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perlport - Writing portable Perl |
perlport - Writing portable Perl
Perl runs on numerous operating systems. While most of them share much in common, they also have their own unique features.
This document is meant to help you to find out what constitutes portable Perl code. That way once you make a decision to write portably, you know where the lines are drawn, and you can stay within them.
There is a tradeoff between taking full advantage of one particular type of computer and taking advantage of a full range of them. Naturally, as you broaden your range and become more diverse, the common factors drop, and you are left with an increasingly smaller area of common ground in which you can operate to accomplish a particular task. Thus, when you begin attacking a problem, it is important to consider under which part of the tradeoff curve you want to operate. Specifically, you must decide whether it is important that the task that you are coding have the full generality of being portable, or whether to just get the job done right now. This is the hardest choice to be made. The rest is easy, because Perl provides many choices, whichever way you want to approach your problem.
Looking at it another way, writing portable code is usually about willfully limiting your available choices. Naturally, it takes discipline and sacrifice to do that. The product of portability and convenience may be a constant. You have been warned.
Be aware of two important points:
Here's the general rule: When you approach a task commonly done using a whole range of platforms, think about writing portable code. That way, you don't sacrifice much by way of the implementation choices you can avail yourself of, and at the same time you can give your users lots of platform choices. On the other hand, when you have to take advantage of some unique feature of a particular platform, as is often the case with systems programming (whether for Unix, Windows, Mac OS, VMS, etc.), consider writing platform-specific code.
When the code will run on only two or three operating systems, you may need to consider only the differences of those particular systems. The important thing is to decide where the code will run and to be deliberate in your decision.
The material below is separated into three main sections: main issues of portability (ISSUES, platform-specific issues (PLATFORMS, and built-in perl functions that behave differently on various ports (FUNCTION IMPLEMENTATIONS.
This information should not be considered complete; it includes possibly transient information about idiosyncrasies of some of the ports, almost all of which are in a state of constant evolution. Thus, this material should be considered a perpetual work in progress (<IMG SRC=``yellow_sign.gif'' ALT=``Under Construction''>).
In most operating systems, lines in files are terminated by newlines.
Just what is used as a newline may vary from OS to OS. Unix
traditionally uses \012, one type of DOSish I/O uses \015\012,
and Mac OS uses \015.
Perl uses \n to represent the ``logical'' newline, where what is
logical may depend on the platform in use. In MacPerl, \n always
means \015. In DOSish perls, \n usually means \012, but
when accessing a file in ``text'' mode, STDIO translates it to (or
from) \015\012, depending on whether you're reading or writing.
Unix does the same thing on ttys in canonical mode. \015\012
is commonly referred to as CRLF.
A common cause of unportable programs is the misuse of chop() to trim
newlines:
# XXX UNPORTABLE!
while(<FILE>) {
chop;
@array = split(/:/);
#...
}
You can get away with this on Unix and MacOS (they have a single
character end-of-line), but the same program will break under DOSish
perls because you're only chop()ing half the end-of-line. Instead,
chomp() should be used to trim newlines. The Dunce::Files module can
help audit your code for misuses of chop().
When dealing with binary files (or text files in binary mode) be sure to explicitly set $/ to the appropriate value for your file format before using chomp().
Because of the ``text'' mode translation, DOSish perls have limitations
in using seek and tell on a file accessed in ``text'' mode.
Stick to seek-ing to locations you got from tell (and no
others), and you are usually free to use seek and tell even
in ``text'' mode. Using seek or tell or other file operations
may be non-portable. If you use binmode on a file, however, you
can usually seek and tell with arbitrary values in safety.
A common misconception in socket programming is that \n eq \012
everywhere. When using protocols such as common Internet protocols,
\012 and \015 are called for specifically, and the values of
the logical \n and \r (carriage return) are not reliable.
print SOCKET "Hi there, client!\r\n"; # WRONG
print SOCKET "Hi there, client!\015\012"; # RIGHT
However, using \015\012 (or \cM\cJ, or \x0D\x0A) can be tedious
and unsightly, as well as confusing to those maintaining the code. As
such, the Socket module supplies the Right Thing for those who want it.
use Socket qw(:DEFAULT :crlf);
print SOCKET "Hi there, client!$CRLF" # RIGHT
When reading from a socket, remember that the default input record
separator $/ is \n, but robust socket code will recognize as
either \012 or \015\012 as end of line:
while (<SOCKET>) {
# ...
}
Because both CRLF and LF end in LF, the input record separator can be set to LF and any CR stripped later. Better to write:
use Socket qw(:DEFAULT :crlf);
local($/) = LF; # not needed if $/ is already \012
while (<SOCKET>) {
s/$CR?$LF/\n/; # not sure if socket uses LF or CRLF, OK
# s/\015?\012/\n/; # same thing
}
This example is preferred over the previous one--even for Unix
platforms--because now any \015's (\cM's) are stripped out
(and there was much rejoicing).
Similarly, functions that return text data--such as a function that fetches a web page--should sometimes translate newlines before returning the data, if they've not yet been translated to the local newline representation. A single line of code will often suffice:
$data =~ s/\015?\012/\n/g;
return $data;
Some of this may be confusing. Here's a handy reference to the ASCII CR and LF characters. You can print it out and stick it in your wallet.
LF == \012 == \x0A == \cJ == ASCII 10
CR == \015 == \x0D == \cM == ASCII 13
| Unix | DOS | Mac |
---------------------------
\n | LF | LF | CR |
\r | CR | CR | LF |
\n * | LF | CRLF | CR |
\r * | CR | CR | LF |
---------------------------
* text-mode STDIO
The Unix column assumes that you are not accessing a serial line (like a tty) in canonical mode. If you are, then CR on input becomes ``\n'', and ``\n'' on output becomes CRLF.
These are just the most common definitions of \n and \r in Perl.
There may well be others.
Different CPUs store integers and floating point numbers in different orders (called endianness) and widths (32-bit and 64-bit being the most common today). This affects your programs when they attempt to transfer numbers in binary format from one CPU architecture to another, usually either ``live'' via network connection, or by storing the numbers to secondary storage such as a disk file or tape.
Conflicting storage orders make utter mess out of the numbers. If a
little-endian host (Intel, VAX) stores 0x12345678 (305419896 in
decimal), a big-endian host (Motorola, Sparc, PA) reads it as
0x78563412 (2018915346 in decimal). Alpha and MIPS can be either:
Digital/Compaq used/uses them in little-endian mode; SGI/Cray uses
them in big-endian mode. To avoid this problem in network (socket)
connections use the pack and unpack formats n and N, the
``network'' orders. These are guaranteed to be portable.
