3 perlport - Writing portable Perl
7 Perl runs on numerous operating systems. While most of them share
8 much in common, they also have their own unique features.
10 This document is meant to help you to find out what constitutes portable
11 Perl code. That way once you make a decision to write portably,
12 you know where the lines are drawn, and you can stay within them.
14 There is a tradeoff between taking full advantage of one particular
15 type of computer and taking advantage of a full range of them.
16 Naturally, as you broaden your range and become more diverse, the
17 common factors drop, and you are left with an increasingly smaller
18 area of common ground in which you can operate to accomplish a
19 particular task. Thus, when you begin attacking a problem, it is
20 important to consider under which part of the tradeoff curve you
21 want to operate. Specifically, you must decide whether it is
22 important that the task that you are coding have the full generality
23 of being portable, or whether to just get the job done right now.
24 This is the hardest choice to be made. The rest is easy, because
25 Perl provides many choices, whichever way you want to approach your
28 Looking at it another way, writing portable code is usually about
29 willfully limiting your available choices. Naturally, it takes
30 discipline and sacrifice to do that. The product of portability
31 and convenience may be a constant. You have been warned.
33 Be aware of two important points:
37 =item Not all Perl programs have to be portable
39 There is no reason you should not use Perl as a language to glue Unix
40 tools together, or to prototype a Macintosh application, or to manage the
41 Windows registry. If it makes no sense to aim for portability for one
42 reason or another in a given program, then don't bother.
44 =item Nearly all of Perl already I<is> portable
46 Don't be fooled into thinking that it is hard to create portable Perl
47 code. It isn't. Perl tries its level-best to bridge the gaps between
48 what's available on different platforms, and all the means available to
49 use those features. Thus almost all Perl code runs on any machine
50 without modification. But there are some significant issues in
51 writing portable code, and this document is entirely about those issues.
55 Here's the general rule: When you approach a task commonly done
56 using a whole range of platforms, think about writing portable
57 code. That way, you don't sacrifice much by way of the implementation
58 choices you can avail yourself of, and at the same time you can give
59 your users lots of platform choices. On the other hand, when you have to
60 take advantage of some unique feature of a particular platform, as is
61 often the case with systems programming (whether for Unix, Windows,
62 S<Mac OS>, VMS, etc.), consider writing platform-specific code.
64 When the code will run on only two or three operating systems, you
65 may need to consider only the differences of those particular systems.
66 The important thing is to decide where the code will run and to be
67 deliberate in your decision.
69 The material below is separated into three main sections: main issues of
70 portability (L<"ISSUES">, platform-specific issues (L<"PLATFORMS">, and
71 built-in perl functions that behave differently on various ports
72 (L<"FUNCTION IMPLEMENTATIONS">.
74 This information should not be considered complete; it includes possibly
75 transient information about idiosyncrasies of some of the ports, almost
76 all of which are in a state of constant evolution. Thus, this material
77 should be considered a perpetual work in progress
78 (<IMG SRC="yellow_sign.gif" ALT="Under Construction">).
84 In most operating systems, lines in files are terminated by newlines.
85 Just what is used as a newline may vary from OS to OS. Unix
86 traditionally uses C<\012>, one type of DOSish I/O uses C<\015\012>,
87 and S<Mac OS> uses C<\015>.
89 Perl uses C<\n> to represent the "logical" newline, where what is
90 logical may depend on the platform in use. In MacPerl, C<\n> always
91 means C<\015>. In DOSish perls, C<\n> usually means C<\012>, but
92 when accessing a file in "text" mode, STDIO translates it to (or
93 from) C<\015\012>, depending on whether you're reading or writing.
94 Unix does the same thing on ttys in canonical mode. C<\015\012>
95 is commonly referred to as CRLF.
97 A common cause of unportable programs is the misuse of chop() to trim
107 You can get away with this on Unix and MacOS (they have a single
108 character end-of-line), but the same program will break under DOSish
109 perls because you're only chop()ing half the end-of-line. Instead,
110 chomp() should be used to trim newlines. The Dunce::Files module can
111 help audit your code for misuses of chop().
113 When dealing with binary files (or text files in binary mode) be sure
114 to explicitly set $/ to the appropriate value for your file format
115 before using chomp().
117 Because of the "text" mode translation, DOSish perls have limitations
118 in using C<seek> and C<tell> on a file accessed in "text" mode.
119 Stick to C<seek>-ing to locations you got from C<tell> (and no
120 others), and you are usually free to use C<seek> and C<tell> even
121 in "text" mode. Using C<seek> or C<tell> or other file operations
122 may be non-portable. If you use C<binmode> on a file, however, you
123 can usually C<seek> and C<tell> with arbitrary values in safety.
125 A common misconception in socket programming is that C<\n> eq C<\012>
126 everywhere. When using protocols such as common Internet protocols,
127 C<\012> and C<\015> are called for specifically, and the values of
128 the logical C<\n> and C<\r> (carriage return) are not reliable.
130 print SOCKET "Hi there, client!\r\n"; # WRONG
131 print SOCKET "Hi there, client!\015\012"; # RIGHT
133 However, using C<\015\012> (or C<\cM\cJ>, or C<\x0D\x0A>) can be tedious
134 and unsightly, as well as confusing to those maintaining the code. As
135 such, the Socket module supplies the Right Thing for those who want it.
137 use Socket qw(:DEFAULT :crlf);
138 print SOCKET "Hi there, client!$CRLF" # RIGHT
140 When reading from a socket, remember that the default input record
141 separator C<$/> is C<\n>, but robust socket code will recognize as
142 either C<\012> or C<\015\012> as end of line:
148 Because both CRLF and LF end in LF, the input record separator can
149 be set to LF and any CR stripped later. Better to write:
151 use Socket qw(:DEFAULT :crlf);
152 local($/) = LF; # not needed if $/ is already \012
155 s/$CR?$LF/\n/; # not sure if socket uses LF or CRLF, OK
156 # s/\015?\012/\n/; # same thing
159 This example is preferred over the previous one--even for Unix
160 platforms--because now any C<\015>'s (C<\cM>'s) are stripped out
161 (and there was much rejoicing).
163 Similarly, functions that return text data--such as a function that
164 fetches a web page--should sometimes translate newlines before
165 returning the data, if they've not yet been translated to the local
166 newline representation. A single line of code will often suffice:
168 $data =~ s/\015?\012/\n/g;
171 Some of this may be confusing. Here's a handy reference to the ASCII CR
172 and LF characters. You can print it out and stick it in your wallet.
174 LF == \012 == \x0A == \cJ == ASCII 10
175 CR == \015 == \x0D == \cM == ASCII 13
178 ---------------------------
181 \n * | LF | CRLF | CR |
182 \r * | CR | CR | LF |
183 ---------------------------
186 The Unix column assumes that you are not accessing a serial line
187 (like a tty) in canonical mode. If you are, then CR on input becomes
188 "\n", and "\n" on output becomes CRLF.
190 These are just the most common definitions of C<\n> and C<\r> in Perl.
191 There may well be others.
193 =head2 Numbers endianness and Width
195 Different CPUs store integers and floating point numbers in different
196 orders (called I<endianness>) and widths (32-bit and 64-bit being the
197 most common today). This affects your programs when they attempt to transfer
198 numbers in binary format from one CPU architecture to another,
199 usually either "live" via network connection, or by storing the
200 numbers to secondary storage such as a disk file or tape.
202 Conflicting storage orders make utter mess out of the numbers. If a
203 little-endian host (Intel, VAX) stores 0x12345678 (305419896 in
204 decimal), a big-endian host (Motorola, Sparc, PA) reads it as
205 0x78563412 (2018915346 in decimal). Alpha and MIPS can be either:
206 Digital/Compaq used/uses them in little-endian mode; SGI/Cray uses
207 them in big-endian mode. To avoid this problem in network (socket)
208 connections use the C<pack> and C<unpack> formats C<n> and C<N>, the
209 "network" orders. These are guaranteed to be portable.
211 You can explore the endianness of your platform by unpacking a
212 data structure packed in native format such as:
214 print unpack("h*", pack("s2", 1, 2)), "\n";
215 # '10002000' on e.g. Intel x86 or Alpha 21064 in little-endian mode
216 # '00100020' on e.g. Motorola 68040
218 If you need to distinguish between endian architectures you could use
219 either of the variables set like so:
221 $is_big_endian = unpack("h*", pack("s", 1)) =~ /01/;
222 $is_little_endian = unpack("h*", pack("s", 1)) =~ /^1/;
224 Differing widths can cause truncation even between platforms of equal
225 endianness. The platform of shorter width loses the upper parts of the
226 number. There is no good solution for this problem except to avoid
227 transferring or storing raw binary numbers.
229 One can circumnavigate both these problems in two ways. Either
230 transfer and store numbers always in text format, instead of raw
231 binary, or else consider using modules like Data::Dumper (included in
232 the standard distribution as of Perl 5.005) and Storable (included as
233 of perl 5.8). Keeping all data as text significantly simplifies matters.
