If you read this file _as_is_, just ignore the funny characters you see. It is written in the POD format (see perlpod manpage) which is specially designed to be readable as is. =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: either as F, or F. To read the F<.INF> version of documentation (B 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. This gives one an access to B's F<.INF> docs as well (text form is available in F in B's distribution). =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 - Starting OS/2 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. 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 OS/2 port - setpriority, getpriority - system() - 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 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, as well as make Perl the best language to use under OS/2. 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 Iing dynamically loaded extensions. =item * You need a separate perl executable F (see L) to use PM code in your application (like the forthcoming Perl/Tk). =item * There is no simple way to access B objects. The only way I know is via C extension (see L), and we do not have access to convenience methods of B. (Is it possible at all? I know of no B 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 B 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 - most probably C - decided to implement. Cf. L. =head2 Prerequisites =over 6 =item B B runtime is required (may be substituted by B). Note that it is possible to make F to run under DOS without any external support by binding F/F to it, see L. Note that under DOS for best results one should use B runtime, which has much more functions working (like C, C and so on). In fact B is required if there is no C present. Note the B requires C. Only the latest runtime is supported, currently C<0.9c>. One can get different parts of B from, say ftp://ftp.cdrom.com/pub/os2/emx0.9c/ ftp://hobbes.nmsu.edu/os2/unix/gnu/ The runtime component should have the name F. B. It is enough to have F/F on your path. One does not need to specify them explicitly (though this emx perl_.exe -de 0 will work as well.) =item B To run Perl on C platforms one needs B runtime. This is needed under DOS-inside-OS/2, Win0.3*, Win0.95 and WinNT (see L<"Other OSes">). B would not work with C only, as B would, it requires C. Having B and the latest F one gets a fully functional B<*nix>-ish environment under DOS, say, C, C<``> and pipe-C work. In fact, MakeMaker works (for static build), so one can have Perl development environment under DOS. One can get B from, say ftp://ftp.cdrom.com/pub/os2/emx0.9c/contrib ftp://ftp.uni-bielefeld.de/pub/systems/msdos/misc Contact the author on C. The latest F with DOS hooks is available at ftp://ftp.math.ohio-state.edu/pub/users/ilya/os2/sh_dos.exe =item B 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 B to truncate file names. This is not supported, read B docs to see how to do it. =back =head2 Starting Perl programs under OS/2 Start your Perl program F with arguments C 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 C or C<4os2>, put the following at the start of your perl script: extproc perl -x -S #!/usr/bin/perl -my_opts rename your program to F, and start it by typing foo arg1 arg2 arg3 (Note that having *nixish full path to perl F is not necessary, F would be enough, but having full path would make it easier to use your script under *nix.) Note that because of stupid OS/2 limitations the full path of the perl script is not available when you use C, 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 -x ../../blah/foo.cmd arg1 arg2 arg3 (note that the argument C<-my_opts> is taken care of by the C<#!> line in your script). To understand what the above I does, read perl docs about C<-S> and C<-x> switches - see L, and cmdref about C: view perl perlrun man perlrun view cmdref extproc help extproc or whatever method you prefer. There are also endless possibilities to use I of B<4OS2>, I of B and so on... However, if you use *nixish shell (like F supplied in the binary distribution), you need to follow the syntax specified in L. =head2 Starting OS/2 programs under Perl This is what system() (see L), C<``> (see L), and I (see L) are for. (Avoid exec() (see L) unless you know what you do). Note however that to use some of these operators you need to have a C-syntax shell installed (see L<"Pdksh">, L<"Frequently asked questions">), and perl should be able to find it (see L<"PERL_SH_DIR">). The only cases when the shell is not used is the multi-argument system() (see L)/exec() (see L), and one-argument version thereof without redirection and shell meta-characters. =head1 Frequently asked questions =head2 I cannot run external programs =over 4 =item Did you run your programs with C<-w> switch? See L. =item Do you try to run I shell commands, like C<`copy a b`> (internal for F), 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 from my program. =over 4 =item Is your program B-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 C? I had reports it does not work. Somebody would need to fix it. =back =head2 C<``> and pipe-C do not work under DOS. This may a variant of just L<"I cannot run external programs">, or a deeper problem. Basically: you I B (see L<"Prerequisites">) for these commands to work, and you may need a port of F which understands command arguments. One of such ports is listed in L<"Prerequisites"> under B. C is required for B. =head1 INSTALLATION =head2 Automatic binary installation The most convenient way of installing perl is via perl installer F. Just follow the instructions, and 99% of the installation blues would go away. Note however, that you need to