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[perl5.git] / README.os2

If you read this file _as_is_, just ignore the funny characters you
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=head1 NAME

perlos2 - Perl under OS/2, DOS, Win0.3*, Win0.95 and WinNT.

=head1 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 I<as is>: either as F<README.os2>, or F<pod/perlos2.pod>.

To read the F<.INF> version of documentation (B<very> recommended)
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 F<?:\JUST_ADD\view.exe>. This gives one an access to EMX's 
F<.INF> docs as well (text form is available in F</emx/doc> in 
EMX's distribution).

Note that if you have F<lynx.exe> installed, you can follow WWW links
from this document in F<.INF> format. If you have EMX docs installed 
correctly, you can follow library links (you need to have C<view emxbook>
working by setting C<EMXBOOK> environment variable as it is described
in EMX docs).

=cut

Contents
 
 perlos2 - Perl under OS/2, DOS, Win0.3*, Win0.95 and WinNT. 

      NAME 
      SYNOPSIS 
      DESCRIPTION 
         -  Target 
         -  Other OSes 
         -  Prerequisites 
         -  Starting Perl programs under OS/2 (and DOS and...)
         -  Starting OS/2 (and DOS) programs under Perl 
      Frequently asked questions 
         -  I cannot run external programs 
         -  I cannot embed perl into my program, or use perl.dll from my program. 
         -  `` and pipe-open do not work under DOS. 
         -  Cannot start find.exe "pattern" file
      INSTALLATION 
         -  Automatic binary installation 
         -  Manual binary installation 
         -  Warning 
      Accessing documentation 
         -  OS/2 .INF file 
         -  Plain text 
         -  Manpages 
         -  HTML 
         -  GNU info files 
         -  .PDF files 
         -  LaTeX docs 
      BUILD 
         -  Prerequisites 
         -  Getting perl source 
         -  Application of the patches 
         -  Hand-editing 
         -  Making 
         -  Testing 
         -  Installing the built perl 
         -  a.out-style build 
      Build FAQ 
         -  Some / became \ in pdksh. 
         -  'errno' - unresolved external 
         -  Problems with tr 
         -  Some problem (forget which ;-) 
         -  Library ... not found 
         -  Segfault in make 
      Specific (mis)features of EMX port 
         -  setpriority, getpriority 
         -  system() 
         -  extproc on the first line
         -  Additional modules: 
         -  Prebuilt methods: 
         -  Misfeatures 
         -  Modifications 
      Perl flavors 
         -  perl.exe 
         -  perl_.exe 
         -  perl__.exe 
         -  perl___.exe 
         -  Why strange names? 
         -  Why dynamic linking? 
         -  Why chimera build? 
      ENVIRONMENT 
         -  PERLLIB_PREFIX 
         -  PERL_BADLANG 
         -  PERL_BADFREE 
         -  PERL_SH_DIR 
         -  TMP or TEMP 
      Evolution 
         -  Priorities 
         -  DLL name mangling 
         -  Threading 
         -  Calls to external programs 
         -  Memory allocation 
         -  Threads
      AUTHOR 
      SEE ALSO 
  
=head1 DESCRIPTION

=head2 Target

The target is to make OS/2 the best supported platform for
using/building/developing Perl and I<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 B<too> hard).

The current state is quite close to this target. Known limitations:

=over 5

=item *

Some *nix programs use fork() a lot, but currently fork() is not
supported after I<use>ing dynamically loaded extensions.

=item *

You need a separate perl executable F<perl__.exe> (see L<perl__.exe>)
to use PM code in your application (like the forthcoming Perl/Tk).

=item *

There is no simple way to access WPS objects. The only way I know
is via C<OS2::REXX> extension (see L<OS2::REXX>), and we do not have access to
convenience methods of Object-REXX. (Is it possible at all? I know
of no Object-REXX API.)

=back

Please keep this list up-to-date by informing me about other items.

=head2 Other OSes

Since OS/2 port of perl uses a remarkable EMX environment, it can
run (and build extensions, and - possibly - be build 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 L<"perl_.exe">.

Note that not all features of Perl are available under these
environments. This depends on the features the I<extender> - most
probably RSX - decided to implement.

Cf. L<Prerequisites>.

=head2 Prerequisites

=over 6

=item EMX

EMX runtime is required (may be substituted by RSX). Note that
it is possible to make F<perl_.exe> to run under DOS without any
external support by binding F<emx.exe>/F<rsx.exe> to it, see L<emxbind>. Note
that under DOS for best results one should use RSX runtime, which
has much more functions working (like C<fork>, C<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 C<0.9c>. Perl may run
under earlier versions of EMX, but this is not tested.

One can get different parts of EMX from, say

  ftp://ftp.cdrom.com/pub/os2/emx09c/
  ftp://hobbes.nmsu.edu/os2/unix/emx09c/

The runtime component should have the name F<emxrt.zip>.

B<NOTE>. It is enough to have F<emx.exe>/F<rsx.exe> on your path. One
does not need to specify them explicitly (though this

  emx perl_.exe -de 0

will work as well.)