235 =head2 Files and Filesystems
237 Most platforms these days structure files in a hierarchical fashion.
238 So, it is reasonably safe to assume that all platforms support the
239 notion of a "path" to uniquely identify a file on the system. How
240 that path is really written, though, differs considerably.
242 Although similar, file path specifications differ between Unix,
243 Windows, S<Mac OS>, OS/2, VMS, VOS, S<RISC OS>, and probably others.
244 Unix, for example, is one of the few OSes that has the elegant idea
245 of a single root directory.
247 DOS, OS/2, VMS, VOS, and Windows can work similarly to Unix with C</>
248 as path separator, or in their own idiosyncratic ways (such as having
249 several root directories and various "unrooted" device files such NIL:
252 S<Mac OS> uses C<:> as a path separator instead of C</>.
254 The filesystem may support neither hard links (C<link>) nor
255 symbolic links (C<symlink>, C<readlink>, C<lstat>).
257 The filesystem may support neither access timestamp nor change
258 timestamp (meaning that about the only portable timestamp is the
259 modification timestamp), or one second granularity of any timestamps
260 (e.g. the FAT filesystem limits the time granularity to two seconds).
262 VOS perl can emulate Unix filenames with C</> as path separator. The
263 native pathname characters greater-than, less-than, number-sign, and
264 percent-sign are always accepted.
266 S<RISC OS> perl can emulate Unix filenames with C</> as path
267 separator, or go native and use C<.> for path separator and C<:> to
268 signal filesystems and disk names.
270 Don't assume UNIX filesystem access semantics: that read, write,
271 and execute are all the permissions there are, and even if they exist,
272 that their semantics (for example what do r, w, and x mean on
273 a directory) are the UNIX ones. The various UNIX/POSIX compatibility
274 layers usually try to make interfaces like chmod() work, but sometimes
275 there simply is no good mapping.
277 If all this is intimidating, have no (well, maybe only a little)
278 fear. There are modules that can help. The File::Spec modules
279 provide methods to do the Right Thing on whatever platform happens
280 to be running the program.
282 use File::Spec::Functions;
283 chdir(updir()); # go up one directory
284 $file = catfile(curdir(), 'temp', 'file.txt');
285 # on Unix and Win32, './temp/file.txt'
286 # on Mac OS, ':temp:file.txt'
287 # on VMS, '[.temp]file.txt'
289 File::Spec is available in the standard distribution as of version
290 5.004_05. File::Spec::Functions is only in File::Spec 0.7 and later,
291 and some versions of perl come with version 0.6. If File::Spec
292 is not updated to 0.7 or later, you must use the object-oriented
293 interface from File::Spec (or upgrade File::Spec).
295 In general, production code should not have file paths hardcoded.
296 Making them user-supplied or read from a configuration file is
297 better, keeping in mind that file path syntax varies on different
300 This is especially noticeable in scripts like Makefiles and test suites,
301 which often assume C</> as a path separator for subdirectories.
303 Also of use is File::Basename from the standard distribution, which
304 splits a pathname into pieces (base filename, full path to directory,
307 Even when on a single platform (if you can call Unix a single platform),
308 remember not to count on the existence or the contents of particular
309 system-specific files or directories, like F</etc/passwd>,
310 F</etc/sendmail.conf>, F</etc/resolv.conf>, or even F</tmp/>. For
311 example, F</etc/passwd> may exist but not contain the encrypted
312 passwords, because the system is using some form of enhanced security.
313 Or it may not contain all the accounts, because the system is using NIS.
314 If code does need to rely on such a file, include a description of the
315 file and its format in the code's documentation, then make it easy for
316 the user to override the default location of the file.
318 Don't assume a text file will end with a newline. They should,
321 Do not have two files or directories of the same name with different
322 case, like F<test.pl> and F<Test.pl>, as many platforms have
323 case-insensitive (or at least case-forgiving) filenames. Also, try
324 not to have non-word characters (except for C<.>) in the names, and
325 keep them to the 8.3 convention, for maximum portability, onerous a
326 burden though this may appear.
328 Likewise, when using the AutoSplit module, try to keep your functions to
329 8.3 naming and case-insensitive conventions; or, at the least,
330 make it so the resulting files have a unique (case-insensitively)
333 Whitespace in filenames is tolerated on most systems, but not all,
334 and even on systems where it might be tolerated, some utilities
335 might become confused by such whitespace.
337 Many systems (DOS, VMS) cannot have more than one C<.> in their filenames.
339 Don't assume C<< > >> won't be the first character of a filename.
340 Always use C<< < >> explicitly to open a file for reading, or even
341 better, use the three-arg version of open, unless you want the user to
342 be able to specify a pipe open.
344 open(FILE, '<', $existing_file) or die $!;
346 If filenames might use strange characters, it is safest to open it
347 with C<sysopen> instead of C<open>. C<open> is magic and can
348 translate characters like C<< > >>, C<< < >>, and C<|>, which may
349 be the wrong thing to do. (Sometimes, though, it's the right thing.)
350 Three-arg open can also help protect against this translation in cases
351 where it is undesirable.
353 Don't use C<:> as a part of a filename since many systems use that for
354 their own semantics (MacOS Classic for separating pathname components,
355 many networking schemes and utilities for separating the nodename and
356 the pathname, and so on). For the same reasons, avoid C<@>, C<;> and
359 The I<portable filename characters> as defined by ANSI C are
361 a b c d e f g h i j k l m n o p q r t u v w x y z
362 A B C D E F G H I J K L M N O P Q R T U V W X Y Z
366 and the "-" shouldn't be the first character. If you want to be
367 hypercorrect, stay within the 8.3 naming convention (all the files and
368 directories have to be unique within one directory if their names are
369 lowercased and truncated to eight characters before the C<.>, if any,
370 and to three characters after the C<.>, if any). (And do not use
371 C<.>s in directory names.)
373 =head2 System Interaction
375 Not all platforms provide a command line. These are usually platforms
376 that rely primarily on a Graphical User Interface (GUI) for user
377 interaction. A program requiring a command line interface might
378 not work everywhere. This is probably for the user of the program
379 to deal with, so don't stay up late worrying about it.
381 Some platforms can't delete or rename files held open by the system.
382 Remember to C<close> files when you are done with them. Don't
383 C<unlink> or C<rename> an open file. Don't C<tie> or C<open> a
384 file already tied or opened; C<untie> or C<close> it first.
386 Don't open the same file more than once at a time for writing, as some
387 operating systems put mandatory locks on such files.
389 Don't assume that write/modify permission on a directory gives the
390 right to add or delete files/directories in that directory. That is
391 filesystem specific: in some filesystems you need write/modify
392 permission also (or even just) in the file/directory itself. In some
393 filesystems (AFS, DFS) the permission to add/delete directory entries
394 is a completely separate permission.
396 Don't assume that a single C<unlink> completely gets rid of the file:
397 some filesystems (most notably the ones in VMS) have versioned
398 filesystems, and unlink() removes only the most recent one (it doesn't
399 remove all the versions because by default the native tools on those
400 platforms remove just the most recent version, too). The portable
401 idiom to remove all the versions of a file is
403 1 while unlink "file";
405 This will terminate if the file is undeleteable for some reason
406 (protected, not there, and so on).
408 Don't count on a specific environment variable existing in C<%ENV>.
409 Don't count on C<%ENV> entries being case-sensitive, or even
410 case-preserving. Don't try to clear %ENV by saying C<%ENV = ();>, or,
411 if you really have to, make it conditional on C<$^O ne 'VMS'> since in
412 VMS the C<%ENV> table is much more than a per-process key-value string
415 Don't count on signals or C<%SIG> for anything.
417 Don't count on filename globbing. Use C<opendir>, C<readdir>, and
420 Don't count on per-program environment variables, or per-program current
423 Don't count on specific values of C<$!>.
425 =head2 Interprocess Communication (IPC)
427 In general, don't directly access the system in code meant to be
428 portable. That means, no C<system>, C<exec>, C<fork>, C<pipe>,
429 C<``>, C<qx//>, C<open> with a C<|>, nor any of the other things
430 that makes being a perl hacker worth being.
432 Commands that launch external processes are generally supported on
433 most platforms (though many of them do not support any type of
434 forking). The problem with using them arises from what you invoke
435 them on. External tools are often named differently on different
436 platforms, may not be available in the same location, might accept
437 different arguments, can behave differently, and often present their
438 results in a platform-dependent way. Thus, you should seldom depend
439 on them to produce consistent results. (Then again, if you're calling
440 I<netstat -a>, you probably don't expect it to run on both Unix and CP/M.)
442 One especially common bit of Perl code is opening a pipe to B<sendmail>:
444 open(MAIL, '|/usr/lib/sendmail -t')
445 or die "cannot fork sendmail: $!";
447 This is fine for systems programming when sendmail is known to be
448 available. But it is not fine for many non-Unix systems, and even
449 some Unix systems that may not have sendmail installed. If a portable
450 solution is needed, see the various distributions on CPAN that deal
451 with it. Mail::Mailer and Mail::Send in the MailTools distribution are
452 commonly used, and provide several mailing methods, including mail,
453 sendmail, and direct SMTP (via Net::SMTP) if a mail transfer agent is
454 not available. Mail::Sendmail is a standalone module that provides
455 simple, platform-independent mailing.
