perl
and copy the DLLs to these names;
edit the internal "LX" tables of DLL to reflect the
change of the name (probably not needed for Perl
extension DLLs, since the internally coded names are
not used for "specific" DLLs, they used only for
"global" DLLs).
edit the internal "IMPORT" tables and change the name
of the "old" perl????.dll to the "new" perl????.dll.
Threading
As of release 5.003_01 perl is linked to multithreaded C
RTL DLL. If perl itself is not compiled multithread-
enabled, so will not be perl's malloc(). However, exten
sions may use multiple thread on their own risk.
This was needed to compile "Perl/Tk" for XFree86-OS/2 out-
of-the-box, and link with DLLs for other useful libraries,
which typically are compiled with "-Zmt -Zcrtdll".
Calls to external programs
Due to a popular demand the perl external program calling
has been changed wrt Andreas Kaiser's port. If perl needs
to call an external program via shell, the f:/bin/sh.exe
will be called, or whatever is the override, see the sec
tion on "PERL_SH_DIR".
Thus means that you need to get some copy of a sh.exe as
well (I use one from pdksh). The path F:/bin above is set
up automatically during the build to a correct value on
the builder machine, but is overridable at runtime,
Reasons: a consensus on "perl5-porters" was that perl
should use one non-overridable shell per platform. The
obvious choices for OS/2 are cmd.exe and sh.exe. Having
perl build itself would be impossible with cmd.exe as a
shell, thus I picked up "sh.exe". This assures almost 100%
compatibility with the scripts coming from *nix. As an
added benefit this works as well under DOS if you use DOS-
enabled port of pdksh (see the section on "Prerequi
sites").
Disadvantages: currently sh.exe of pdksh calls external
programs via fork()/exec(), and there is no functioning
exec() on OS/2. exec() is emulated by EMX by an asyn
chronous call while the caller waits for child completion
(to pretend that the "pid" did not change). This means
that 1 extra copy of sh.exe is made active via
fork()/exec(), which may lead to some resources taken from
the system (even if we do not count extra work needed for
fork()ing).
Note that this a lesser issue now when we do not spawn
sh.exe unless needed (metachars found).
One can always start cmd.exe explicitly via
system 'cmd', '/c', 'mycmd', 'arg1', 'arg2', ...
If you need to use cmd.exe, and do not want to hand-edit
thousands of your scripts, the long-term solution proposed
on p5-p is to have a directive
use OS2::Cmd;
which will override system(), exec(), "``", and
"open(,'...|')". With current perl you may override only
system(), readpipe() - the explicit version of "``", and
maybe exec(). The code will substitute the one-argument
call to system() by "CORE::system('cmd.exe', '/c',
shift)".
If you have some working code for "OS2::Cmd", please send
it to me, I will include it into distribution. I have no
need for such a module, so cannot test it.
For the details of the current situation with calling
external programs, see the 2 (and DOS) programs under Perl
entry in the Starting OS manpage. Set us mention a couple
of features:
External scripts may be called by their basename.
Perl will try the same extensions as when processing
-S command-line switch.
External scripts starting with "#!" or "extproc " will
be executed directly, without calling the shell, by
calling the program specified on the rest of the first
line.
Memory allocation
Perl uses its own malloc() under OS/2 - interpreters are
usually malloc-bound for speed, but perl is not, since its
malloc is lightning-fast. Perl-memory-usage-tuned bench
marks show that Perl's malloc is 5 times quicker than EMX
one. I do not have convincing data about memory foot
print, but a (pretty random) benchmark showed that Perl's
one is 5% better.
Combination of perl's malloc() and rigid DLL name resolu
tion creates a special problem with library functions
which expect their return value to be free()d by system's
free(). To facilitate extensions which need to call such
functions, system memory-allocation functions are still
available with the prefix "emx_" added. (Currently only
DLL perl has this, it should propagate to perl_.exe
shortly.)
Threads
One can build perl with thread support enabled by provid
ing "-D usethreads" option to Configure. Currently OS/2
support of threads is very preliminary.
Most notable problems:
""COND_WAIT""
may have a race condition. Needs a reimplementation
(in terms of chaining waiting threads, with the linked
list stored in per-thread structure?).
os2.c
has a couple of static variables used in OS/2-specific
functions. (Need to be moved to per-thread structure,
or serialized?)
Note that these problems should not discourage experiment
ing, since they have a low probability of affecting small
programs.
AUTHOR
Ilya Zakharevich, ilya@math.ohio-state.edu
SEE ALSOperl(1).
2001-03-03 perl v5.6.1 PERLOS2(1)