=item 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 
L<"Other OSes">). RSX would not work with VCPI
only, as EMX would, it requires DMPI.

Having RSX and the latest F<sh.exe> one gets a fully functional
B<*nix>-ish environment under DOS, say, C<fork>, C<``> and
pipe-C<open> work. In fact, MakeMaker 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 C<rainer@mathematik.uni-bielefeld.de>.

The latest F<sh.exe> with DOS hooks is available at

  ftp://ftp.math.ohio-state.edu/pub/users/ilya/os2/sh_dos.zip

=item 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.

=item 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<F:/bin>),
or in configurable location (see L<"PERL_SH_DIR">).

For best results use EMX pdksh. The soon-to-be-available standard
binary (5.2.12?) runs under DOS (with L<RSX>) as well, meanwhile use
the binary from

  ftp://ftp.math.ohio-state.edu/pub/users/ilya/os2/sh_dos.zip

=back

=head2 Starting Perl programs under OS/2 (and DOS and...)

Start your Perl program F<foo.pl> with arguments C<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 C<-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 F<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 C<extproc>, thus you are forced to
use C<-S> perl switch, and your script should be on 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 C<-my_opts> is taken care of by the C<extproc> line
in your script, see L<C<extproc> on the first line>).

To understand what the above I<magic> does, read perl docs about C<-S>
switch - see L<perlrun>, and cmdref about C<extproc>:

	view perl perlrun
	man perlrun
	view cmdref extproc
	help extproc

or whatever method you prefer.

There are also endless possibilities to use I<executable extensions> of
4os2, I<associations> of WPS and so on... However, if you use
*nixish shell (like F<sh.exe> supplied in the binary distribution),
you need to follow the syntax specified in L<perlrun/"Switches">.

Note that B<-S> switch enables a search with additional extensions 
F<.cmd>, F<.btm>, F<.bat>, F<.pl> as well.

=head2 Starting OS/2 (and DOS) programs under Perl

This is what system() (see L<perlfunc/system>), C<``> (see
L<perlop/"I/O Operators">), and I<open pipe> (see L<perlfunc/open>)
are for. (Avoid exec() (see L<perlfunc/exec>) 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 L<"Pdksh">, 
L<"Frequently asked questions">), and perl should be able to find it
(see L<"PERL_SH_DIR">).

The cases when the shell is used are:

=over

=item 1

One-argument system() (see L<perlfunc/system>), exec() (see L<perlfunc/exec>)
with redirection or shell meta-characters;

=item 2

Pipe-open (see L<perlfunc/open>) with the command which contains redirection 
or shell meta-characters;

=item 3

Backticks C<``> (see L<perlop/"I/O Operators">) with the command which contains
redirection or shell meta-characters;

=item 4

If the executable called by system()/exec()/pipe-open()/C<``> is a script
with the "magic" C<#!> line or C<extproc> line which specifies shell;

=item 5

If the executable called by system()/exec()/pipe-open()/C<``> is a script
without "magic" line, and C<$ENV{EXECSHELL}> is set to shell;

=item 6

If the executable called by system()/exec()/pipe-open()/C<``> is not
found;

=item 7

For globbing (see L<perlfunc/glob>, L<perlop/"I/O Operators">).

=back

For the sake of speed for a common case, in the above algorithms 
backslashes in the command name are not considered as shell metacharacters.

Perl starts scripts which begin with cookies
C<extproc> or C<#!> directly, without an intervention of shell.  Perl uses the
same algorithm to find the executable as F<pdksh>: if the path
on C<#!> line does not work, and contains C</>, then the executable
is searched in F<.> and on C<PATH>.  To find arguments for these scripts
Perl uses a different algorithm than F<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 F<sh.exe>, Perl uses
the same algorithm as F<pdksh>: if C<$ENV{EXECSHELL}> is set, the
script is given as the first argument to this command, if not set, then
C<$ENV{COMSPEC} /c> is used (or a hardwired guess if C<$ENV{COMSPEC}> is
not set).

If starting scripts directly, Perl will use exactly the same algorithm as for 
the search of script given by B<-S> command-line option: it will look in
the current directory, then on components of C<$ENV{PATH}> using the 
following order of appended extensions: no extension, F<.cmd>, F<.btm>, 
F<.bat>, F<.pl>.

Note that Perl will start to look for scripts only if OS/2 cannot start the
specified application, thus C<system 'blah'> will not look for a script if 
there is an executable file F<blah.exe> I<anywhere> on C<PATH>.  

Note also that executable files on OS/2 can have an arbitrary extension, 
but F<.exe> will be automatically appended if no dot is present in the name.  
The workaround as as simple as that:  since F<blah.> and F<blah> denote the 
same file, to start an executable residing in file F<n:/bin/blah> (no 
extension) give an argument C<n:/bin/blah.> to system().

The last note is that currently it is not straightforward to start PM 
programs from VIO (=text-mode) Perl process and visa versa.  Either ensure
that shell will be used, as in C<system 'cmd /c epm'>, or start it using
optional arguments to system() documented in C<OS2::Process> module.  This
is considered a bug and should be fixed soon.