457 The Unix System V IPC (C<msg*(), sem*(), shm*()>) is not available
458 even on all Unix platforms.
460 Do not use either the bare result of C<pack("N", 10, 20, 30, 40)> or
461 bare v-strings (such as C<v10.20.30.40>) to represent IPv4 addresses:
462 both forms just pack the four bytes into network order. That this
463 would be equal to the C language C<in_addr> struct (which is what the
464 socket code internally uses) is not guaranteed. To be portable use
465 the routines of the Socket extension, such as C<inet_aton()>,
466 C<inet_ntoa()>, and C<sockaddr_in()>.
468 The rule of thumb for portable code is: Do it all in portable Perl, or
469 use a module (that may internally implement it with platform-specific
470 code, but expose a common interface).
472 =head2 External Subroutines (XS)
474 XS code can usually be made to work with any platform, but dependent
475 libraries, header files, etc., might not be readily available or
476 portable, or the XS code itself might be platform-specific, just as Perl
477 code might be. If the libraries and headers are portable, then it is
478 normally reasonable to make sure the XS code is portable, too.
480 A different type of portability issue arises when writing XS code:
481 availability of a C compiler on the end-user's system. C brings
482 with it its own portability issues, and writing XS code will expose
483 you to some of those. Writing purely in Perl is an easier way to
486 =head2 Standard Modules
488 In general, the standard modules work across platforms. Notable
489 exceptions are the CPAN module (which currently makes connections to external
490 programs that may not be available), platform-specific modules (like
491 ExtUtils::MM_VMS), and DBM modules.
493 There is no one DBM module available on all platforms.
494 SDBM_File and the others are generally available on all Unix and DOSish
495 ports, but not in MacPerl, where only NBDM_File and DB_File are
498 The good news is that at least some DBM module should be available, and
499 AnyDBM_File will use whichever module it can find. Of course, then
500 the code needs to be fairly strict, dropping to the greatest common
501 factor (e.g., not exceeding 1K for each record), so that it will
502 work with any DBM module. See L<AnyDBM_File> for more details.
506 The system's notion of time of day and calendar date is controlled in
507 widely different ways. Don't assume the timezone is stored in C<$ENV{TZ}>,
508 and even if it is, don't assume that you can control the timezone through
511 Don't assume that the epoch starts at 00:00:00, January 1, 1970,
512 because that is OS- and implementation-specific. It is better to store a date
513 in an unambiguous representation. The ISO-8601 standard defines
514 "YYYY-MM-DD" as the date format. A text representation (like "1987-12-18")
515 can be easily converted into an OS-specific value using a module like
516 Date::Parse. An array of values, such as those returned by
517 C<localtime>, can be converted to an OS-specific representation using
520 When calculating specific times, such as for tests in time or date modules,
521 it may be appropriate to calculate an offset for the epoch.
524 $offset = Time::Local::timegm(0, 0, 0, 1, 0, 70);
526 The value for C<$offset> in Unix will be C<0>, but in Mac OS will be
527 some large number. C<$offset> can then be added to a Unix time value
528 to get what should be the proper value on any system.
530 =head2 Character sets and character encoding
532 Assume very little about character sets.
534 Assume nothing about numerical values (C<ord>, C<chr>) of characters.
535 Do not use explicit code point ranges (like \xHH-\xHH); use for
536 example symbolic character classes like C<[:print:]>.
538 Do not assume that the alphabetic characters are encoded contiguously
539 (in the numeric sense). There may be gaps.
541 Do not assume anything about the ordering of the characters.
542 The lowercase letters may come before or after the uppercase letters;
543 the lowercase and uppercase may be interlaced so that both `a' and `A'
544 come before `b'; the accented and other international characters may
545 be interlaced so that E<auml> comes before `b'.
547 =head2 Internationalisation
549 If you may assume POSIX (a rather large assumption), you may read
550 more about the POSIX locale system from L<perllocale>. The locale
551 system at least attempts to make things a little bit more portable,
552 or at least more convenient and native-friendly for non-English
553 users. The system affects character sets and encoding, and date
554 and time formatting--amongst other things.
556 =head2 System Resources
558 If your code is destined for systems with severely constrained (or
559 missing!) virtual memory systems then you want to be I<especially> mindful
560 of avoiding wasteful constructs such as:
562 # NOTE: this is no longer "bad" in perl5.005
563 for (0..10000000) {} # bad
564 for (my $x = 0; $x <= 10000000; ++$x) {} # good
566 @lines = <VERY_LARGE_FILE>; # bad
568 while (<FILE>) {$file .= $_} # sometimes bad
569 $file = join('', <FILE>); # better
571 The last two constructs may appear unintuitive to most people. The
572 first repeatedly grows a string, whereas the second allocates a
573 large chunk of memory in one go. On some systems, the second is
574 more efficient that the first.
578 Most multi-user platforms provide basic levels of security, usually
579 implemented at the filesystem level. Some, however, do
580 not-- unfortunately. Thus the notion of user id, or "home" directory,
581 or even the state of being logged-in, may be unrecognizable on many
582 platforms. If you write programs that are security-conscious, it
583 is usually best to know what type of system you will be running
584 under so that you can write code explicitly for that platform (or
587 Don't assume the UNIX filesystem access semantics: the operating
588 system or the filesystem may be using some ACL systems, which are
589 richer languages than the usual rwx. Even if the rwx exist,
590 their semantics might be different.
592 (From security viewpoint testing for permissions before attempting to
593 do something is silly anyway: if one tries this, there is potential
594 for race conditions-- someone or something might change the
595 permissions between the permissions check and the actual operation.
596 Just try the operation.)
598 Don't assume the UNIX user and group semantics: especially, don't
599 expect the C<< $< >> and C<< $> >> (or the C<$(> and C<$)>) to work
600 for switching identities (or memberships).
602 Don't assume set-uid and set-gid semantics. (And even if you do,
603 think twice: set-uid and set-gid are a known can of security worms.)
607 For those times when it is necessary to have platform-specific code,
608 consider keeping the platform-specific code in one place, making porting
609 to other platforms easier. Use the Config module and the special
610 variable C<$^O> to differentiate platforms, as described in
613 Be careful in the tests you supply with your module or programs.
614 Module code may be fully portable, but its tests might not be. This
615 often happens when tests spawn off other processes or call external
616 programs to aid in the testing, or when (as noted above) the tests
617 assume certain things about the filesystem and paths. Be careful
618 not to depend on a specific output style for errors, such as when
619 checking C<$!> after a system call. Some platforms expect a certain
620 output format, and perl on those platforms may have been adjusted
621 accordingly. Most specifically, don't anchor a regex when testing
626 Modules uploaded to CPAN are tested by a variety of volunteers on
627 different platforms. These CPAN testers are notified by mail of each
628 new upload, and reply to the list with PASS, FAIL, NA (not applicable to
629 this platform), or UNKNOWN (unknown), along with any relevant notations.
631 The purpose of the testing is twofold: one, to help developers fix any
632 problems in their code that crop up because of lack of testing on other
633 platforms; two, to provide users with information about whether
634 a given module works on a given platform.
638 =item Mailing list: cpan-testers@perl.org
640 =item Testing results: http://testers.cpan.org/
646 As of version 5.002, Perl is built with a C<$^O> variable that
647 indicates the operating system it was built on. This was implemented
648 to help speed up code that would otherwise have to C<use Config>
649 and use the value of C<$Config{osname}>. Of course, to get more
650 detailed information about the system, looking into C<%Config> is
651 certainly recommended.
653 C<%Config> cannot always be trusted, however, because it was built
654 at compile time. If perl was built in one place, then transferred
655 elsewhere, some values may be wrong. The values may even have been
656 edited after the fact.
660 Perl works on a bewildering variety of Unix and Unix-like platforms (see
661 e.g. most of the files in the F<hints/> directory in the source code kit).
662 On most of these systems, the value of C<$^O> (hence C<$Config{'osname'}>,
663 too) is determined either by lowercasing and stripping punctuation from the
664 first field of the string returned by typing C<uname -a> (or a similar command)
665 at the shell prompt or by testing the file system for the presence of
666 uniquely named files such as a kernel or header file. Here, for example,
667 are a few of the more popular Unix flavors:
669 uname $^O $Config{'archname'}
670 --------------------------------------------
672 BSD/OS bsdos i386-bsdos
673 dgux dgux AViiON-dgux
674 DYNIX/ptx dynixptx i386-dynixptx
675 FreeBSD freebsd freebsd-i386
676 Linux linux arm-linux
677 Linux linux i386-linux
678 Linux linux i586-linux
679 Linux linux ppc-linux
680 HP-UX hpux PA-RISC1.1
682 Mac OS X darwin darwin
683 MachTen PPC machten powerpc-machten
685 NeXT 4 next OPENSTEP-Mach
686 openbsd openbsd i386-openbsd
687 OSF1 dec_osf alpha-dec_osf
688 reliantunix-n svr4 RM400-svr4
689 SCO_SV sco_sv i386-sco_sv
690 SINIX-N svr4 RM400-svr4
691 sn4609 unicos CRAY_C90-unicos
692 sn6521 unicosmk t3e-unicosmk
693 sn9617 unicos CRAY_J90-unicos
694 SunOS solaris sun4-solaris
695 SunOS solaris i86pc-solaris
696 SunOS4 sunos sun4-sunos
698 Because the value of C<$Config{archname}> may depend on the
699 hardware architecture, it can vary more than the value of C<$^O>.