You can explore the endianness of your platform by unpacking a data structure packed in native format such as:
print unpack("h*", pack("s2", 1, 2)), "\n";
# '10002000' on e.g. Intel x86 or Alpha 21064 in little-endian mode
# '00100020' on e.g. Motorola 68040
If you need to distinguish between endian architectures you could use either of the variables set like so:
$is_big_endian = unpack("h*", pack("s", 1)) =~ /01/;
$is_little_endian = unpack("h*", pack("s", 1)) =~ /^1/;
Differing widths can cause truncation even between platforms of equal endianness. The platform of shorter width loses the upper parts of the number. There is no good solution for this problem except to avoid transferring or storing raw binary numbers.
One can circumnavigate both these problems in two ways. Either transfer and store numbers always in text format, instead of raw binary, or else consider using modules like Data::Dumper (included in the standard distribution as of Perl 5.005) and Storable. Keeping all data as text significantly simplifies matters.
Most platforms these days structure files in a hierarchical fashion. So, it is reasonably safe to assume that all platforms support the notion of a ``path'' to uniquely identify a file on the system. How that path is really written, though, differs considerably.
Although similar, file path specifications differ between Unix, Windows, Mac OS, OS/2, VMS, VOS, RISC OS, and probably others. Unix, for example, is one of the few OSes that has the elegant idea of a single root directory.
DOS, OS/2, VMS, VOS, and Windows can work similarly to Unix with /
as path separator, or in their own idiosyncratic ways (such as having
several root directories and various ``unrooted'' device files such NIL:
and LPT:).
Mac OS uses : as a path separator instead of /.
The filesystem may support neither hard links (link) nor
symbolic links (symlink, readlink, lstat).
The filesystem may support neither access timestamp nor change timestamp (meaning that about the only portable timestamp is the modification timestamp), or one second granularity of any timestamps (e.g. the FAT filesystem limits the time granularity to two seconds).
VOS perl can emulate Unix filenames with / as path separator. The
native pathname characters greater-than, less-than, number-sign, and
percent-sign are always accepted.
RISC OS perl can emulate Unix filenames with / as path
separator, or go native and use . for path separator and : to
signal filesystems and disk names.
If all this is intimidating, have no (well, maybe only a little) fear. There are modules that can help. The File::Spec modules provide methods to do the Right Thing on whatever platform happens to be running the program.
use File::Spec::Functions;
chdir(updir()); # go up one directory
$file = catfile(curdir(), 'temp', 'file.txt');
# on Unix and Win32, './temp/file.txt'
# on Mac OS, ':temp:file.txt'
# on VMS, '[.temp]file.txt'
File::Spec is available in the standard distribution as of version 5.004_05. File::Spec::Functions is only in File::Spec 0.7 and later, and some versions of perl come with version 0.6. If File::Spec is not updated to 0.7 or later, you must use the object-oriented interface from File::Spec (or upgrade File::Spec).
In general, production code should not have file paths hardcoded. Making them user-supplied or read from a configuration file is better, keeping in mind that file path syntax varies on different machines.
This is especially noticeable in scripts like Makefiles and test suites,
which often assume / as a path separator for subdirectories.
Also of use is File::Basename from the standard distribution, which splits a pathname into pieces (base filename, full path to directory, and file suffix).
Even when on a single platform (if you can call Unix a single platform), remember not to count on the existence or the contents of particular system-specific files or directories, like /etc/passwd, /etc/sendmail.conf, /etc/resolv.conf, or even /tmp/. For example, /etc/passwd may exist but not contain the encrypted passwords, because the system is using some form of enhanced security. Or it may not contain all the accounts, because the system is using NIS. If code does need to rely on such a file, include a description of the file and its format in the code's documentation, then make it easy for the user to override the default location of the file.
Don't assume a text file will end with a newline. They should, but people forget.
Do not have two files of the same name with different case, like
test.pl and Test.pl, as many platforms have case-insensitive
filenames. Also, try not to have non-word characters (except for .)
in the names, and keep them to the 8.3 convention, for maximum
portability, onerous a burden though this may appear.
Likewise, when using the AutoSplit module, try to keep your functions to 8.3 naming and case-insensitive conventions; or, at the least, make it so the resulting files have a unique (case-insensitively) first 8 characters.
Whitespace in filenames is tolerated on most systems, but not all.
Many systems (DOS, VMS) cannot have more than one . in their filenames.
Don't assume > won't be the first character of a filename.
Always use < explicitly to open a file for reading,
unless you want the user to be able to specify a pipe open.
open(FILE, "< $existing_file") or die $!;
If filenames might use strange characters, it is safest to open it
with sysopen instead of open. open is magic and can
translate characters like >, <, and |, which may
be the wrong thing to do. (Sometimes, though, it's the right thing.)
Not all platforms provide a command line. These are usually platforms that rely primarily on a Graphical User Interface (GUI) for user interaction. A program requiring a command line interface might not work everywhere. This is probably for the user of the program to deal with, so don't stay up late worrying about it.
Some platforms can't delete or rename files held open by the system.
Remember to close files when you are done with them. Don't
unlink or rename an open file. Don't tie or open a
file already tied or opened; untie or close it first.
Don't open the same file more than once at a time for writing, as some operating systems put mandatory locks on such files.
Don't count on a specific environment variable existing in %ENV.
Don't count on %ENV entries being case-sensitive, or even
case-preserving. Don't try to clear %ENV by saying %ENV = ();, or,
if you really have to, make it conditional on $^O ne 'VMS' since in
VMS the %ENV table is much more than a per-process key-value string
table.
Don't count on signals or %SIG for anything.
Don't count on filename globbing. Use opendir, readdir, and
closedir instead.
Don't count on per-program environment variables, or per-program current directories.
Don't count on specific values of $!.
In general, don't directly access the system in code meant to be
portable. That means, no system, exec, fork, pipe,
``, qx//, open with a |, nor any of the other things
that makes being a perl hacker worth being.
Commands that launch external processes are generally supported on most platforms (though many of them do not support any type of forking). The problem with using them arises from what you invoke them on. External tools are often named differently on different platforms, may not be available in the same location, might accept different arguments, can behave differently, and often present their results in a platform-dependent way. Thus, you should seldom depend on them to produce consistent results. (Then again, if you're calling netstat -a, you probably don't expect it to run on both Unix and CP/M.)