have F on your path, and B environment I. The latter means that if you just installed B, and made all the needed changes to F, you may need to reboot in between. Check B runtime by running emxrev A folder is created on your desktop which contains some useful objects. B =over 15 =item C may be needed if you change your codepage I perl installation, and the new value is not supported by B. See L<"PERL_BADLANG">. =item C see L<"PERL_BADFREE">. =item F 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 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 =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 C files are not absolute, but relative to some directory. Note that the extraction with the stored paths is still necessary (default with C, specify C<-d> to C). However, you need to know where to extract the files. You need also to manually change entries in F to reflect where did you put the files. Note that if you have some primitive unzipper (like C), 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 C, and C<*.dll> on C); =item Perl_ VIO executable (statically linked) unzip perl_aou.zip -d f:/emx.add/bin (have the directory on C); =item Executables for Perl utilities unzip perl_utl.zip -d f:/emx.add/bin (have the directory on C); =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 in F, 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 or C variable. Do not use C unless you have it set already. See L. =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 in F, 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. You need to have a working C to access these files. =item Manpages for Perl modules unzip perl_mam.zip -d f:/perllib/man This directory should better be on C. You need to have a working C to access these files. =item Source for Perl documentation unzip perl_pod.zip -d f:/perllib/lib This is used by by C program (see L), and may be used to generate B documentation usable by WWW browsers, and documentation in zillions of other formats: C, C, C, C and so on. =item Perl manual in .INF format unzip perl_inf.zip -d d:/os2/book This directory should better be on C. =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 and I. It is also used instead of explicit F. Set C (see L<"PERL_SH_DIR">) if you move F from the above location. B It may be possible to use some other C-compatible shell (I). =back After you installed the components you needed and updated the F correspondingly, you need to hand-edit F. 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). =head2 B 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. 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). If you want to build the docs yourself, and have I, run pod2ipf > perl.ipf in F 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 B C 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 C 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. Make sure that the directory B the directory with manpages is on our C, like this set MANPATH=c:/man;f:/perllib/man =head2 B If you have some WWW browser available, installed the Perl documentation in the source form, and Perl utilities, you can build B 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 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 C. =head2 B C files Users of C would appreciate it very much, especially with C mode loaded. You need to get latest C from C, or, alternately, prebuilt info pages. =head2 F<.PDF> files for C are available on CPAN (for slightly old version of perl). =head2 C docs can be constructed using C. =head1 BUILD Here we discuss how to build Perl under OS/2. There is an alternative (but maybe older) view on L. =head2 Prerequisites You need to have the latest B development environment, the full B tool suite (C renamed to C, and B F earlier on path than the OS/2 F, same with F, to check use find --version sort --version ). You need the latest version of F installed as F. Possible locations to get this from are ftp://hobbes.nmsu.edu/os2/unix/gnu/ ftp://ftp.cdrom.com/pub/os2/unix/ ftp://ftp.cdrom.com/pub/os2/dev32/ ftp://ftp.cdrom.com/pub/os2/emx0.9c/ 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 directory on the current drive, and F<.> directory in your C. One may try to correct the latter condition by set BEGINLIBPATH . if you use something like F or latest versions of F<4os2.exe>. Make sure your C is good for C<-Zomf> linking: run C script in F directory. Check that you have C 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, and choose C in I. If you get into C, press 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. This is because there is a conflict with a similarly-named file F. Rename F to F. Extract F like this tar --case-sensitive -vzxf perl5.00409.tar.gz perl5.00409/Configure Change to the directory of extraction. =head2 Application of the patches You need to apply the patches in F<./os2/diff.*> and F<./os2/POSIX.mkfifo> like this: gnupatch -p0 < os2\POSIX.mkfifo 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 and F from the B distribution are not suitable for multi-threaded compile (note that currently perl is not multithreaded, but is compiled as multithreaded for compatibility with B-OS/2). Get a corrected one from ftp://ftp.math.ohio-state.edu/pub/users/ilya/os2/db_mt.zip =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 Prefix means where to install the resulting perl library. Giving correct prefix you may avoid the need to specify C, see L<"PERLLIB_PREFIX">. I, and about C<-c> option to C>. 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 or I>. This means that most of the build has been finished, and it is the time to move the constructed F to some I location in C. After this done the build should finish without a lot of fuss. I on C.