=head1 Frequently asked questions

=head2 I cannot run external programs

=over 4

=item

Did you run your programs with C<-w> switch? See 
L<Starting OS/2 (and DOS) programs under Perl>.

=item

Do you try to run I<internal> shell commands, like C<`copy a b`>
(internal for F<cmd.exe>), or C<`glob a*b`> (internal for ksh)? You
need to specify your shell explicitly, like C<`cmd /c copy a b`>,
since Perl cannot deduce which commands are internal to your shell.

=back

=head2 I cannot embed perl into my program, or use F<perl.dll> from my
program. 

=over 4

=item Is your program EMX-compiled with C<-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.

=item Did you use L<ExtUtils::Embed>?

I had reports it does not work. Somebody would need to fix it.

=back

=head2 C<``> and pipe-C<open> do not work under DOS.

This may a variant of just L<"I cannot run external programs">, or a
deeper problem. Basically: you I<need> RSX (see L<"Prerequisites">)
for these commands to work, and you may need a port of F<sh.exe> which
understands command arguments. One of such ports is listed in
L<"Prerequisites"> under RSX. Do not forget to set variable
C<L<"PERL_SH_DIR">> as well.

DPMI is required for RSX.

=head2 Cannot start C<find.exe "pattern" file>

Use one of

  system 'cmd', '/c', 'find "pattern" file';
  `cmd /c 'find "pattern" file'`

This would start F<find.exe> via F<cmd.exe> via C<sh.exe> via
C<perl.exe>, but this is a price to pay if you want to use
non-conforming program. In fact F<find.exe> cannot be started at all
using C library API only. Otherwise the following command-lines were
equivalent:

  find "pattern" file
  find pattern file

=head1 INSTALLATION

=head2 Automatic binary installation

The most convenient way of installing perl is via perl installer
F<install.exe>. Just follow the instructions, and 99% of the
installation blues would go away. 

Note however, that you need to have F<unzip.exe> on your path, and
EMX environment I<running>. The latter means that if you just
installed EMX, and made all the needed changes to F<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.

B<Things not taken care of by automatic binary installation:>

=over 15

=item C<PERL_BADLANG>

may be needed if you change your codepage I<after> perl installation,
and the new value is not supported by EMX. See L<"PERL_BADLANG">.

=item C<PERL_BADFREE>

see L<"PERL_BADFREE">.

=item F<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 I<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.

=back

B<NOTE>. Because of a typo the binary installer of 5.00305
would install a variable C<PERL_SHPATH> into F<Config.sys>. Please
remove this variable and put C<L<PERL_SH_DIR>> instead.

=head2 Manual binary installation

As of version 5.00305, OS/2 perl binary distribution comes split
into 11 components. Unfortunately, to enable configurable 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 C<-d> to pkunzip). However, you
need to know where to extract the files. You need also to manually
change entries in F<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 C<(w)unzip>.

Below is the sample of what to do to reproduce the configuration on my
machine:

=over 3

=item 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 C<*.exe> on PATH, and C<*.dll> on
LIBPATH);

=item Perl_ VIO executable (statically linked)

  unzip perl_aou.zip -d f:/emx.add/bin

(have the directory on PATH);

=item Executables for Perl utilities

  unzip perl_utl.zip -d f:/emx.add/bin

(have the directory on PATH);

=item Main Perl library

  unzip perl_mlb.zip -d f:/perllib/lib

If this directory is preserved, you do not need to change
anything. However, for perl to find it if it is changed, you need to
C<set PERLLIB_PREFIX> in F<Config.sys>, see L<"PERLLIB_PREFIX">.

=item Additional Perl modules

  unzip perl_ste.zip -d f:/perllib/lib/site_perl

If you do not change this directory, do nothing. Otherwise put this
directory and subdirectory F<./os2> in C<PERLLIB> or C<PERL5LIB>
variable. Do not use C<PERL5LIB> unless you have it set already. See
L<perl/"ENVIRONMENT">. 

=item Tools to compile Perl modules

  unzip perl_blb.zip -d f:/perllib/lib

If this directory is preserved, you do not need to change
anything. However, for perl to find it if it is changed, you need to
C<set PERLLIB_PREFIX> in F<Config.sys>, see L<"PERLLIB_PREFIX">.

=item Manpages for Perl and utilities

  unzip perl_man.zip -d f:/perllib/man

This directory should better be on C<MANPATH>. You need to have a
working man to access these files.

=item Manpages for Perl modules

  unzip perl_mam.zip -d f:/perllib/man

This directory should better be on C<MANPATH>. You need to have a
working man to access these files.

=item Source for Perl documentation

  unzip perl_pod.zip -d f:/perllib/lib

This is used by by C<perldoc> program (see L<perldoc>), and may be used to
generate HTML documentation usable by WWW browsers, and
documentation in zillions of other formats: C<info>, C<LaTeX>,
C<Acrobat>, C<FrameMaker> and so on.