One especially common bit of Perl code is opening a pipe to sendmail:
open(MAIL, '|/usr/lib/sendmail -t')
or die "cannot fork sendmail: $!";
This is fine for systems programming when sendmail is known to be available. But it is not fine for many non-Unix systems, and even some Unix systems that may not have sendmail installed. If a portable solution is needed, see the various distributions on CPAN that deal with it. Mail::Mailer and Mail::Send in the MailTools distribution are commonly used, and provide several mailing methods, including mail, sendmail, and direct SMTP (via Net::SMTP) if a mail transfer agent is not available. Mail::Sendmail is a standalone module that provides simple, platform-independent mailing.
The Unix System V IPC (msg*(), sem*(), shm*()) is not available
even on all Unix platforms.
The rule of thumb for portable code is: Do it all in portable Perl, or use a module (that may internally implement it with platform-specific code, but expose a common interface).
XS code can usually be made to work with any platform, but dependent libraries, header files, etc., might not be readily available or portable, or the XS code itself might be platform-specific, just as Perl code might be. If the libraries and headers are portable, then it is normally reasonable to make sure the XS code is portable, too.
A different type of portability issue arises when writing XS code: availability of a C compiler on the end-user's system. C brings with it its own portability issues, and writing XS code will expose you to some of those. Writing purely in Perl is an easier way to achieve portability.
In general, the standard modules work across platforms. Notable exceptions are the CPAN module (which currently makes connections to external programs that may not be available), platform-specific modules (like ExtUtils::MM_VMS), and DBM modules.
There is no one DBM module available on all platforms. SDBM_File and the others are generally available on all Unix and DOSish ports, but not in MacPerl, where only NBDM_File and DB_File are available.
The good news is that at least some DBM module should be available, and AnyDBM_File will use whichever module it can find. Of course, then the code needs to be fairly strict, dropping to the greatest common factor (e.g., not exceeding 1K for each record), so that it will work with any DBM module. See the AnyDBM_File manpage for more details.
The system's notion of time of day and calendar date is controlled in
widely different ways. Don't assume the timezone is stored in $ENV{TZ},
and even if it is, don't assume that you can control the timezone through
that variable.
Don't assume that the epoch starts at 00:00:00, January 1, 1970,
because that is OS- and implementation-specific. It is better to store a date
in an unambiguous representation. The ISO-8601 standard defines
``YYYY-MM-DD'' as the date format. A text representation (like ``1987-12-18'')
can be easily converted into an OS-specific value using a module like
Date::Parse. An array of values, such as those returned by
localtime, can be converted to an OS-specific representation using
Time::Local.
When calculating specific times, such as for tests in time or date modules, it may be appropriate to calculate an offset for the epoch.
require Time::Local;
$offset = Time::Local::timegm(0, 0, 0, 1, 0, 70);
The value for $offset in Unix will be 0, but in Mac OS will be
some large number. $offset can then be added to a Unix time value
to get what should be the proper value on any system.
Assume little about character sets. Assume nothing about
numerical values (ord, chr) of characters. Do not
assume that the alphabetic characters are encoded contiguously (in
the numeric sense). Do not assume anything about the ordering of the
characters. The lowercase letters may come before or after the
uppercase letters; the lowercase and uppercase may be interlaced so
that both `a' and `A' come before `b'; the accented and other
international characters may be interlaced so that ä comes
before `b'.
If you may assume POSIX (a rather large assumption), you may read more about the POSIX locale system from the perllocale manpage. The locale system at least attempts to make things a little bit more portable, or at least more convenient and native-friendly for non-English users. The system affects character sets and encoding, and date and time formatting--amongst other things.
If your code is destined for systems with severely constrained (or missing!) virtual memory systems then you want to be especially mindful of avoiding wasteful constructs such as:
# NOTE: this is no longer "bad" in perl5.005
for (0..10000000) {} # bad
for (my $x = 0; $x <= 10000000; ++$x) {} # good
@lines = <VERY_LARGE_FILE>; # bad
while (<FILE>) {$file .= $_} # sometimes bad
$file = join('', <FILE>); # better
The last two constructs may appear unintuitive to most people. The first repeatedly grows a string, whereas the second allocates a large chunk of memory in one go. On some systems, the second is more efficient that the first.
Most multi-user platforms provide basic levels of security, usually implemented at the filesystem level. Some, however, do not--unfortunately. Thus the notion of user id, or ``home'' directory, or even the state of being logged-in, may be unrecognizable on many platforms. If you write programs that are security-conscious, it is usually best to know what type of system you will be running under so that you can write code explicitly for that platform (or class of platforms).
For those times when it is necessary to have platform-specific code,
consider keeping the platform-specific code in one place, making porting
to other platforms easier. Use the Config module and the special
variable $^O to differentiate platforms, as described in
PLATFORMS.
Be careful in the tests you supply with your module or programs.
Module code may be fully portable, but its tests might not be. This
often happens when tests spawn off other processes or call external
programs to aid in the testing, or when (as noted above) the tests
assume certain things about the filesystem and paths. Be careful
not to depend on a specific output style for errors, such as when
checking $! after an system call. Some platforms expect a certain
output format, and perl on those platforms may have been adjusted
accordingly. Most specifically, don't anchor a regex when testing
an error value.
Modules uploaded to CPAN are tested by a variety of volunteers on different platforms. These CPAN testers are notified by mail of each new upload, and reply to the list with PASS, FAIL, NA (not applicable to this platform), or UNKNOWN (unknown), along with any relevant notations.
The purpose of the testing is twofold: one, to help developers fix any problems in their code that crop up because of lack of testing on other platforms; two, to provide users with information about whether a given module works on a given platform.
As of version 5.002, Perl is built with a $^O variable that
indicates the operating system it was built on. This was implemented
to help speed up code that would otherwise have to use Config
and use the value of $Config{osname}. Of course, to get more
detailed information about the system, looking into %Config is
certainly recommended.
%Config cannot always be trusted, however, because it was built
at compile time. If perl was built in one place, then transferred
elsewhere, some values may be wrong. The values may even have been
edited after the fact.
Perl works on a bewildering variety of Unix and Unix-like platforms (see
e.g. most of the files in the hints/ directory in the source code kit).