701 =head2 DOS and Derivatives
703 Perl has long been ported to Intel-style microcomputers running under
704 systems like PC-DOS, MS-DOS, OS/2, and most Windows platforms you can
705 bring yourself to mention (except for Windows CE, if you count that).
706 Users familiar with I<COMMAND.COM> or I<CMD.EXE> style shells should
707 be aware that each of these file specifications may have subtle
710 $filespec0 = "c:/foo/bar/file.txt";
711 $filespec1 = "c:\\foo\\bar\\file.txt";
712 $filespec2 = 'c:\foo\bar\file.txt';
713 $filespec3 = 'c:\\foo\\bar\\file.txt';
715 System calls accept either C</> or C<\> as the path separator.
716 However, many command-line utilities of DOS vintage treat C</> as
717 the option prefix, so may get confused by filenames containing C</>.
718 Aside from calling any external programs, C</> will work just fine,
719 and probably better, as it is more consistent with popular usage,
720 and avoids the problem of remembering what to backwhack and what
723 The DOS FAT filesystem can accommodate only "8.3" style filenames. Under
724 the "case-insensitive, but case-preserving" HPFS (OS/2) and NTFS (NT)
725 filesystems you may have to be careful about case returned with functions
726 like C<readdir> or used with functions like C<open> or C<opendir>.
728 DOS also treats several filenames as special, such as AUX, PRN,
729 NUL, CON, COM1, LPT1, LPT2, etc. Unfortunately, sometimes these
730 filenames won't even work if you include an explicit directory
731 prefix. It is best to avoid such filenames, if you want your code
732 to be portable to DOS and its derivatives. It's hard to know what
733 these all are, unfortunately.
735 Users of these operating systems may also wish to make use of
736 scripts such as I<pl2bat.bat> or I<pl2cmd> to
737 put wrappers around your scripts.
739 Newline (C<\n>) is translated as C<\015\012> by STDIO when reading from
740 and writing to files (see L<"Newlines">). C<binmode(FILEHANDLE)>
741 will keep C<\n> translated as C<\012> for that filehandle. Since it is a
742 no-op on other systems, C<binmode> should be used for cross-platform code
743 that deals with binary data. That's assuming you realize in advance
744 that your data is in binary. General-purpose programs should
745 often assume nothing about their data.
747 The C<$^O> variable and the C<$Config{archname}> values for various
748 DOSish perls are as follows:
750 OS $^O $Config{archname} ID Version
751 --------------------------------------------------------
755 Windows 3.1 ? ? 0 3 01
756 Windows 95 MSWin32 MSWin32-x86 1 4 00
757 Windows 98 MSWin32 MSWin32-x86 1 4 10
758 Windows ME MSWin32 MSWin32-x86 1 ?
759 Windows NT MSWin32 MSWin32-x86 2 4 xx
760 Windows NT MSWin32 MSWin32-ALPHA 2 4 xx
761 Windows NT MSWin32 MSWin32-ppc 2 4 xx
762 Windows 2000 MSWin32 MSWin32-x86 2 5 xx
763 Windows XP MSWin32 MSWin32-x86 2 ?
764 Windows CE MSWin32 ? 3
767 The various MSWin32 Perl's can distinguish the OS they are running on
768 via the value of the fifth element of the list returned from
769 Win32::GetOSVersion(). For example:
771 if ($^O eq 'MSWin32') {
772 my @os_version_info = Win32::GetOSVersion();
773 print +('3.1','95','NT')[$os_version_info[4]],"\n";
782 The djgpp environment for DOS, http://www.delorie.com/djgpp/
787 The EMX environment for DOS, OS/2, etc. emx@iaehv.nl,
788 http://www.leo.org/pub/comp/os/os2/leo/gnu/emx+gcc/index.html or
789 ftp://hobbes.nmsu.edu/pub/os2/dev/emx. Also L<perlos2>.
793 Build instructions for Win32 in L<perlwin32>, or under the Cygnus environment
798 The C<Win32::*> modules in L<Win32>.
802 The ActiveState Pages, http://www.activestate.com/
806 The Cygwin environment for Win32; F<README.cygwin> (installed
807 as L<perlcygwin>), http://www.cygwin.com/
811 The U/WIN environment for Win32,
812 http://www.research.att.com/sw/tools/uwin/
816 Build instructions for OS/2, L<perlos2>
822 Any module requiring XS compilation is right out for most people, because
823 MacPerl is built using non-free (and non-cheap!) compilers. Some XS
824 modules that can work with MacPerl are built and distributed in binary
827 Directories are specified as:
829 volume:folder:file for absolute pathnames
830 volume:folder: for absolute pathnames
831 :folder:file for relative pathnames
832 :folder: for relative pathnames
833 :file for relative pathnames
834 file for relative pathnames
836 Files are stored in the directory in alphabetical order. Filenames are
837 limited to 31 characters, and may include any character except for
838 null and C<:>, which is reserved as the path separator.
840 Instead of C<flock>, see C<FSpSetFLock> and C<FSpRstFLock> in the
841 Mac::Files module, or C<chmod(0444, ...)> and C<chmod(0666, ...)>.
843 In the MacPerl application, you can't run a program from the command line;
844 programs that expect C<@ARGV> to be populated can be edited with something
845 like the following, which brings up a dialog box asking for the command
849 @ARGV = split /\s+/, MacPerl::Ask('Arguments?');
852 A MacPerl script saved as a "droplet" will populate C<@ARGV> with the full
853 pathnames of the files dropped onto the script.
855 Mac users can run programs under a type of command line interface
856 under MPW (Macintosh Programmer's Workshop, a free development
857 environment from Apple). MacPerl was first introduced as an MPW
858 tool, and MPW can be used like a shell:
860 perl myscript.plx some arguments
862 ToolServer is another app from Apple that provides access to MPW tools
863 from MPW and the MacPerl app, which allows MacPerl programs to use
864 C<system>, backticks, and piped C<open>.
866 "S<Mac OS>" is the proper name for the operating system, but the value
867 in C<$^O> is "MacOS". To determine architecture, version, or whether
868 the application or MPW tool version is running, check:
870 $is_app = $MacPerl::Version =~ /App/;
871 $is_tool = $MacPerl::Version =~ /MPW/;
872 ($version) = $MacPerl::Version =~ /^(\S+)/;
873 $is_ppc = $MacPerl::Architecture eq 'MacPPC';
874 $is_68k = $MacPerl::Architecture eq 'Mac68K';
876 S<Mac OS X>, based on NeXT's OpenStep OS, runs MacPerl natively, under the
877 "Classic" environment. There is no "Carbon" version of MacPerl to run
878 under the primary Mac OS X environment. S<Mac OS X> and its Open Source
879 version, Darwin, both run Unix perl natively.
887 MacPerl Development, http://dev.macperl.org/ .
891 The MacPerl Pages, http://www.macperl.com/ .
895 The MacPerl mailing lists, http://lists.perl.org/ .
901 Perl on VMS is discussed in L<perlvms> in the perl distribution.
902 Perl on VMS can accept either VMS- or Unix-style file
903 specifications as in either of the following:
905 $ perl -ne "print if /perl_setup/i" SYS$LOGIN:LOGIN.COM
906 $ perl -ne "print if /perl_setup/i" /sys$login/login.com
908 but not a mixture of both as in:
910 $ perl -ne "print if /perl_setup/i" sys$login:/login.com
911 Can't open sys$login:/login.com: file specification syntax error
913 Interacting with Perl from the Digital Command Language (DCL) shell
914 often requires a different set of quotation marks than Unix shells do.
917 $ perl -e "print ""Hello, world.\n"""
920 There are several ways to wrap your perl scripts in DCL F<.COM> files, if
921 you are so inclined. For example:
923 $ write sys$output "Hello from DCL!"
925 $ then perl -x 'f$environment("PROCEDURE")
926 $ else perl -x - 'p1 'p2 'p3 'p4 'p5 'p6 'p7 'p8
927 $ deck/dollars="__END__"
930 print "Hello from Perl!\n";
935 Do take care with C<$ ASSIGN/nolog/user SYS$COMMAND: SYS$INPUT> if your
936 perl-in-DCL script expects to do things like C<< $read = <STDIN>; >>.
938 Filenames are in the format "name.extension;version". The maximum
939 length for filenames is 39 characters, and the maximum length for
940 extensions is also 39 characters. Version is a number from 1 to
941 32767. Valid characters are C</[A-Z0-9$_-]/>.