> Warnings which are safe to ignore: I inside F. =head2 Testing Now run make test Some tests (4..6) should fail. Some perl invocations should end in a segfault (system error C). To get finer error reports, cd t perl -I ../lib harness The report you get may 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 lib/io_pipe.t 3 768 6 ?? % ?? lib/io_sock.t 3 768 5 ?? % ?? op/stat.t 56 5 8.93% 3-4, 20, 35, 39 Failed 4/140 test scripts, 97.14% okay. 27/2937 subtests failed, 99.08% okay. Note that using `make test' target two more tests may fail: C because of (mis)feature of C, and C, which checks that the buffers are not flushed on C<_exit> (this is a bug in the test which assumes that tty output is buffered). I submitted a patch to B which makes it possible to fork() with EMX dynamic libraries loaded, which makes F tests pass. This means that soon the number of failing tests may decrease yet more. However, the test F is disabled, since it never terminates, I do not know why. Comments/fixes welcome. The reasons for failed tests are: =over 8 =item F Checks I operations. Tests: =over 10 =item 2-5, 7-11 Check C and C - nonesuch under OS/2. =item 18 Checks C and C of C - I could not understand this test. =item 25 Checks C on a filehandle just opened for write - I do not know why this should or should not work. =back =item F Checks C module. Some feature of B - test fork()s with dynamic extension loaded - unsupported now. =item F Checks C module. Some feature of B - test fork()s with dynamic extension loaded - unsupported now. =item F Checks C. Tests: =over 4 =item 3 Checks C - nonesuch under OS/2. =item 4 Checks C and C of C - I could not understand this test. =item 20 Checks C<-x> - determined by the file extension only under OS/2. =item 35 Needs F. =item 39 Checks C<-t> of F. Should not fail! =back =back In addition to errors, you should get a lot of warnings. =over 4 =item A lot of `bad free' in databases related to Berkeley DB. This is a confirmed bug of DB. You may disable this warnings, see L<"PERL_BADFREE">. =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 be present during testing. =item F<*/sh.exe>: ln: not found =item C: /dev: No such file or directory The last two should be self-explanatory. The test suite discovers that the system it runs on is not I *nixish. =back A lot of `bad free'... in databases, bug in DB confirmed on other platforms. You may disable it by setting PERL_BADFREE environment variable to 1. =head2 Installing the built perl Run make install It would put the generated files into needed locations. Manually put F, F and F to a location on your C, F to a location on your C. Run make cmdscripts INSTALLCMDDIR=d:/ir/on/path to convert perl utilities to F<.cmd> files and put them on C. 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, see L. =head2 C-style build Proceed as above, but make F (see L<"perl_.exe">) by make perl_ test and install by make aout_test make aout_install Manually put F to a location on your C. Since C has the extensions prebuilt, it does not suffer from the I 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 The build process for C I 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. =head2 C<'errno'> - unresolved external You do not have MT-safe F. See L. =head2 Problems with C reported with very old version of C. =head2 Some problem (forget which ;-) You have an older version of F on your C, which broke the build of extensions. =head2 Library ... not found You did not run C. See L. =head2 Segfault in make You use an old version of C make. See L. =head1 Specific (mis)features of OS/2 port =head2 C, C 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 Multi-argument form of C allows an additional numeric argument. The meaning of this argument is described in L. =head2 Additional modules: L, L, L, L. This modules provide access to additional numeric argument for C, 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, and C, are included into my ftp directory, mirrored on CPAN. =head2 Prebuilt methods: =over 4 =item C used by C, see L. =item C used by C for DLL name mangling. =item C Self explanatory. =item C leaves drive as it is. =item C =item C means has drive letter and is_rooted. =item C means has leading C<[/\\]> (maybe after a drive-letter:). =item C means changes with current dir. =item C Interface to cwd from B. Used by C. =item C Really really odious function to implement. Returns absolute name of file which would have C if CWD were C. C defaults to the current dir. =item C is present and I, works with END_LIBPATH, otherwise with C. =item C Set current value of extended library search path. If C is present and I, works with END_LIBPATH, otherwise with C. =back (Note that some of these may be moved to different libraries - eventually). =head2 Misfeatures =over 4 =item Since is present in B, but is not functional, the same is true for perl. Here is the list of things which may be "broken" on EMX (from EMX docs): - The functions recvmsg(), sendmsg(), and socketpair() are not implemented. - sock_init() is not required and not implemented. - flock() is not yet implemented (dummy function). - kill: Special treatment of PID=0, PID=1 and PID=-1 is not implemented. - waitpid: WUNTRACED Not implemented. waitpid() is not implemented for negative values of PID. Note that C does not work with the current version of EMX. =item Since F is used for globing (see L), the bugs of F plague perl as well. In particular, uppercase letters do not work in C<[...]