On most of these systems, the value of $^O (hence $Config{'osname'},
too) is determined either by lowercasing and stripping punctuation from the
first field of the string returned by typing uname -a (or a similar command)
at the shell prompt or by testing the file system for the presence of
uniquely named files such as a kernel or header file. Here, for example,
are a few of the more popular Unix flavors:
uname $^O $Config{'archname'}
--------------------------------------------
AIX aix aix
BSD/OS bsdos i386-bsdos
dgux dgux AViiON-dgux
DYNIX/ptx dynixptx i386-dynixptx
FreeBSD freebsd freebsd-i386
Linux linux arm-linux
Linux linux i386-linux
Linux linux i586-linux
Linux linux ppc-linux
HP-UX hpux PA-RISC1.1
IRIX irix irix
Mac OS X rhapsody rhapsody
MachTen PPC machten powerpc-machten
NeXT 3 next next-fat
NeXT 4 next OPENSTEP-Mach
openbsd openbsd i386-openbsd
OSF1 dec_osf alpha-dec_osf
reliantunix-n svr4 RM400-svr4
SCO_SV sco_sv i386-sco_sv
SINIX-N svr4 RM400-svr4
sn4609 unicos CRAY_C90-unicos
sn6521 unicosmk t3e-unicosmk
sn9617 unicos CRAY_J90-unicos
SunOS solaris sun4-solaris
SunOS solaris i86pc-solaris
SunOS4 sunos sun4-sunos
Because the value of $Config{archname} may depend on the
hardware architecture, it can vary more than the value of $^O.
Perl has long been ported to Intel-style microcomputers running under systems like PC-DOS, MS-DOS, OS/2, and most Windows platforms you can bring yourself to mention (except for Windows CE, if you count that). Users familiar with COMMAND.COM or CMD.EXE style shells should be aware that each of these file specifications may have subtle differences:
$filespec0 = "c:/foo/bar/file.txt";
$filespec1 = "c:\\foo\\bar\\file.txt";
$filespec2 = 'c:\foo\bar\file.txt';
$filespec3 = 'c:\\foo\\bar\\file.txt';
System calls accept either / or \ as the path separator.
However, many command-line utilities of DOS vintage treat / as
the option prefix, so may get confused by filenames containing /.
Aside from calling any external programs, / will work just fine,
and probably better, as it is more consistent with popular usage,
and avoids the problem of remembering what to backwhack and what
not to.
The DOS FAT filesystem can accommodate only ``8.3'' style filenames. Under
the ``case-insensitive, but case-preserving'' HPFS (OS/2) and NTFS (NT)
filesystems you may have to be careful about case returned with functions
like readdir or used with functions like open or opendir.
DOS also treats several filenames as special, such as AUX, PRN, NUL, CON, COM1, LPT1, LPT2, etc. Unfortunately, sometimes these filenames won't even work if you include an explicit directory prefix. It is best to avoid such filenames, if you want your code to be portable to DOS and its derivatives. It's hard to know what these all are, unfortunately.
Users of these operating systems may also wish to make use of scripts such as pl2bat.bat or pl2cmd to put wrappers around your scripts.
Newline (\n) is translated as \015\012 by STDIO when reading from
and writing to files (see Newlines). binmode(FILEHANDLE)
will keep \n translated as \012 for that filehandle. Since it is a
no-op on other systems, binmode should be used for cross-platform code
that deals with binary data. That's assuming you realize in advance
that your data is in binary. General-purpose programs should
often assume nothing about their data.
The $^O variable and the $Config{archname} values for various
DOSish perls are as follows:
OS $^O $Config{'archname'}
--------------------------------------------
MS-DOS dos
PC-DOS dos
OS/2 os2
Windows 95 MSWin32 MSWin32-x86
Windows 98 MSWin32 MSWin32-x86
Windows NT MSWin32 MSWin32-x86
Windows NT MSWin32 MSWin32-ALPHA
Windows NT MSWin32 MSWin32-ppc
Cygwin cygwin
The various MSWin32 Perl's can distinguish the OS they are running on via the value of the fifth element of the list returned from Win32::GetOSVersion(). For example:
if ($^O eq 'MSWin32') {
my @os_version_info = Win32::GetOSVersion();
print +('3.1','95','NT')[$os_version_info[4]],"\n";
}
Also see:
Win32::* modules in the Win32 manpage.
Any module requiring XS compilation is right out for most people, because MacPerl is built using non-free (and non-cheap!) compilers. Some XS modules that can work with MacPerl are built and distributed in binary form on CPAN.
Directories are specified as:
volume:folder:file for absolute pathnames
volume:folder: for absolute pathnames
:folder:file for relative pathnames
:folder: for relative pathnames
:file for relative pathnames
file for relative pathnames
Files are stored in the directory in alphabetical order. Filenames are
limited to 31 characters, and may include any character except for
null and :, which is reserved as the path separator.
Instead of flock, see FSpSetFLock and FSpRstFLock in the
Mac::Files module, or chmod(0444, ...) and chmod(0666, ...).
In the MacPerl application, you can't run a program from the command line;
programs that expect @ARGV to be populated can be edited with something
like the following, which brings up a dialog box asking for the command
line arguments.
if (!@ARGV) {
@ARGV = split /\s+/, MacPerl::Ask('Arguments?');
}
A MacPerl script saved as a ``droplet'' will populate @ARGV with the full
pathnames of the files dropped onto the script.
Mac users can run programs under a type of command line interface under MPW (Macintosh Programmer's Workshop, a free development environment from Apple). MacPerl was first introduced as an MPW tool, and MPW can be used like a shell:
perl myscript.plx some arguments
ToolServer is another app from Apple that provides access to MPW tools
from MPW and the MacPerl app, which allows MacPerl programs to use
system, backticks, and piped open.
``Mac OS'' is the proper name for the operating system, but the value
in $^O is ``MacOS''. To determine architecture, version, or whether
the application or MPW tool version is running, check:
$is_app = $MacPerl::Version =~ /App/;
$is_tool = $MacPerl::Version =~ /MPW/;
($version) = $MacPerl::Version =~ /^(\S+)/;
$is_ppc = $MacPerl::Architecture eq 'MacPPC';
$is_68k = $MacPerl::Architecture eq 'Mac68K';
Mac OS X and Mac OS X Server, based on NeXT's OpenStep OS, will (in theory) be able to run MacPerl natively, under the ``Classic'' environment. The new ``Cocoa'' environment (formerly called the ``Yellow Box'') may run a slightly modified version of MacPerl, using the Carbon interfaces.
Mac OS X Server and its Open Source version, Darwin, both run Unix perl natively (with a few patches). Full support for these is slated for perl 5.6.