943 VMS's RMS filesystem is case-insensitive and does not preserve case.
944 C<readdir> returns lowercased filenames, but specifying a file for
945 opening remains case-insensitive. Files without extensions have a
946 trailing period on them, so doing a C<readdir> with a file named F<A.;5>
947 will return F<a.> (though that file could be opened with
950 RMS had an eight level limit on directory depths from any rooted logical
951 (allowing 16 levels overall) prior to VMS 7.2. Hence
952 C<PERL_ROOT:[LIB.2.3.4.5.6.7.8]> is a valid directory specification but
953 C<PERL_ROOT:[LIB.2.3.4.5.6.7.8.9]> is not. F<Makefile.PL> authors might
954 have to take this into account, but at least they can refer to the former
955 as C</PERL_ROOT/lib/2/3/4/5/6/7/8/>.
957 The VMS::Filespec module, which gets installed as part of the build
958 process on VMS, is a pure Perl module that can easily be installed on
959 non-VMS platforms and can be helpful for conversions to and from RMS
962 What C<\n> represents depends on the type of file opened. It usually
963 represents C<\012> but it could also be C<\015>, C<\012>, C<\015\012>,
964 C<\000>, C<\040>, or nothing depending on the file organiztion and
965 record format. The VMS::Stdio module provides access to the
966 special fopen() requirements of files with unusual attributes on VMS.
968 TCP/IP stacks are optional on VMS, so socket routines might not be
969 implemented. UDP sockets may not be supported.
971 The value of C<$^O> on OpenVMS is "VMS". To determine the architecture
972 that you are running on without resorting to loading all of C<%Config>
973 you can examine the content of the C<@INC> array like so:
975 if (grep(/VMS_AXP/, @INC)) {
976 print "I'm on Alpha!\n";
978 } elsif (grep(/VMS_VAX/, @INC)) {
979 print "I'm on VAX!\n";
982 print "I'm not so sure about where $^O is...\n";
985 On VMS, perl determines the UTC offset from the C<SYS$TIMEZONE_DIFFERENTIAL>
986 logical name. Although the VMS epoch began at 17-NOV-1858 00:00:00.00,
987 calls to C<localtime> are adjusted to count offsets from
988 01-JAN-1970 00:00:00.00, just like Unix.
996 F<README.vms> (installed as L<README_vms>), L<perlvms>
1000 vmsperl list, majordomo@perl.org
1002 (Put the words C<subscribe vmsperl> in message body.)
1006 vmsperl on the web, http://www.sidhe.org/vmsperl/index.html
1012 Perl on VOS is discussed in F<README.vos> in the perl distribution
1013 (installed as L<perlvos>). Perl on VOS can accept either VOS- or
1014 Unix-style file specifications as in either of the following:
1016 $ perl -ne "print if /perl_setup/i" >system>notices
1017 $ perl -ne "print if /perl_setup/i" /system/notices
1019 or even a mixture of both as in:
1021 $ perl -ne "print if /perl_setup/i" >system/notices
1023 Even though VOS allows the slash character to appear in object
1024 names, because the VOS port of Perl interprets it as a pathname
1025 delimiting character, VOS files, directories, or links whose names
1026 contain a slash character cannot be processed. Such files must be
1027 renamed before they can be processed by Perl. Note that VOS limits
1028 file names to 32 or fewer characters.
1030 See F<README.vos> for restrictions that apply when Perl is built
1031 with the alpha version of VOS POSIX.1 support.
1033 Perl on VOS is built without any extensions and does not support
1036 The value of C<$^O> on VOS is "VOS". To determine the architecture that
1037 you are running on without resorting to loading all of C<%Config> you
1038 can examine the content of the @INC array like so:
1041 print "I'm on a Stratus box!\n";
1043 print "I'm not on a Stratus box!\n";
1047 if (grep(/860/, @INC)) {
1048 print "This box is a Stratus XA/R!\n";
1050 } elsif (grep(/7100/, @INC)) {
1051 print "This box is a Stratus HP 7100 or 8xxx!\n";
1053 } elsif (grep(/8000/, @INC)) {
1054 print "This box is a Stratus HP 8xxx!\n";
1057 print "This box is a Stratus 68K!\n";
1070 The VOS mailing list.
1072 There is no specific mailing list for Perl on VOS. You can post
1073 comments to the comp.sys.stratus newsgroup, or subscribe to the general
1074 Stratus mailing list. Send a letter with "Subscribe Info-Stratus" in
1075 the message body to majordomo@list.stratagy.com.
1079 VOS Perl on the web at http://ftp.stratus.com/pub/vos/vos.html
1083 =head2 EBCDIC Platforms
1085 Recent versions of Perl have been ported to platforms such as OS/400 on
1086 AS/400 minicomputers as well as OS/390, VM/ESA, and BS2000 for S/390
1087 Mainframes. Such computers use EBCDIC character sets internally (usually
1088 Character Code Set ID 0037 for OS/400 and either 1047 or POSIX-BC for S/390
1089 systems). On the mainframe perl currently works under the "Unix system
1090 services for OS/390" (formerly known as OpenEdition), VM/ESA OpenEdition, or
1091 the BS200 POSIX-BC system (BS2000 is supported in perl 5.6 and greater).
1092 See L<perlos390> for details.
1094 As of R2.5 of USS for OS/390 and Version 2.3 of VM/ESA these Unix
1095 sub-systems do not support the C<#!> shebang trick for script invocation.
1096 Hence, on OS/390 and VM/ESA perl scripts can be executed with a header
1097 similar to the following simple script:
1100 eval 'exec /usr/local/bin/perl -S $0 ${1+"$@"}'
1102 #!/usr/local/bin/perl # just a comment really
1104 print "Hello from perl!\n";
1106 OS/390 will support the C<#!> shebang trick in release 2.8 and beyond.
1107 Calls to C<system> and backticks can use POSIX shell syntax on all
1110 On the AS/400, if PERL5 is in your library list, you may need
1111 to wrap your perl scripts in a CL procedure to invoke them like so:
1114 CALL PGM(PERL5/PERL) PARM('/QOpenSys/hello.pl')
1117 This will invoke the perl script F<hello.pl> in the root of the
1118 QOpenSys file system. On the AS/400 calls to C<system> or backticks
1121 On these platforms, bear in mind that the EBCDIC character set may have
1122 an effect on what happens with some perl functions (such as C<chr>,
1123 C<pack>, C<print>, C<printf>, C<ord>, C<sort>, C<sprintf>, C<unpack>), as
1124 well as bit-fiddling with ASCII constants using operators like C<^>, C<&>
1125 and C<|>, not to mention dealing with socket interfaces to ASCII computers
1126 (see L<"Newlines">).
1128 Fortunately, most web servers for the mainframe will correctly
1129 translate the C<\n> in the following statement to its ASCII equivalent
1130 (C<\r> is the same under both Unix and OS/390 & VM/ESA):
1132 print "Content-type: text/html\r\n\r\n";
1134 The values of C<$^O> on some of these platforms includes:
1136 uname $^O $Config{'archname'}
1137 --------------------------------------------
1140 POSIX-BC posix-bc BS2000-posix-bc
1143 Some simple tricks for determining if you are running on an EBCDIC
1144 platform could include any of the following (perhaps all):
1146 if ("\t" eq "\05") { print "EBCDIC may be spoken here!\n"; }
1148 if (ord('A') == 193) { print "EBCDIC may be spoken here!\n"; }
1150 if (chr(169) eq 'z') { print "EBCDIC may be spoken here!\n"; }
1152 One thing you may not want to rely on is the EBCDIC encoding
1153 of punctuation characters since these may differ from code page to code
1154 page (and once your module or script is rumoured to work with EBCDIC,
1155 folks will want it to work with all EBCDIC character sets).
1165 L<perlos390>, F<README.os390>, F<perlbs2000>, F<README.vmesa>,
1170 The perl-mvs@perl.org list is for discussion of porting issues as well as
1171 general usage issues for all EBCDIC Perls. Send a message body of
1172 "subscribe perl-mvs" to majordomo@perl.org.
1176 AS/400 Perl information at
1177 http://as400.rochester.ibm.com/
1178 as well as on CPAN in the F<ports/> directory.
1182 =head2 Acorn RISC OS
1184 Because Acorns use ASCII with newlines (C<\n>) in text files as C<\012> like
1185 Unix, and because Unix filename emulation is turned on by default,
1186 most simple scripts will probably work "out of the box". The native
1187 filesystem is modular, and individual filesystems are free to be
1188 case-sensitive or insensitive, and are usually case-preserving. Some
1189 native filesystems have name length limits, which file and directory
1190 names are silently truncated to fit. Scripts should be aware that the
1191 standard filesystem currently has a name length limit of B<10>
1192 characters, with up to 77 items in a directory, but other filesystems
1193 may not impose such limitations.
1195 Native filenames are of the form
1197 Filesystem#Special_Field::DiskName.$.Directory.Directory.File
1201 Special_Field is not usually present, but may contain . and $ .
1202 Filesystem =~ m|[A-Za-z0-9_]|
1203 DsicName =~ m|[A-Za-z0-9_/]|
1204 $ represents the root directory
1205 . is the path separator
1206 @ is the current directory (per filesystem but machine global)
1207 ^ is the parent directory
1208 Directory and File =~ m|[^\0- "\.\$\%\&:\@\\^\|\177]+|
1210 The default filename translation is roughly C<tr|/.|./|;>
1212 Note that C<"ADFS::HardDisk.$.File" ne 'ADFS::HardDisk.$.File'> and that
1213 the second stage of C<$> interpolation in regular expressions will fall
1214 foul of the C<$.> if scripts are not careful.