=item Perl manual in F<.INF> format

  unzip perl_inf.zip -d d:/os2/book

This directory should better be on C<BOOKSHELF>.

=item 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 I<redirection> and I<shell
metacharacters>. It is also used instead of explicit F</bin/sh>.

Set C<PERL_SH_DIR> (see L<"PERL_SH_DIR">) if you move F<sh.exe> from
the above location.

B<Note.> It may be possible to use some other sh-compatible shell
(I<not tested>).

=back

After you installed the components you needed and updated the
F<Config.sys> correspondingly, you need to hand-edit
F<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'}"

You need to correct all the entries which look like file paths (they
currently start with C<f:/>).

=head2 B<Warning>

The automatic and manual perl installation leave precompiled paths
inside perl executables. While these paths are overwriteable (see
L<"PERLLIB_PREFIX">, L<"PERL_SH_DIR">), one may get better results by
binary editing of paths inside the executables/DLLs.

=head1 Accessing documentation

Depending on how you built/installed perl you may have (otherwise
identical) Perl documentation in the following formats:

=head2 OS/2 F<.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 L<"SYNOPSIS">.

If you want to build the docs yourself, and have I<OS/2 toolkit>, run

	pod2ipf > perl.ipf

in F</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.

=head2 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 F<.pod> files.

=head2 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 (F<.>) is used as a package separator for documentation
for packages, and as usual, sometimes you need to give the section - C<3>
above - to avoid shadowing by the I<less(1) manpage>.

Make sure that the directory B<above> the directory with manpages is
on our C<MANPATH>, like this

  set MANPATH=c:/man;f:/perllib/man

=head2 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 F<.pod> files, and do like this

	cd f:/perllib/lib/pod
	pod2html

After this you can direct your browser the file F<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.

=head2 GNU C<info> files

Users of Emacs would appreciate it very much, especially with
C<CPerl> mode loaded. You need to get latest C<pod2info> from C<CPAN>,
or, alternately, prebuilt info pages.

=head2 F<.PDF> files

for C<Acrobat> are available on CPAN (for slightly old version of
perl).

=head2 C<LaTeX> docs

can be constructed using C<pod2latex>.

=head1 BUILD

Here we discuss how to build Perl under OS/2. There is an alternative
(but maybe older) view on L<http://www.shadow.net/~troc/os2perl.html>.

=head2 Prerequisites

You need to have the latest EMX development environment, the full
GNU tool suite (gawk renamed to awk, and GNU F<find.exe>
earlier on path than the OS/2 F<find.exe>, same with F<sort.exe>, to
check use

  find --version
  sort --version

). You need the latest version of F<pdksh> installed as F<sh.exe>.

Check that you have B<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, gnututil.zip, gnused.zip,
gnupatch.zip, gnuawk.zip, gnumake.zip and ksh527rt.zip.  Note that
all these utilities are known to be available from LEO:

  ftp://ftp.leo.org/pub/comp/os/os2/leo/gnu

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 F</tmp> directory on the current drive,
and F<.> directory in your C<LIBPATH>. One may try to correct the
latter condition by

  set BEGINLIBPATH .

if you use something like F<CMD.EXE> or latest versions of F<4os2.exe>.

Make sure your gcc is good for C<-Zomf> linking: run C<omflibs>
script in F</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 I<Selective install>, and choose C<Link
object modules> in I<Optional system utilities/More>. If you get into
link386, press C<Ctrl-C>.

=head2 Getting perl source

You need to fetch the latest perl source (including developers
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 F<Configure>. This is
because there is a conflict with a similarly-named file F<configure>.

Change to the directory of extraction.

=head2 Application of the patches

You need to apply the patches in F<./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 F<db.lib> and F<db.a> from the EMX distribution
are not suitable for multi-threaded compile (note that currently perl
is not multithread-safe, but is compiled as multithreaded for
compatibility with XFree86-OS/2). Get a corrected one from

  ftp://ftp.math.ohio-state.edu/pub/users/ilya/os2/db_mt.zip

To make C<-p> filetest work, one may also need to apply the following patch
to EMX headers:

  --- /emx/include/sys/stat.h.orig	Thu May 23 13:48:16 1996
  +++ /emx/include/sys/stat.h	Sun Jul 12 14:11:32 1998
  @@ -53,7 +53,7 @@ struct stat
   #endif

   #if !defined (S_IFMT)
  -#define S_IFMT   0160000  /* Mask for file type */
  +#define S_IFMT   0170000  /* Mask for file type */
   #define S_IFIFO  0010000  /* Pipe */
   #define S_IFCHR  0020000  /* Character device */
   #define S_IFDIR  0040000  /* Directory */


=head2 Hand-editing

You may look into the file F<./hints/os2.sh> and correct anything
wrong you find there. I do not expect it is needed anywhere.

=head2 Making

  sh Configure -des -D prefix=f:/perllib

C<prefix> means: where to install the resulting perl library. Giving
correct prefix you may avoid the need to specify C<PERLLIB_PREFIX>,
see L<"PERLLIB_PREFIX">.