Also see:
Perl on VMS is discussed in the perlvms manpage in the perl distribution. Perl on VMS can accept either VMS- or Unix-style file specifications as in either of the following:
$ perl -ne "print if /perl_setup/i" SYS$LOGIN:LOGIN.COM
$ perl -ne "print if /perl_setup/i" /sys$login/login.com
but not a mixture of both as in:
$ perl -ne "print if /perl_setup/i" sys$login:/login.com
Can't open sys$login:/login.com: file specification syntax error
Interacting with Perl from the Digital Command Language (DCL) shell often requires a different set of quotation marks than Unix shells do. For example:
$ perl -e "print ""Hello, world.\n"""
Hello, world.
There are several ways to wrap your perl scripts in DCL .COM files, if you are so inclined. For example:
$ write sys$output "Hello from DCL!"
$ if p1 .eqs. ""
$ then perl -x 'f$environment("PROCEDURE")
$ else perl -x - 'p1 'p2 'p3 'p4 'p5 'p6 'p7 'p8
$ deck/dollars="__END__"
#!/usr/bin/perl
print "Hello from Perl!\n";
__END__
$ endif
Do take care with $ ASSIGN/nolog/user SYS$COMMAND: SYS$INPUT if your
perl-in-DCL script expects to do things like $read = <STDIN>;.
Filenames are in the format ``name.extension;version''. The maximum
length for filenames is 39 characters, and the maximum length for
extensions is also 39 characters. Version is a number from 1 to
32767. Valid characters are /[A-Z0-9$_-]/.
VMS's RMS filesystem is case-insensitive and does not preserve case.
readdir returns lowercased filenames, but specifying a file for
opening remains case-insensitive. Files without extensions have a
trailing period on them, so doing a readdir with a file named A.;5
will return a. (though that file could be opened with
open(FH, 'A')).
RMS had an eight level limit on directory depths from any rooted logical
(allowing 16 levels overall) prior to VMS 7.2. Hence
PERL_ROOT:[LIB.2.3.4.5.6.7.8] is a valid directory specification but
PERL_ROOT:[LIB.2.3.4.5.6.7.8.9] is not. Makefile.PL authors might
have to take this into account, but at least they can refer to the former
as /PERL_ROOT/lib/2/3/4/5/6/7/8/.
The VMS::Filespec module, which gets installed as part of the build process on VMS, is a pure Perl module that can easily be installed on non-VMS platforms and can be helpful for conversions to and from RMS native formats.
What \n represents depends on the type of file opened. It could
be \015, \012, \015\012, or nothing. The VMS::Stdio module
provides access to the special fopen() requirements of files with unusual
attributes on VMS.
TCP/IP stacks are optional on VMS, so socket routines might not be implemented. UDP sockets may not be supported.
The value of $^O on OpenVMS is ``VMS''. To determine the architecture
that you are running on without resorting to loading all of %Config
you can examine the content of the @INC array like so:
if (grep(/VMS_AXP/, @INC)) {
print "I'm on Alpha!\n";
} elsif (grep(/VMS_VAX/, @INC)) {
print "I'm on VAX!\n";
} else {
print "I'm not so sure about where $^O is...\n";
}
On VMS, perl determines the UTC offset from the SYS$TIMEZONE_DIFFERENTIAL
logical name. Although the VMS epoch began at 17-NOV-1858 00:00:00.00,
calls to localtime are adjusted to count offsets from
01-JAN-1970 00:00:00.00, just like Unix.
Also see:
(Put the words subscribe vmsperl in message body.)
Perl on VOS is discussed in README.vos in the perl distribution (installed as the perlvos manpage). Perl on VOS can accept either VOS- or Unix-style file specifications as in either of the following:
$ perl -ne "print if /perl_setup/i" >system>notices
$ perl -ne "print if /perl_setup/i" /system/notices
or even a mixture of both as in:
$ perl -ne "print if /perl_setup/i" >system/notices
Even though VOS allows the slash character to appear in object names, because the VOS port of Perl interprets it as a pathname delimiting character, VOS files, directories, or links whose names contain a slash character cannot be processed. Such files must be renamed before they can be processed by Perl. Note that VOS limits file names to 32 or fewer characters.
See README.vos for restrictions that apply when Perl is built with the alpha version of VOS POSIX.1 support.
Perl on VOS is built without any extensions and does not support dynamic loading.
The value of $^O on VOS is ``VOS''. To determine the architecture that
you are running on without resorting to loading all of %Config you
can examine the content of the @INC array like so:
if ($^O =~ /VOS/) {
print "I'm on a Stratus box!\n";
} else {
print "I'm not on a Stratus box!\n";
die;
}
if (grep(/860/, @INC)) {
print "This box is a Stratus XA/R!\n";
} elsif (grep(/7100/, @INC)) {
print "This box is a Stratus HP 7100 or 8xxx!\n";
} elsif (grep(/8000/, @INC)) {
print "This box is a Stratus HP 8xxx!\n";
} else {
print "This box is a Stratus 68K!\n";
}
Also see:
There is no specific mailing list for Perl on VOS. You can post comments to the comp.sys.stratus newsgroup, or subscribe to the general Stratus mailing list. Send a letter with ``Subscribe Info-Stratus'' in the message body to majordomo@list.stratagy.com.
Recent versions of Perl have been ported to platforms such as OS/400 on AS/400 minicomputers as well as OS/390, VM/ESA, and BS2000 for S/390 Mainframes. Such computers use EBCDIC character sets internally (usually Character Code Set ID 0037 for OS/400 and either 1047 or POSIX-BC for S/390 systems). On the mainframe perl currently works under the ``Unix system services for OS/390'' (formerly known as OpenEdition), VM/ESA OpenEdition, or the BS200 POSIX-BC system (BS2000 is supported in perl 5.6 and greater). See the perlos390 manpage for details.
As of R2.5 of USS for OS/390 and Version 2.3 of VM/ESA these Unix
sub-systems do not support the #! shebang trick for script invocation.
Hence, on OS/390 and VM/ESA perl scripts can be executed with a header
similar to the following simple script:
: # use perl
eval 'exec /usr/local/bin/perl -S $0 ${1+"$@"}'
if 0;
#!/usr/local/bin/perl # just a comment really
print "Hello from perl!\n";
OS/390 will support the #! shebang trick in release 2.8 and beyond.
Calls to system and backticks can use POSIX shell syntax on all
S/390 systems.
On the AS/400, if PERL5 is in your library list, you may need to wrap your perl scripts in a CL procedure to invoke them like so:
BEGIN
CALL PGM(PERL5/PERL) PARM('/QOpenSys/hello.pl')
ENDPGM
This will invoke the perl script hello.pl in the root of the
QOpenSys file system. On the AS/400 calls to system or backticks
must use CL syntax.