1216 Logical paths specified by system variables containing comma-separated
1217 search lists are also allowed; hence C<System:Modules> is a valid
1218 filename, and the filesystem will prefix C<Modules> with each section of
1219 C<System$Path> until a name is made that points to an object on disk.
1220 Writing to a new file C<System:Modules> would be allowed only if
1221 C<System$Path> contains a single item list. The filesystem will also
1222 expand system variables in filenames if enclosed in angle brackets, so
1223 C<< <System$Dir>.Modules >> would look for the file
1224 S<C<$ENV{'System$Dir'} . 'Modules'>>. The obvious implication of this is
1225 that B<fully qualified filenames can start with C<< <> >>> and should
1226 be protected when C<open> is used for input.
1228 Because C<.> was in use as a directory separator and filenames could not
1229 be assumed to be unique after 10 characters, Acorn implemented the C
1230 compiler to strip the trailing C<.c> C<.h> C<.s> and C<.o> suffix from
1231 filenames specified in source code and store the respective files in
1232 subdirectories named after the suffix. Hence files are translated:
1235 C:foo.h C:h.foo (logical path variable)
1236 sys/os.h sys.h.os (C compiler groks Unix-speak)
1237 10charname.c c.10charname
1238 10charname.o o.10charname
1239 11charname_.c c.11charname (assuming filesystem truncates at 10)
1241 The Unix emulation library's translation of filenames to native assumes
1242 that this sort of translation is required, and it allows a user-defined list
1243 of known suffixes that it will transpose in this fashion. This may
1244 seem transparent, but consider that with these rules C<foo/bar/baz.h>
1245 and C<foo/bar/h/baz> both map to C<foo.bar.h.baz>, and that C<readdir> and
1246 C<glob> cannot and do not attempt to emulate the reverse mapping. Other
1247 C<.>'s in filenames are translated to C</>.
1249 As implied above, the environment accessed through C<%ENV> is global, and
1250 the convention is that program specific environment variables are of the
1251 form C<Program$Name>. Each filesystem maintains a current directory,
1252 and the current filesystem's current directory is the B<global> current
1253 directory. Consequently, sociable programs don't change the current
1254 directory but rely on full pathnames, and programs (and Makefiles) cannot
1255 assume that they can spawn a child process which can change the current
1256 directory without affecting its parent (and everyone else for that
1259 Because native operating system filehandles are global and are currently
1260 allocated down from 255, with 0 being a reserved value, the Unix emulation
1261 library emulates Unix filehandles. Consequently, you can't rely on
1262 passing C<STDIN>, C<STDOUT>, or C<STDERR> to your children.
1264 The desire of users to express filenames of the form
1265 C<< <Foo$Dir>.Bar >> on the command line unquoted causes problems,
1266 too: C<``> command output capture has to perform a guessing game. It
1267 assumes that a string C<< <[^<>]+\$[^<>]> >> is a
1268 reference to an environment variable, whereas anything else involving
1269 C<< < >> or C<< > >> is redirection, and generally manages to be 99%
1270 right. Of course, the problem remains that scripts cannot rely on any
1271 Unix tools being available, or that any tools found have Unix-like command
1274 Extensions and XS are, in theory, buildable by anyone using free
1275 tools. In practice, many don't, as users of the Acorn platform are
1276 used to binary distributions. MakeMaker does run, but no available
1277 make currently copes with MakeMaker's makefiles; even if and when
1278 this should be fixed, the lack of a Unix-like shell will cause
1279 problems with makefile rules, especially lines of the form C<cd
1280 sdbm && make all>, and anything using quoting.
1282 "S<RISC OS>" is the proper name for the operating system, but the value
1283 in C<$^O> is "riscos" (because we don't like shouting).
1287 Perl has been ported to many platforms that do not fit into any of
1288 the categories listed above. Some, such as AmigaOS, Atari MiNT,
1289 BeOS, HP MPE/iX, QNX, Plan 9, and VOS, have been well-integrated
1290 into the standard Perl source code kit. You may need to see the
1291 F<ports/> directory on CPAN for information, and possibly binaries,
1292 for the likes of: aos, Atari ST, lynxos, riscos, Novell Netware,
1293 Tandem Guardian, I<etc.> (Yes, we know that some of these OSes may
1294 fall under the Unix category, but we are not a standards body.)
1296 Some approximate operating system names and their C<$^O> values
1297 in the "OTHER" category include:
1299 OS $^O $Config{'archname'}
1300 ------------------------------------------
1301 Amiga DOS amigaos m68k-amigos
1302 MPE/iX mpeix PA-RISC1.1
1310 Amiga, F<README.amiga> (installed as L<perlamiga>).
1314 Atari, F<README.mint> and Guido Flohr's web page
1315 http://stud.uni-sb.de/~gufl0000/
1319 Be OS, F<README.beos>
1323 HP 300 MPE/iX, F<README.mpeix> and Mark Bixby's web page
1324 http://www.bixby.org/mark/perlix.html
1328 A free perl5-based PERL.NLM for Novell Netware is available in
1329 precompiled binary and source code form from http://www.novell.com/
1330 as well as from CPAN.
1334 Plan 9, F<README.plan9>
1338 =head1 FUNCTION IMPLEMENTATIONS
1340 Listed below are functions that are either completely unimplemented
1341 or else have been implemented differently on various platforms.
1342 Following each description will be, in parentheses, a list of
1343 platforms that the description applies to.
1345 The list may well be incomplete, or even wrong in some places. When
1346 in doubt, consult the platform-specific README files in the Perl
1347 source distribution, and any other documentation resources accompanying
1350 Be aware, moreover, that even among Unix-ish systems there are variations.
1352 For many functions, you can also query C<%Config>, exported by
1353 default from the Config module. For example, to check whether the
1354 platform has the C<lstat> call, check C<$Config{d_lstat}>. See
1355 L<Config> for a full description of available variables.
1357 =head2 Alphabetical Listing of Perl Functions
1367 C<-r>, C<-w>, and C<-x> have a limited meaning only; directories
1368 and applications are executable, and there are no uid/gid
1369 considerations. C<-o> is not supported. (S<Mac OS>)
1371 C<-r>, C<-w>, C<-x>, and C<-o> tell whether the file is accessible,
1372 which may not reflect UIC-based file protections. (VMS)
1374 C<-s> returns the size of the data fork, not the total size of data fork
1375 plus resource fork. (S<Mac OS>).
1377 C<-s> by name on an open file will return the space reserved on disk,
1378 rather than the current extent. C<-s> on an open filehandle returns the
1379 current size. (S<RISC OS>)
1381 C<-R>, C<-W>, C<-X>, C<-O> are indistinguishable from C<-r>, C<-w>,
1382 C<-x>, C<-o>. (S<Mac OS>, Win32, VMS, S<RISC OS>)
1384 C<-b>, C<-c>, C<-k>, C<-g>, C<-p>, C<-u>, C<-A> are not implemented.
1387 C<-g>, C<-k>, C<-l>, C<-p>, C<-u>, C<-A> are not particularly meaningful.
1388 (Win32, VMS, S<RISC OS>)
1390 C<-d> is true if passed a device spec without an explicit directory.
1393 C<-T> and C<-B> are implemented, but might misclassify Mac text files
1394 with foreign characters; this is the case will all platforms, but may
1395 affect S<Mac OS> often. (S<Mac OS>)
1397 C<-x> (or C<-X>) determine if a file ends in one of the executable
1398 suffixes. C<-S> is meaningless. (Win32)
1400 C<-x> (or C<-X>) determine if a file has an executable file type.
1407 Not implemented. (Win32)
1409 =item binmode FILEHANDLE
1411 Meaningless. (S<Mac OS>, S<RISC OS>)
1413 Reopens file and restores pointer; if function fails, underlying
1414 filehandle may be closed, or pointer may be in a different position.