I<Ignore the message about missing C<ln>, and about C<-c> option to
tr>. In fact if you can trace where the latter spurious warning
comes from, please inform me.

Now

  make

At some moment the built may die, reporting a I<version mismatch> or
I<unable to run F<perl>>. This means that most of the build has been
finished, and it is the time to move the constructed F<perl.dll> to
some I<absolute> location in LIBPATH. After this is done the build
should finish without a lot of fuss. I<One can avoid the interruption
if one has the correct prebuilt version of F<perl.dll> on LIBPATH, but
probably this is not needed anymore, since F<miniperl.exe> is linked
statically now.>

Warnings which are safe to ignore: I<mkfifo() redefined> inside
F<POSIX.c>.

=head2 Testing

If you haven't yet moved perl.dll onto LIBPATH, do it now (alternatively, if
you have a previous perl installation you'd rather not disrupt until this one
is installed, copy perl.dll to the t directory).

Now run

  make test

All tests should succeed (with some of them skipped).  Note that on one
of the systems I see intermittent failures of F<io/pipe.t> subtest 9.
Any help to track what happens with this test is appreciated.

Some tests may generate extra messages similar to

=over 4

=item A lot of C<bad free>

in database tests related to Berkeley DB. This is a confirmed bug of
DB. You may disable this warnings, see L<"PERL_BADFREE">.

There is not much we can do with it (but apparently it does not cause 
any real error with data).

=item Process terminated by SIGTERM/SIGINT

This is a standard message issued by OS/2 applications. *nix
applications die in silence. It is considered 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 I<should> be present during
testing.

=back

Two F<lib/io_*> tests may generate popups (system error C<SYS3175>), 
but should succeed anyway.  This is due to a bug of EMX related to 
fork()ing with dynamically loaded libraries.

I submitted a patch to EMX which makes it possible to fork() with EMX 
dynamic libraries loaded, which makes F<lib/io*> tests pass without
skipping offended tests. This means that soon the number of skipped tests
may decrease yet more.

To get finer test reports, call

  perl t/harness

The report with F<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:

=over 8

=item F<op/fs.t>

=over 4

=item 18

Checks C<atime> and C<mtime> of C<stat()> - unfortunately, HPFS
provides only 2sec time granularity (for compatibility with FAT?).

=item 25

Checks C<truncate()> on a filehandle just opened for write - I do not
know why this should or should not work.

=back

=item F<lib/io_pipe.t>

Checks C<IO::Pipe> module. Some feature of EMX - test fork()s with
dynamic extension loaded - unsupported now.

=item F<lib/io_sock.t>

Checks C<IO::Socket> module. Some feature of EMX - test fork()s
with dynamic extension loaded - unsupported now.

=item F<op/stat.t>

Checks C<stat()>. Tests:

=over 4

=item 4

Checks C<atime> and C<mtime> of C<stat()> - unfortunately, HPFS
provides only 2sec time granularity (for compatibility with FAT?).

=back

=item F<lib/io_udp.t>

It never terminates, apparently some bug in storing the last socket from
which we obtained a message.

=back

=head2 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
F<perl.exe>, F<perl__.exe> and F<perl___.exe> to a location on your
PATH, F<perl.dll> to a location on your LIBPATH.

Run

  make cmdscripts INSTALLCMDDIR=d:/ir/on/path

to convert perl utilities to F<.cmd> files and put them on
PATH. You need to put F<.EXE>-utilities on path manually. They are
installed in C<$prefix/bin>, here C<$prefix> is what you gave to
F<Configure>, see L<Making>.

=head2 C<a.out>-style build

Proceed as above, but make F<perl_.exe> (see L<"perl_.exe">) by

  make perl_

test and install by

  make aout_test
  make aout_install

Manually put F<perl_.exe> to a location on your PATH.

Since C<perl_> has the extensions prebuilt, it does not suffer from
the I<dynamic extensions + fork()> syndrome, thus the failing tests
look like

  Failed Test  Status Wstat Total Fail  Failed  List of failed
  ---------------------------------------------------------------
  io/fs.t                      26   11  42.31%  2-5, 7-11, 18, 25
  op/stat.t                    56    5   8.93%  3-4, 20, 35, 39
  Failed 2/118 test scripts, 98.31% okay. 16/2445 subtests failed, 99.35% okay.

B<Note.> The build process for C<perl_> I<does not know> about all the
dependencies, so you should make sure that anything is up-to-date,
say, by doing

  make perl.dll

first.

=head1 Build FAQ

=head2 Some C</> became C<\> in pdksh.

You have a very old pdksh. See L<Prerequisites>.

=head2 C<'errno'> - unresolved external

You do not have MT-safe F<db.lib>. See L<Prerequisites>.

=head2 Problems with tr or sed

reported with very old version of tr and sed.

=head2 Some problem (forget which ;-)

You have an older version of F<perl.dll> on your LIBPATH, which
broke the build of extensions.