On these platforms, bear in mind that the EBCDIC character set may have
an effect on what happens with some perl functions (such as chr,
pack, print, printf, ord, sort, sprintf, unpack), as
well as bit-fiddling with ASCII constants using operators like ^, &
and |, not to mention dealing with socket interfaces to ASCII computers
(see Newlines).
Fortunately, most web servers for the mainframe will correctly
translate the \n in the following statement to its ASCII equivalent
(\r is the same under both Unix and OS/390 & VM/ESA):
print "Content-type: text/html\r\n\r\n";
The values of $^O on some of these platforms includes:
uname $^O $Config{'archname'}
--------------------------------------------
OS/390 os390 os390
OS400 os400 os400
POSIX-BC posix-bc BS2000-posix-bc
VM/ESA vmesa vmesa
Some simple tricks for determining if you are running on an EBCDIC platform could include any of the following (perhaps all):
if ("\t" eq "\05") { print "EBCDIC may be spoken here!\n"; }
if (ord('A') == 193) { print "EBCDIC may be spoken here!\n"; }
if (chr(169) eq 'z') { print "EBCDIC may be spoken here!\n"; }
One thing you may not want to rely on is the EBCDIC encoding of punctuation characters since these may differ from code page to code page (and once your module or script is rumoured to work with EBCDIC, folks will want it to work with all EBCDIC character sets).
Also see:
the perlos390 manpage, README.os390, perlbs2000, README.vmesa, the perlebcdic manpage.
Because Acorns use ASCII with newlines (\n) in text files as \012 like
Unix, and because Unix filename emulation is turned on by default,
most simple scripts will probably work ``out of the box''. The native
filesystem is modular, and individual filesystems are free to be
case-sensitive or insensitive, and are usually case-preserving. Some
native filesystems have name length limits, which file and directory
names are silently truncated to fit. Scripts should be aware that the
standard filesystem currently has a name length limit of 10
characters, with up to 77 items in a directory, but other filesystems
may not impose such limitations.
Native filenames are of the form
Filesystem#Special_Field::DiskName.$.Directory.Directory.File
where
Special_Field is not usually present, but may contain . and $ .
Filesystem =~ m|[A-Za-z0-9_]|
DsicName =~ m|[A-Za-z0-9_/]|
$ represents the root directory
. is the path separator
@ is the current directory (per filesystem but machine global)
^ is the parent directory
Directory and File =~ m|[^\0- "\.\$\%\&:\@\\^\|\177]+|
The default filename translation is roughly tr|/.|./|;
Note that "ADFS::HardDisk.$.File" ne 'ADFS::HardDisk.$.File' and that
the second stage of $ interpolation in regular expressions will fall
foul of the $. if scripts are not careful.
Logical paths specified by system variables containing comma-separated
search lists are also allowed; hence System:Modules is a valid
filename, and the filesystem will prefix Modules with each section of
System$Path until a name is made that points to an object on disk.
Writing to a new file System:Modules would be allowed only if
System$Path contains a single item list. The filesystem will also
expand system variables in filenames if enclosed in angle brackets, so
<System$Dir>.Modules would look for the file
$ENV{'System$Dir'} . 'Modules'. The obvious implication of this is
that fully qualified filenames can start with <> and should
be protected when open is used for input.
Because . was in use as a directory separator and filenames could not
be assumed to be unique after 10 characters, Acorn implemented the C
compiler to strip the trailing .c .h .s and .o suffix from
filenames specified in source code and store the respective files in
subdirectories named after the suffix. Hence files are translated:
foo.h h.foo
C:foo.h C:h.foo (logical path variable)
sys/os.h sys.h.os (C compiler groks Unix-speak)
10charname.c c.10charname
10charname.o o.10charname
11charname_.c c.11charname (assuming filesystem truncates at 10)
The Unix emulation library's translation of filenames to native assumes
that this sort of translation is required, and it allows a user-defined list
of known suffixes that it will transpose in this fashion. This may
seem transparent, but consider that with these rules foo/bar/baz.h
and foo/bar/h/baz both map to foo.bar.h.baz, and that readdir and
glob cannot and do not attempt to emulate the reverse mapping. Other
.'s in filenames are translated to /.
As implied above, the environment accessed through %ENV is global, and
the convention is that program specific environment variables are of the
form Program$Name. Each filesystem maintains a current directory,
and the current filesystem's current directory is the global current
directory. Consequently, sociable programs don't change the current
directory but rely on full pathnames, and programs (and Makefiles) cannot
assume that they can spawn a child process which can change the current
directory without affecting its parent (and everyone else for that
matter).
Because native operating system filehandles are global and are currently
allocated down from 255, with 0 being a reserved value, the Unix emulation
library emulates Unix filehandles. Consequently, you can't rely on
passing STDIN, STDOUT, or STDERR to your children.
The desire of users to express filenames of the form
<Foo$Dir>.Bar on the command line unquoted causes problems,
too: `` command output capture has to perform a guessing game. It
assumes that a string <[^<>]+\$[^<>]> is a
reference to an environment variable, whereas anything else involving
< or > is redirection, and generally manages to be 99%
right. Of course, the problem remains that scripts cannot rely on any
Unix tools being available, or that any tools found have Unix-like command
line arguments.
Extensions and XS are, in theory, buildable by anyone using free
tools. In practice, many don't, as users of the Acorn platform are
used to binary distributions. MakeMaker does run, but no available
make currently copes with MakeMaker's makefiles; even if and when
this should be fixed, the lack of a Unix-like shell will cause
problems with makefile rules, especially lines of the form cd
sdbm && make all, and anything using quoting.
``RISC OS'' is the proper name for the operating system, but the value
in $^O is ``riscos'' (because we don't like shouting).
Perl has been ported to many platforms that do not fit into any of the categories listed above. Some, such as AmigaOS, Atari MiNT, BeOS, HP MPE/iX, QNX, Plan 9, and VOS, have been well-integrated into the standard Perl source code kit. You may need to see the ports/ directory on CPAN for information, and possibly binaries, for the likes of: aos, Atari ST, lynxos, riscos, Novell Netware, Tandem Guardian, etc. (Yes, we know that some of these OSes may fall under the Unix category, but we are not a standards body.)