1417 The value returned by C<tell> may be affected after the call, and
1418 the filehandle may be flushed. (Win32)
1422 Only limited meaning. Disabling/enabling write permission is mapped to
1423 locking/unlocking the file. (S<Mac OS>)
1425 Only good for changing "owner" read-write access, "group", and "other"
1426 bits are meaningless. (Win32)
1428 Only good for changing "owner" and "other" read-write access. (S<RISC OS>)
1430 Access permissions are mapped onto VOS access-control list changes. (VOS)
1434 Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>, VOS)
1436 Does nothing, but won't fail. (Win32)
1438 =item chroot FILENAME
1442 Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>, VOS, VM/ESA)
1444 =item crypt PLAINTEXT,SALT
1446 May not be available if library or source was not provided when building
1449 Not implemented. (VOS)
1453 Not implemented. (VMS, Plan9, VOS)
1455 =item dbmopen HASH,DBNAME,MODE
1457 Not implemented. (VMS, Plan9, VOS)
1461 Not useful. (S<Mac OS>, S<RISC OS>)
1463 Not implemented. (Win32)
1465 Invokes VMS debugger. (VMS)
1469 Not implemented. (S<Mac OS>)
1471 Implemented via Spawn. (VM/ESA)
1473 Does not automatically flush output handles on some platforms.
1474 (SunOS, Solaris, HP-UX)
1480 Emulates UNIX exit() (which considers C<exit 1> to indicate an error) by
1481 mapping the C<1> to SS$_ABORT (C<44>). This behavior may be overridden
1482 with the pragma C<use vmsish 'exit'>. As with the CRTL's exit()
1483 function, C<exit 0> is also mapped to an exit status of SS$_NORMAL
1484 (C<1>); this mapping cannot be overridden. Any other argument to exit()
1485 is used directly as Perl's exit status. (VMS)
1487 =item fcntl FILEHANDLE,FUNCTION,SCALAR
1489 Not implemented. (Win32, VMS)
1491 =item flock FILEHANDLE,OPERATION
1493 Not implemented (S<Mac OS>, VMS, S<RISC OS>, VOS).
1495 Available only on Windows NT (not on Windows 95). (Win32)
1499 Not implemented. (S<Mac OS>, AmigaOS, S<RISC OS>, VOS, VM/ESA)
1501 Emulated using multiple interpreters. See L<perlfork>. (Win32)
1503 Does not automatically flush output handles on some platforms.
1504 (SunOS, Solaris, HP-UX)
1508 Not implemented. (S<Mac OS>, S<RISC OS>)
1512 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
1516 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
1518 =item getpriority WHICH,WHO
1520 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
1524 Not implemented. (S<Mac OS>, Win32)
1526 Not useful. (S<RISC OS>)
1530 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
1532 =item getnetbyname NAME
1534 Not implemented. (S<Mac OS>, Win32, Plan9)
1538 Not implemented. (S<Mac OS>, Win32)
1540 Not useful. (S<RISC OS>)
1544 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
1546 =item getnetbyaddr ADDR,ADDRTYPE
1548 Not implemented. (S<Mac OS>, Win32, Plan9)
1550 =item getprotobynumber NUMBER
1552 Not implemented. (S<Mac OS>)
1554 =item getservbyport PORT,PROTO
1556 Not implemented. (S<Mac OS>)
1560 Not implemented. (S<Mac OS>, Win32, VM/ESA)
1564 Not implemented. (S<Mac OS>, Win32, VMS, VM/ESA)
1568 Not implemented. (S<Mac OS>, Win32)
1572 Not implemented. (S<Mac OS>, Win32, Plan9)
1576 Not implemented. (S<Mac OS>, Win32, Plan9)
1580 Not implemented. (Win32, Plan9)
1584 Not implemented. (S<Mac OS>, Win32, S<RISC OS>)
1588 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
1590 =item sethostent STAYOPEN
1592 Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>)
1594 =item setnetent STAYOPEN
1596 Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>)
1598 =item setprotoent STAYOPEN
1600 Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>)
1602 =item setservent STAYOPEN
1604 Not implemented. (Plan9, Win32, S<RISC OS>)
1608 Not implemented. (S<Mac OS>, MPE/iX, VM/ESA, Win32)
1612 Not implemented. (S<Mac OS>, MPE/iX, S<RISC OS>, VM/ESA, VMS, Win32)
1616 Not implemented. (S<Mac OS>, Win32)
1620 Not implemented. (S<Mac OS>, Win32, Plan9)
1624 Not implemented. (S<Mac OS>, Win32, Plan9)
1628 Not implemented. (Plan9, Win32)
1630 =item getsockopt SOCKET,LEVEL,OPTNAME
1632 Not implemented. (Plan9)
1638 This operator is implemented via the File::Glob extension on most
1639 platforms. See L<File::Glob> for portability information.
1641 =item ioctl FILEHANDLE,FUNCTION,SCALAR
1643 Not implemented. (VMS)
1645 Available only for socket handles, and it does what the ioctlsocket() call
1646 in the Winsock API does. (Win32)
1648 Available only for socket handles. (S<RISC OS>)
1650 =item kill SIGNAL, LIST
1652 C<kill(0, LIST)> is implemented for the sake of taint checking;
1653 use with other signals is unimplemented. (S<Mac OS>)
1655 Not implemented, hence not useful for taint checking. (S<RISC OS>)
1657 C<kill()> doesn't have the semantics of C<raise()>, i.e. it doesn't send
1658 a signal to the identified process like it does on Unix platforms.
1659 Instead C<kill($sig, $pid)> terminates the process identified by $pid,
1660 and makes it exit immediately with exit status $sig. As in Unix, if
1661 $sig is 0 and the specified process exists, it returns true without
1662 actually terminating it. (Win32)
1664 =item link OLDFILE,NEWFILE
1666 Not implemented. (S<Mac OS>, MPE/iX, VMS, S<RISC OS>)
1668 Link count not updated because hard links are not quite that hard
1669 (They are sort of half-way between hard and soft links). (AmigaOS)
1671 Hard links are implemented on Win32 (Windows NT and Windows 2000)
1674 =item lstat FILEHANDLE
1680 Not implemented. (VMS, S<RISC OS>)
1682 Return values (especially for device and inode) may be bogus. (Win32)
1684 =item msgctl ID,CMD,ARG
1686 =item msgget KEY,FLAGS
1688 =item msgsnd ID,MSG,FLAGS
1690 =item msgrcv ID,VAR,SIZE,TYPE,FLAGS
1692 Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>, VOS)
1694 =item open FILEHANDLE,EXPR
1696 =item open FILEHANDLE
1698 The C<|> variants are supported only if ToolServer is installed.
1701 open to C<|-> and C<-|> are unsupported. (S<Mac OS>, Win32, S<RISC OS>)
1703 Opening a process does not automatically flush output handles on some
1704 platforms. (SunOS, Solaris, HP-UX)
1706 =item pipe READHANDLE,WRITEHANDLE
1708 Very limited functionality. (MiNT)
1714 Not implemented. (Win32, VMS, S<RISC OS>)
1716 =item select RBITS,WBITS,EBITS,TIMEOUT
1718 Only implemented on sockets. (Win32, VMS)
1720 Only reliable on sockets. (S<RISC OS>)
1722 Note that the C<select FILEHANDLE> form is generally portable.
1724 =item semctl ID,SEMNUM,CMD,ARG
1726 =item semget KEY,NSEMS,FLAGS
1728 =item semop KEY,OPSTRING
1730 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
1734 Not implemented. (MPE/iX, Win32)
1736 =item setpgrp PID,PGRP
1738 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
1740 =item setpriority WHICH,WHO,PRIORITY
1742 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
1746 Not implemented. (MPE/iX, Win32)
1748 =item setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL
1750 Not implemented. (Plan9)
1752 =item shmctl ID,CMD,ARG
1754 =item shmget KEY,SIZE,FLAGS
1756 =item shmread ID,VAR,POS,SIZE
1758 =item shmwrite ID,STRING,POS,SIZE
1760 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
1762 =item sockatmark SOCKET
1764 A relatively recent addition to socket functions, may not
1765 be implemented even in UNIX platforms.
1767 =item socketpair SOCKET1,SOCKET2,DOMAIN,TYPE,PROTOCOL
1769 Not implemented. (Win32, VMS, S<RISC OS>, VOS, VM/ESA)
1771 =item stat FILEHANDLE
1777 Platforms that do not have rdev, blksize, or blocks will return these
1778 as '', so numeric comparison or manipulation of these fields may cause
1779 'not numeric' warnings.
1781 mtime and atime are the same thing, and ctime is creation time instead of
1782 inode change time. (S<Mac OS>)
1784 device and inode are not meaningful. (Win32)
1786 device and inode are not necessarily reliable. (VMS)
1788 mtime, atime and ctime all return the last modification time. Device and
1789 inode are not necessarily reliable. (S<RISC OS>)
1791 dev, rdev, blksize, and blocks are not available. inode is not
1792 meaningful and will differ between stat calls on the same file. (os2)
1794 some versions of cygwin when doing a stat("foo") and if not finding it
1795 may then attempt to stat("foo.exe") (Cygwin)
1797 =item symlink OLDFILE,NEWFILE
1799 Not implemented. (Win32, VMS, S<RISC OS>)
1803 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
1805 =item sysopen FILEHANDLE,FILENAME,MODE,PERMS
1807 The traditional "0", "1", and "2" MODEs are implemented with different
1808 numeric values on some systems. The flags exported by C<Fcntl>
1809 (O_RDONLY, O_WRONLY, O_RDWR) should work everywhere though. (S<Mac
1810 OS>, OS/390, VM/ESA)
1814 In general, do not assume the UNIX/POSIX semantics that you can shift
1815 C<$?> right by eight to get the exit value, or that C<$? & 127>
1816 would give you the number of the signal that terminated the program,
1817 or that C<$? & 128> would test true if the program was terminated by a
1818 coredump. Instead, use the POSIX W*() interfaces: for example, use
1819 WIFEXITED($?) an WEXITVALUE($?) to test for a normal exit and the exit
1820 value, and WIFSIGNALED($?) and WTERMSIG($?) for a signal exit and the
1821 signal. Core dumping is not a portable concept, so there's no portable
1822 way to test for that.