=head2 Library ... not found

You did not run C<omflibs>. See L<Prerequisites>.

=head2 Segfault in make

You use an old version of GNU make. See L<Prerequisites>.

=head1 Specific (mis)features of OS/2 port

=head2 C<setpriority>, C<getpriority>

Note that these functions are compatible with *nix, not with the older
ports of '94 - 95. The priorities are absolute, go from 32 to -95,
lower is quicker. 0 is the default priority.

=head2 C<system()>

Multi-argument form of C<system()> allows an additional numeric
argument. The meaning of this argument is described in
L<OS2::Process>.

=head2 C<extproc> on the first line

If the first chars of a script are C<"extproc ">, this line is treated
as C<#!>-line, thus all the switches on this line are processed (twice
if script was started via cmd.exe).

=head2 Additional modules:

L<OS2::Process>, L<OS2::REXX>, L<OS2::PrfDB>, L<OS2::ExtAttr>. These
modules provide access to additional numeric argument for C<system>
and to the list of the running processes,
to DLLs having functions with REXX signature and to REXX runtime, to
OS/2 databases in the F<.INI> format, and to Extended Attributes.

Two additional extensions by Andreas Kaiser, C<OS2::UPM>, and
C<OS2::FTP>, are included into my ftp directory, mirrored on CPAN.

=head2 Prebuilt methods:

=over 4

=item C<File::Copy::syscopy>

used by C<File::Copy::copy>, see L<File::Copy>.

=item C<DynaLoader::mod2fname>

used by C<DynaLoader> for DLL name mangling.

=item  C<Cwd::current_drive()>

Self explanatory.

=item  C<Cwd::sys_chdir(name)>

leaves drive as it is.

=item  C<Cwd::change_drive(name)>


=item  C<Cwd::sys_is_absolute(name)>

means has drive letter and is_rooted.

=item  C<Cwd::sys_is_rooted(name)>

means has leading C<[/\\]> (maybe after a drive-letter:).

=item  C<Cwd::sys_is_relative(name)>

means changes with current dir.

=item  C<Cwd::sys_cwd(name)>

Interface to cwd from EMX. Used by C<Cwd::cwd>.

=item  C<Cwd::sys_abspath(name, dir)>

Really really odious function to implement. Returns absolute name of
file which would have C<name> if CWD were C<dir>.  C<Dir> defaults to the
current dir.

=item  C<Cwd::extLibpath([type])>

Get current value of extended library search path. If C<type> is
present and I<true>, works with END_LIBPATH, otherwise with
C<BEGIN_LIBPATH>. 

=item  C<Cwd::extLibpath_set( path [, type ] )>

Set current value of extended library search path. If C<type> is
present and I<true>, works with END_LIBPATH, otherwise with
C<BEGIN_LIBPATH>. 

=back

(Note that some of these may be moved to different libraries -
eventually).


=head2 Misfeatures

=over 4

=item

Since L<flock(3)> is present in EMX, but is not functional, it is 
emulated by perl.  To disable the emulations, set environment variable
C<USE_PERL_FLOCK=0>.

=item

Here is the list of things which may be "broken" on
EMX (from EMX docs):

=over

=item *

The functions L<recvmsg(3)>, L<sendmsg(3)>, and L<socketpair(3)> are not
implemented.

=item *

L<sock_init(3)> is not required and not implemented.

=item *

L<flock(3)> is not yet implemented (dummy function).  (Perl has a workaround.)

=item *

L<kill(3)>:  Special treatment of PID=0, PID=1 and PID=-1 is not implemented.

=item *

L<waitpid(3)>:

      WUNTRACED
	      Not implemented.
      waitpid() is not implemented for negative values of PID.

=back

Note that C<kill -9> does not work with the current version of EMX.

=item

Since F<sh.exe> is used for globing (see L<perlfunc/glob>), the bugs
of F<sh.exe> plague perl as well. 

In particular, uppercase letters do not work in C<[...]>-patterns with
the current pdksh.

=back

=head2 Modifications

Perl modifies some standard C library calls in the following ways:

=over 9

=item C<popen>

C<my_popen> uses F<sh.exe> if shell is required, cf. L<"PERL_SH_DIR">.

=item C<tmpnam>

is created using C<TMP> or C<TEMP> environment variable, via
C<tempnam>.

=item C<tmpfile>

If the current directory is not writable, file is created using modified
C<tmpnam>, so there may be a race condition.

=item C<ctermid>

a dummy implementation.

=item C<stat>

C<os2_stat> special-cases F</dev/tty> and F</dev/con>.

=item C<flock>

Since L<flock(3)> is present in EMX, but is not functional, it is 
emulated by perl.  To disable the emulations, set environment variable
C<USE_PERL_FLOCK=0>.

=back

=head1 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:

=head2 F<perl.exe>

The main workhorse. This is a chimera executable: it is compiled as an
C<a.out>-style executable, but is linked with C<omf>-style dynamic
library F<perl.dll>, and with dynamic CRT DLL. This executable is a
VIO application.