Some approximate operating system names and their $^O values
in the ``OTHER'' category include:
OS $^O $Config{'archname'}
------------------------------------------
Amiga DOS amigaos m68k-amigos
MPE/iX mpeix PA-RISC1.1
See also:
Listed below are functions that are either completely unimplemented or else have been implemented differently on various platforms. Following each description will be, in parentheses, a list of platforms that the description applies to.
The list may well be incomplete, or even wrong in some places. When in doubt, consult the platform-specific README files in the Perl source distribution, and any other documentation resources accompanying a given port.
Be aware, moreover, that even among Unix-ish systems there are variations.
For many functions, you can also query %Config, exported by
default from the Config module. For example, to check whether the
platform has the lstat call, check $Config{d_lstat}. See
the Config manpage for a full description of available variables.
-r, -w, and -x have a limited meaning only; directories
and applications are executable, and there are no uid/gid
considerations. -o is not supported. (Mac OS)
-r, -w, -x, and -o tell whether the file is accessible,
which may not reflect UIC-based file protections. (VMS)
-s returns the size of the data fork, not the total size of data fork
plus resource fork. (Mac OS).
-s by name on an open file will return the space reserved on disk,
rather than the current extent. -s on an open filehandle returns the
current size. (RISC OS)
-R, -W, -X, -O are indistinguishable from -r, -w,
-x, -o. (Mac OS, Win32, VMS, RISC OS)
-b, -c, -k, -g, -p, -u, -A are not implemented.
(Mac OS)
-g, -k, -l, -p, -u, -A are not particularly meaningful.
(Win32, VMS, RISC OS)
-d is true if passed a device spec without an explicit directory.
(VMS)
-T and -B are implemented, but might misclassify Mac text files
with foreign characters; this is the case will all platforms, but may
affect Mac OS often. (Mac OS)
-x (or -X) determine if a file ends in one of the executable
suffixes. -S is meaningless. (Win32)
-x (or -X) determine if a file has an executable file type.
(RISC OS)
Reopens file and restores pointer; if function fails, underlying filehandle may be closed, or pointer may be in a different position. (VMS)
The value returned by tell may be affected after the call, and
the filehandle may be flushed. (Win32)
Only good for changing ``owner'' read-write access, ``group'', and ``other'' bits are meaningless. (Win32)
Only good for changing ``owner'' and ``other'' read-write access. (RISC OS)
Access permissions are mapped onto VOS access-control list changes. (VOS)
Does nothing, but won't fail. (Win32)
Not implemented. (VOS)
Not implemented. (Win32)
Invokes VMS debugger. (VMS)
Implemented via Spawn. (VM/ESA)
Does not automatically flush output handles on some platforms. (SunOS, Solaris, HP-UX)
Available only on Windows NT (not on Windows 95). (Win32)
Emulated using multiple interpreters. See the perlfork manpage. (Win32)
Does not automatically flush output handles on some platforms. (SunOS, Solaris, HP-UX)
Not useful. (RISC OS)
Not useful. (RISC OS)
* and ? metacharacters are supported.
(Mac OS)
This operator is implemented via the File::Glob extension on most platforms. See the File::Glob manpage for portability information.
Available only for socket handles, and it does what the ioctlsocket() call
in the Winsock API does. (Win32)
Available only for socket handles. (RISC OS)
kill() doesn't have the semantics of raise(), i.e. it doesn't send
a signal to the identified process like it does on Unix platforms.
Instead kill($sig, $pid) terminates the process identified by $pid,
and makes it exit immediately with exit status $sig. As in Unix, if
$sig is 0 and the specified process exists, it returns true without
actually terminating it. (Win32)
Link count not updated because hard links are not quite that hard (They are sort of half-way between hard and soft links). (AmigaOS)
Hard links are implemented on Win32 (Windows NT and Windows 2000) under NTFS only.
Return values (especially for device and inode) may be bogus. (Win32)
| variants are supported only if ToolServer is installed.
(Mac OS)
open to |- and -| are unsupported. (Mac OS, Win32, RISC OS)
Opening a process does not automatically flush output handles on some platforms. (SunOS, Solaris, HP-UX)
Very limited functionality. (MiNT)
Only reliable on sockets. (RISC OS)
Note that the socket FILEHANDLE form is generally portable.
mtime and atime are the same thing, and ctime is creation time instead of inode change time. (Mac OS)
device and inode are not meaningful. (Win32)
device and inode are not necessarily reliable. (VMS)
mtime, atime and ctime all return the last modification time. Device and inode are not necessarily reliable. (RISC OS)
dev, rdev, blksize, and blocks are not available. inode is not meaningful and will differ between stat calls on the same file. (os2)
Fcntl
(O_RDONLY, O_WRONLY, O_RDWR) should work everywhere though. (Mac
OS, OS/390, VM/ESA)
As an optimization, may not call the command shell specified in
$ENV{PERL5SHELL}. system(1, @args) spawns an external
process and immediately returns its process designator, without
waiting for it to terminate. Return value may be used subsequently
in wait or waitpid. Failure to spawn() a subprocess is indicated
by setting $? to ``255 << 8''. $? is set in a way compatible with
Unix (i.e. the exitstatus of the subprocess is obtained by ``$? >> 8'',
as described in the documentation). (Win32)
There is no shell to process metacharacters, and the native standard is
to pass a command line terminated by ``\n'' ``\r'' or ``\0'' to the spawned
program. Redirection such as > foo is performed (if at all) by
the run time library of the spawned program. system list will call
the Unix emulation library's exec emulation, which attempts to provide
emulation of the stdin, stdout, stderr in force in the parent, providing
the child program uses a compatible version of the emulation library.
scalar will call the native command line direct and no such emulation
of a child Unix program will exists. Mileage will vary. (RISC OS)
Far from being POSIX compliant. Because there may be no underlying /bin/sh tries to work around the problem by forking and execing the first token in its argument string. Handles basic redirection (``<'' or ``>'') on its own behalf. (MiNT)
Does not automatically flush output handles on some platforms. (SunOS, Solaris, HP-UX)
``cumulative'' times will be bogus. On anything other than Windows NT
or Windows 2000, ``system'' time will be bogus, and ``user'' time is
actually the time returned by the clock() function in the C runtime
library. (Win32)
Not useful. (RISC OS)
Truncation to zero-length only. (VOS)
If a FILEHANDLE is supplied, it must be writable and opened in append
mode (i.e., use open(FH, '>filename')>
or sysopen(FH,...,O_APPEND|O_RDWR). If a filename is supplied, it
should not be held open elsewhere. (Win32)
umask works but the correct permissions are set only when the file
is finally closed. (AmigaOS)
May not behave as expected. Behavior depends on the C runtime library's implementation of utime(), and the filesystem being used. The FAT filesystem typically does not support an ``access time'' field, and it may limit timestamps to a granularity of two seconds. (Win32)
Can only be applied to process handles returned for processes spawned
using system(1, ...) or pseudo processes created with fork(). (Win32)
Not useful. (RISC OS)
$^O values,
endianness, File::Spec, VMS, BS2000, OS/400.