>-patterns with the current C. =back =head2 Modifications Perl modifies some standard C library calls in the following ways: =over 9 =item C C uses F if shell is required, cf. L<"PERL_SH_DIR">. =item C is created using C or C environment variable, via C. =item C If the current directory is not writable, file is created using modified C, so there may be a race condition. =item C a dummy implementation. =item C C special-cases F and F. =back =head1 Perl flavors Because of idiosyncrasies of OS/2 one cannot have all the eggs in the same basket (though C 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 The main workhorse. This is a chimera executable: it is compiled as an C-style executable, but is linked with C-style dynamic library F, and with dynamic B DLL. This executable is a C application. It can load perl dynamic extensions, and it can fork(). Unfortunately, with the current version of B it cannot fork() with dynamic extensions loaded (may be fixed by patches to B). B Keep in mind that fork() is needed to open a pipe to yourself. =head2 F This is a statically linked C-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, like fork()ing when having some standard extension loaded. This executable is a C application. B A better behaviour could be obtained from C if it were statically linked with standard I, but dynamically linked with the I and C DLL. Then it would be able to fork() with standard extensions, I would be able to dynamically load arbitrary extensions. Some changes to Makefiles and hint files should be necessary to achieve this. I The friends locked into C 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 This is the same executable as , but it is a C application. B Usually C, C, and C of a C application are redirected to C. However, it is possible to see them if you start C from a PM program which emulates a console window, like I of C or C. Thus it I to use Perl debugger (see L) to debug your PM application. This flavor is required if you load extensions which use C, like the forthcoming C. =head2 F This is an C-style executable which is dynamically linked to F and C DLL. I know no advantages of this executable over C, but it cannot fork() at all. Well, one advantage is that the build process is not so convoluted as with C. It is a C application. =head2 Why strange names? Since Perl processes the C<#!>-line (cf. L, L, L, L), it should know when a program I. 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 increases the load time for the application (as well as the number of problems during compilation). Since interpreter is in a DLL, the C is basically forced to reside in a DLL as well (otherwise extensions would not be able to use C). =head2 Why chimera build? Current C environment does not allow DLLs compiled using Unixish C format to export symbols for data. This forces C-style compile of F. Current C environment does not allow F<.EXE> files compiled in C 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-style compile of F. =head1 ENVIRONMENT Here we list environment variables with are either OS/2-specific, or are more important under OS/2 than under other OSes. =head2 C Specific for OS/2. Should have the form path1;path2 or path1 path2 If the beginning of some prebuilt path matches F, it is substituted with F. Should be used if the perl library is moved from the default location in preference to C, since this would not leave wrong entries in <@INC>. =head2 C If 1, perl ignores setlocale() failing. May be useful with some strange Is. =head2 C 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 Specific for OS/2. Gives the directory part of the location for F. =head2 C or C Specific for OS/2. 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 and C 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 C DLL. Perl itself is not multithread-safe, as is not perl malloc(). However, extensions may use multiple thread on their own risk. Needed to compile C for C 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 perl needs to call an external program I, the F 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 as well (I use one from pdksh). The drive F: above is set up automatically during the build to a correct value on the builder machine, but is overridable at runtime, B a consensus on C was that perl should use one non-overridable shell per platform. The obvious choices for OS/2 are F and F. Having perl build itself would be impossible with F as a shell, thus I picked up C. Thus assures almost 100% compatibility with the scripts coming from *nix. B currently F of C calls external programs via fork()/exec(), and there is I 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 did not change). This means that 1 I copy of F 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 unless needed (metachars found). One can always start F explicitly via system 'cmd', '/c', 'mycmd', 'arg1', 'arg2', ... If you need to use F, 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. 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. If you have some working code for C, please send it to me, I will include it into distribution. I have no need for such a module, so cannot test it. =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. Unfortunately, it is also quite frivolous with memory usage as well. Since kitchen-top machines are usually low on memory, perl is compiled with all the possible memory-saving options. This probably makes perl's malloc() as greedy with memory as the neighbor's malloc(), but still much quickier. Note that this is true only for a "typical" usage, it is possible that the perl malloc will be worse for some very special usage. 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 added. (Currently only DLL perl has this, it should propagate to F shortly.) =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. 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