It can load perl dynamic extensions, and it can fork(). Unfortunately,
with the current version of EMX it cannot fork() with dynamic
extensions loaded (may be fixed by patches to EMX).

B<Note.> Keep in mind that fork() is needed to open a pipe to yourself.

=head2 F<perl_.exe>

This is a statically linked C<a.out>-style executable. It can fork(),
but cannot load dynamic Perl extensions. The supplied executable has a
lot of extensions prebuilt, thus there are situations when it can
perform tasks not possible using F<perl.exe>, like fork()ing when
having some standard extension loaded. This executable is a VIO
application.

B<Note.> A better behaviour could be obtained from C<perl.exe> if it
were statically linked with standard I<Perl extensions>, but
dynamically linked with the I<Perl DLL> and CRT DLL. Then it would
be able to fork() with standard extensions, I<and> would be able to
dynamically load arbitrary extensions. Some changes to Makefiles and
hint files should be necessary to achieve this.

I<This is also the only executable with does not require OS/2.> The
friends locked into C<M$> world would appreciate the fact that this
executable runs under DOS, Win0.3*, Win0.95 and WinNT with an
appropriate extender. See L<"Other OSes">.

=head2 F<perl__.exe>

This is the same executable as F<perl___.exe>, but it is a PM
application. 

B<Note.> Usually STDIN, STDERR, and STDOUT of a PM
application are redirected to C<nul>. However, it is possible to see
them if you start C<perl__.exe> from a PM program which emulates a
console window, like I<Shell mode> of Emacs or EPM. Thus it I<is
possible> to use Perl debugger (see L<perldebug>) to debug your PM
application.

This flavor is required if you load extensions which use PM, like
the forthcoming C<Perl/Tk>.

=head2 F<perl___.exe>

This is an C<omf>-style executable which is dynamically linked to
F<perl.dll> and CRT DLL. I know no advantages of this executable
over C<perl.exe>, but it cannot fork() at all. Well, one advantage is
that the build process is not so convoluted as with C<perl.exe>.

It is a VIO application.

=head2 Why strange names?

Since Perl processes the C<#!>-line (cf. 
L<perlrun/DESCRIPTION>, L<perlrun/Switches>,
L<perldiag/"Not a perl script">, 
L<perldiag/"No Perl script found in input">), it should know when a
program I<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).

=head2 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 stupid-but-quick
"hard" dynamic linking used by OS/2.

The address tables of DLLs are patched only once, when they are
loaded. The addresses of entry points into DLLs are guaranteed to be
the same for all programs which use the same DLL, which reduces the
amount of runtime patching - once DLL is loaded, its code is
read-only.

While this allows some performance advantages, this makes life
terrible for developers, since the above scheme makes it impossible
for a DLL to be resolved to a symbol in the .EXE file, since this
would need a DLL to have different relocations tables for the
executables which use it.

However, a Perl extension is forced to use some symbols from the perl
executable, say to know how to find the arguments provided on the perl
internal evaluation stack. The solution is that the main code of
interpreter should be contained in a DLL, and the F<.EXE> file just loads
this DLL into memory and supplies command-arguments.

This I<greatly> increases the load time for the application (as well as
the number of problems during compilation). Since interpreter is in a DLL,
the CRT is basically forced to reside in a DLL as well (otherwise
extensions would not be able to use CRT).

=head2 Why chimera build?

Current EMX environment does not allow DLLs compiled using Unixish
C<a.out> format to export symbols for data. This forces C<omf>-style
compile of F<perl.dll>.

Current EMX environment does not allow F<.EXE> files compiled in
C<omf> format to fork(). fork() is needed for exactly three Perl
operations:

=over 4

=item explicit fork()

in the script, and

=item open FH, "|-"

=item open FH, "-|"

opening pipes to itself.

=back

While these operations are not questions of life and death, a lot of
useful scripts use them. This forces C<a.out>-style compile of
F<perl.exe>.


=head1 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.

=head2 C<PERLLIB_PREFIX>

Specific for EMX port. Should have the form

  path1;path2

or

  path1 path2

If the beginning of some prebuilt path matches F<path1>, it is
substituted with F<path2>.

Should be used if the perl library is moved from the default
location in preference to C<PERL(5)LIB>, since this would not leave wrong
entries in @INC.  Say, if the compiled version of perl looks for @INC
in F<f:/perllib/lib>, and you want to install the library in
F<h:/opt/gnu>, do

  set PERLLIB_PREFIX=f:/perllib/lib;h:/opt/gnu

=head2 C<PERL_BADLANG>

If 1, perl ignores setlocale() failing. May be useful with some
strange I<locale>s.

=head2 C<PERL_BADFREE>

If 1, perl would not warn of in case of unwarranted free(). May be
useful in conjunction with the module DB_File, since Berkeley DB
memory handling code is buggy.

=head2 C<PERL_SH_DIR>

Specific for EMX port. Gives the directory part of the location for
F<sh.exe>.