Added a bunch of $^O and related values
for various platforms; fixed mail and web addresses, and added
and changed miscellaneous notes. (Peter Prymmer)
As of early 2001 (the Perl release 5.6.1), the following platforms are able to build Perl from the standard source code distribution available at http://www.perl.com/CPAN/src/index.html
AIX
AmigaOS
Darwin (Rhapsody)
DG/UX
DOS DJGPP 1)
DYNIX/ptx
EPOC
FreeBSD
HP-UX
IRIX
Linux
MachTen
MacOS Classic 2)
NonStop-UX
ReliantUNIX (SINIX)
OpenBSD
OpenVMS (VMS)
OS/2
OS X
QNX
Solaris
Tru64 UNIX (DEC OSF/1, Digital UNIX)
UNICOS
UNICOS/mk
VOS
Win32/NT/2K 3)
1) in DOS mode either the DOS or OS/2 ports can be used
2) Mac OS Classic (pre-X) is almost 5.6.1-ready; building from
the source does work with 5.6.1, but additional MacOS specific
source code is needed for a complete build. Contact the mailing
list macperl-porters@macperl.org for more information.
3) compilers: Borland, Cygwin, Mingw32 EGCS/GCC, VC++
The following platforms worked for the previous release (5.6.0), but we did not manage to test these in time for the 5.6.1 release. There is a very good chance that these will work fine with 5.6.1.
DomainOS
Hurd
LynxOS
MinGW
MPE/iX
NetBSD
PowerMAX
SCO SV
SunOS
SVR4
Unixware
Windows 3.1
Windows 95
Windows 98
Windows Me
The following platform worked for the 5.005_03 major release but not
5.6.0. Standardization on UTF-8 as the internal string representation
in 5.6.0 and 5.6.1 has introduced incompatibilities in this EBCDIC
platform. While Perl 5.6.1 will build on this platform some
regression tests may fail and the use utf8; pragma typically
introduces text handling errors. UTF-8 support for this platform may
be enabled in a future release:
OS/390 1)
1) previously known as MVS, about to become z/OS.
Strongly related to the OS/390 platform by also being EBCDIC-based mainframe platforms are the following platforms:
POSIX-BC (BS2000)
VM/ESA
These are also expected to work, albeit with no UTF-8 support, under 5.6.1 for the same reasons as OS/390. Contact the mailing list perl-mvs@perl.org for more details.
The following platforms have been known to build Perl from source in the past (5.005_03 and earlier), but we haven't been able to verify their status for the current release, either because the hardware/software platforms are rare or because we don't have an active champion on these platforms--or both. They used to work, though, so go ahead and try compiling them, and let perlbug@perl.org of any trouble.
3b1
A/UX
BeOS
BSD/OS
ConvexOS
CX/UX
DC/OSx
DDE SMES
DOS EMX
Dynix
EP/IX
ESIX
FPS
GENIX
Greenhills
ISC
MachTen 68k
MiNT
MPC
NEWS-OS
NextSTEP
OpenSTEP
Opus
Plan 9
PowerUX
RISC/os
SCO ODT/OSR
Stellar
SVR2
TI1500
TitanOS
Ultrix
Unisys Dynix
Unixware
UTS
Support for the following platform is planned for a future Perl release:
Netware
The following platforms have their own source code distributions and binaries available via http://www.perl.com/CPAN/ports/index.html:
Perl release
Netware 5.003_07
OS/400 5.005_02
Tandem Guardian 5.004
The following platforms have only binaries available via http://www.perl.com/CPAN/ports/index.html :
Perl release
Acorn RISCOS 5.005_02
AOS 5.002
LynxOS 5.004_02
Although we do suggest that you always build your own Perl from the source code, both for maximal configurability and for security, in case you are in a hurry you can check http://www.perl.com/CPAN/ports/index.html for binary distributions.
the perlaix manpage, the perlamiga manpage, the perlcygwin manpage, the perldos manpage, the perlepoc manpage, the perlebcdic manpage, the perlhpux manpage, the perlos2 manpage, the perlos390 manpage, the perlbs2000 manpage, the perlwin32 manpage, the perlvms manpage, the perlvos manpage, and the Win32 manpage.
Abigail <abigail@fnx.com>, Charles Bailey <bailey@newman.upenn.edu>, Graham Barr <gbarr@pobox.com>, Tom Christiansen <tchrist@perl.com>, Nicholas Clark <Nicholas.Clark@liverpool.ac.uk>, Thomas Dorner <Thomas.Dorner@start.de>, Andy Dougherty <doughera@lafcol.lafayette.edu>, Dominic Dunlop <domo@vo.lu>, Neale Ferguson <neale@mailbox.tabnsw.com.au>, David J. Fiander <davidf@mks.com>, Paul Green <Paul_Green@stratus.com>, M.J.T. Guy <mjtg@cus.cam.ac.uk>, Jarkko Hietaniemi <jhi@iki.fi>, Luther Huffman <lutherh@stratcom.com>, Nick Ing-Simmons <nick@ni-s.u-net.com>, Andreas J. König <koenig@kulturbox.de>, Markus Laker <mlaker@contax.co.uk>, Andrew M. Langmead <aml@world.std.com>, Larry Moore <ljmoore@freespace.net>, Paul Moore <Paul.Moore@uk.origin-it.com>, Chris Nandor <pudge@pobox.com>, Matthias Neeracher <neeri@iis.ee.ethz.ch>, Gary Ng <71564.1743@CompuServe.COM>, Tom Phoenix <rootbeer@teleport.com>, André Pirard <A.Pirard@ulg.ac.be>, Peter Prymmer <pvhp@forte.com>, Hugo van der Sanden <hv@crypt0.demon.co.uk>, Gurusamy Sarathy <gsar@activestate.com>, Paul J. Schinder <schinder@pobox.com>, Michael G Schwern <schwern@pobox.com>, Dan Sugalski <sugalskd@ous.edu>, Nathan Torkington <gnat@frii.com>.
This document is maintained by Chris Nandor <pudge@pobox.com>.
Version 1.47, last modified 22 March 2000
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perlport - Writing portable Perl |