=head2 C<USE_PERL_FLOCK>

Specific for EMX port. Since L<flock(3)> is present in EMX, but is not 
functional, it is emulated by perl.  To disable the emulations, set 
environment variable C<USE_PERL_FLOCK=0>.

=head2 C<TMP> or C<TEMP>

Specific for EMX port. Used as storage place for temporary files, most
notably C<-e> scripts.

=head1 Evolution

Here we list major changes which could make you by surprise.

=head2 Priorities

C<setpriority> and C<getpriority> are not compatible with earlier
ports by Andreas Kaiser. See C<"setpriority, getpriority">.

=head2 DLL name mangling

With the release 5.003_01 the dynamically loadable libraries
should be rebuilt. In particular, DLLs are now created with the names
which contain a checksum, thus allowing workaround for OS/2 scheme of
caching DLLs.

=head2 Threading

As of release 5.003_01 perl is linked to multithreaded CRT
DLL.  If perl itself is not compiled multithread-enabled, so will not be perl
malloc(). However, extensions may use multiple thread on their own
risk. 

Needed to compile C<Perl/Tk> for XFree86-OS/2 out-of-the-box.

=head2 Calls to external programs

Due to a popular demand the perl external program calling has been
changed wrt Andreas Kaiser's port.  I<If> perl needs to call an
external program I<via shell>, the F<f:/bin/sh.exe> will be called, or
whatever is the override, see L<"PERL_SH_DIR">.

Thus means that you need to get some copy of a F<sh.exe> as well (I
use one from pdksh). The drive F<F:> above is set up automatically during
the build to a correct value on the builder machine, but is
overridable at runtime,

B<Reasons:> a consensus on C<perl5-porters> was that perl should use
one non-overridable shell per platform. The obvious choices for OS/2
are F<cmd.exe> and F<sh.exe>. Having perl build itself would be impossible
with F<cmd.exe> as a shell, thus I picked up C<sh.exe>. Thus 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 L<"Prerequisites">).

B<Disadvantages:> currently F<sh.exe> of pdksh calls external programs
via fork()/exec(), and there is I<no> functioning exec() on
OS/2. exec() is emulated by EMX by asyncroneous call while the caller
waits for child completion (to pretend that the C<pid> did not change). This
means that 1 I<extra> copy of F<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 F<sh.exe>
unless needed (metachars found).

One can always start F<cmd.exe> explicitly via

  system 'cmd', '/c', 'mycmd', 'arg1', 'arg2', ...

If you need to use F<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(), C<``>, and
C<open(,'...|')>. With current perl you may override only system(),
readpipe() - the explicit version of C<``>, and maybe exec(). The code
will substitute the one-argument call to system() by
C<CORE::system('cmd.exe', '/c', shift)>.

If you have some working code for C<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 L<Starting OS/2 (and DOS) programs under Perl>.

=over

=item

External scripts may be called by name.  Perl will try the same extensions
as when processing B<-S> command-line switch.

=back

=head2 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 benchmarks show that Perl's malloc is 5 times quickier
than EMX one.  I do not have convincing data about memory footpring, but
a (pretty random) benchmark showed that Perl one is 5% better.

Combination of perl's malloc() and rigid DLL name resolution 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 C<emx_> added. (Currently only DLL perl has this, it should 
propagate to F<perl_.exe> shortly.)

=head2 Threads

One can build perl with thread support enabled by providing C<-D usethreads>
option to F<Configure>.  Currently OS/2 support of threads is very 
preliminary.

Most notable problems: 

=over

=item C<COND_WAIT> 

may have a race condition.  Needs a reimplementation (in terms of chaining
waiting threads, with linker list stored in per-thread structure?).

=item F<os2.c>

has a couple of static variables used in OS/2-specific functions.  (Need to be
moved to per-thread structure, or serialized?)

=back

Note that these problems should not discourage experimenting, since they
have a low probability of affecting small programs.

=cut

OS/2 extensions
~~~~~~~~~~~~~~~
I include 3 extensions by Andreas Kaiser, OS2::REXX, OS2::UPM, and OS2::FTP, 
into my ftp directory, mirrored on CPAN. I made
some minor changes needed to compile them by standard tools. I cannot 
test UPM and FTP, so I will appreciate your feedback. Other extensions
there are OS2::ExtAttr, OS2::PrfDB for tied access to EAs and .INI
files - and maybe some other extensions at the time you read it.

Note that OS2 perl defines 2 pseudo-extension functions
OS2::Copy::copy and DynaLoader::mod2fname (many more now, see
L<Prebuilt methods>).

The -R switch of older perl is deprecated. If you need to call a REXX code
which needs access to variables, include the call into a REXX compartment
created by 
	REXX_call {...block...};

Two new functions are supported by REXX code, 
	REXX_eval 'string';
	REXX_eval_with 'string', REXX_function_name => \&perl_sub_reference;

If you have some other extensions you want to share, send the code to
me.  At least two are available: tied access to EA's, and tied access
to system databases.

=head1 AUTHOR

Ilya Zakharevich, ilya@math.ohio-state.edu

=head1 SEE ALSO

perl(1).

=cut