1824 Only implemented if ToolServer is installed. (S<Mac OS>)
1826 As an optimization, may not call the command shell specified in
1827 C<$ENV{PERL5SHELL}>. C<system(1, @args)> spawns an external
1828 process and immediately returns its process designator, without
1829 waiting for it to terminate. Return value may be used subsequently
1830 in C<wait> or C<waitpid>. Failure to spawn() a subprocess is indicated
1831 by setting $? to "255 << 8". C<$?> is set in a way compatible with
1832 Unix (i.e. the exitstatus of the subprocess is obtained by "$? >> 8",
1833 as described in the documentation). (Win32)
1835 There is no shell to process metacharacters, and the native standard is
1836 to pass a command line terminated by "\n" "\r" or "\0" to the spawned
1837 program. Redirection such as C<< > foo >> is performed (if at all) by
1838 the run time library of the spawned program. C<system> I<list> will call
1839 the Unix emulation library's C<exec> emulation, which attempts to provide
1840 emulation of the stdin, stdout, stderr in force in the parent, providing
1841 the child program uses a compatible version of the emulation library.
1842 I<scalar> will call the native command line direct and no such emulation
1843 of a child Unix program will exists. Mileage B<will> vary. (S<RISC OS>)
1845 Far from being POSIX compliant. Because there may be no underlying
1846 /bin/sh tries to work around the problem by forking and execing the
1847 first token in its argument string. Handles basic redirection
1848 ("<" or ">") on its own behalf. (MiNT)
1850 Does not automatically flush output handles on some platforms.
1851 (SunOS, Solaris, HP-UX)
1853 The return value is POSIX-like (shifted up by 8 bits), which only allows
1854 room for a made-up value derived from the severity bits of the native
1855 32-bit condition code (unless overridden by C<use vmsish 'status'>).
1856 For more details see L<perlvms/$?>. (VMS)
1860 Only the first entry returned is nonzero. (S<Mac OS>)
1862 "cumulative" times will be bogus. On anything other than Windows NT
1863 or Windows 2000, "system" time will be bogus, and "user" time is
1864 actually the time returned by the clock() function in the C runtime
1867 Not useful. (S<RISC OS>)
1869 =item truncate FILEHANDLE,LENGTH
1871 =item truncate EXPR,LENGTH
1873 Not implemented. (Older versions of VMS)
1875 Truncation to zero-length only. (VOS)
1877 If a FILEHANDLE is supplied, it must be writable and opened in append
1878 mode (i.e., use C<<< open(FH, '>>filename') >>>
1879 or C<sysopen(FH,...,O_APPEND|O_RDWR)>. If a filename is supplied, it
1880 should not be held open elsewhere. (Win32)
1886 Returns undef where unavailable, as of version 5.005.
1888 C<umask> works but the correct permissions are set only when the file
1889 is finally closed. (AmigaOS)
1893 Only the modification time is updated. (S<BeOS>, S<Mac OS>, VMS, S<RISC OS>)
1895 May not behave as expected. Behavior depends on the C runtime
1896 library's implementation of utime(), and the filesystem being
1897 used. The FAT filesystem typically does not support an "access
1898 time" field, and it may limit timestamps to a granularity of
1899 two seconds. (Win32)
1903 =item waitpid PID,FLAGS
1905 Not implemented. (S<Mac OS>, VOS)
1907 Can only be applied to process handles returned for processes spawned
1908 using C<system(1, ...)> or pseudo processes created with C<fork()>. (Win32)
1910 Not useful. (S<RISC OS>)
1918 =item v1.48, 02 February 2001
1920 Various updates from perl5-porters over the past year, supported
1921 platforms update from Jarkko Hietaniemi.
1923 =item v1.47, 22 March 2000
1925 Various cleanups from Tom Christiansen, including migration of
1926 long platform listings from L<perl>.
1928 =item v1.46, 12 February 2000
1930 Updates for VOS and MPE/iX. (Peter Prymmer) Other small changes.
1932 =item v1.45, 20 December 1999
1934 Small changes from 5.005_63 distribution, more changes to EBCDIC info.
1936 =item v1.44, 19 July 1999
1938 A bunch of updates from Peter Prymmer for C<$^O> values,
1939 endianness, File::Spec, VMS, BS2000, OS/400.
1941 =item v1.43, 24 May 1999
1943 Added a lot of cleaning up from Tom Christiansen.
1945 =item v1.42, 22 May 1999
1947 Added notes about tests, sprintf/printf, and epoch offsets.
1949 =item v1.41, 19 May 1999
1951 Lots more little changes to formatting and content.
1953 Added a bunch of C<$^O> and related values
1954 for various platforms; fixed mail and web addresses, and added
1955 and changed miscellaneous notes. (Peter Prymmer)
1957 =item v1.40, 11 April 1999
1959 Miscellaneous changes.
1961 =item v1.39, 11 February 1999
1963 Changes from Jarkko and EMX URL fixes Michael Schwern. Additional
1964 note about newlines added.
1966 =item v1.38, 31 December 1998
1968 More changes from Jarkko.
1970 =item v1.37, 19 December 1998
1972 More minor changes. Merge two separate version 1.35 documents.
1974 =item v1.36, 9 September 1998
1976 Updated for Stratus VOS. Also known as version 1.35.
1978 =item v1.35, 13 August 1998
1980 Integrate more minor changes, plus addition of new sections under
1981 L<"ISSUES">: L<"Numbers endianness and Width">,
1982 L<"Character sets and character encoding">,
1983 L<"Internationalisation">.
1985 =item v1.33, 06 August 1998
1987 Integrate more minor changes.
1989 =item v1.32, 05 August 1998
1991 Integrate more minor changes.
1993 =item v1.30, 03 August 1998
1995 Major update for RISC OS, other minor changes.
1997 =item v1.23, 10 July 1998
1999 First public release with perl5.005.
2003 =head1 Supported Platforms
2005 As of early 2001 (the Perl releases 5.6.1 and 5.7.1), the following
2006 platforms are able to build Perl from the standard source code
2007 distribution available at http://www.cpan.org/src/index.html
2030 Tru64 UNIX (DEC OSF/1, Digital UNIX)
2036 1) in DOS mode either the DOS or OS/2 ports can be used
2037 2) Mac OS Classic (pre-X) is almost 5.6.1-ready; building from
2038 the source does work with 5.6.1, but additional MacOS specific
2039 source code is needed for a complete build. See the web
2040 site http://dev.macperl.org/ for more information.
2041 3) compilers: Borland, Cygwin, Mingw32 EGCS/GCC, VC++
2043 The following platforms worked for the previous releases (5.6.0 and 5.7.0),
2044 but we did not manage to test these in time for the 5.7.1 release.
2045 There is a very good chance that these will work fine with the 5.7.1.
2063 The following platform worked for the 5.005_03 major release but not
2064 for 5.6.0. Standardization on UTF-8 as the internal string
2065 representation in 5.6.0 and 5.6.1 introduced incompatibilities in this
2066 EBCDIC platform. While Perl 5.7.1 will build on this platform some
2067 regression tests may fail and the C<use utf8;> pragma typically
2068 introduces text handling errors.
2072 1) previously known as MVS, about to become z/OS.
2074 Strongly related to the OS/390 platform by also being EBCDIC-based
2075 mainframe platforms are the following platforms:
2080 These are also expected to work, albeit with no UTF-8 support, under 5.6.1
2081 for the same reasons as OS/390. Contact the mailing list perl-mvs@perl.org
2084 The following platforms have been known to build Perl from source in
2085 the past (5.005_03 and earlier), but we haven't been able to verify
2086 their status for the current release, either because the
2087 hardware/software platforms are rare or because we don't have an
2088 active champion on these platforms--or both. They used to work,
2089 though, so go ahead and try compiling them, and let perlbug@perl.org
2128 Support for the following platform is planned for a future Perl release:
2132 The following platforms have their own source code distributions and
2133 binaries available via http://www.cpan.org/ports/index.html:
2139 Tandem Guardian 5.004
2141 The following platforms have only binaries available via
2142 http://www.cpan.org/ports/index.html :
2146 Acorn RISCOS 5.005_02
2150 Although we do suggest that you always build your own Perl from
2151 the source code, both for maximal configurability and for security,
2152 in case you are in a hurry you can check
2153 http://www.cpan.org/ports/index.html for binary distributions.
2157 L<perlaix>, L<perlapollo>, L<perlamiga>, L<perlbeos>, L<perlbs200>,
2158 L<perlce>, L<perlcygwin>, L<perldgux>, L<perldos>, L<perlepoc>, L<perlebcdic>,
2159 L<perlhurd>, L<perlhpux>, L<perlmachten>, L<perlmacos>, L<perlmint>,
2160 L<perlmpeix>, L<perlnetware>, L<perlos2>, L<perlos390>, L<perlplan9>,
2161 L<perlqnx>, L<perlsolaris>, L<perltru64>, L<perlunicode>,
2162 L<perlvmesa>, L<perlvms>, L<perlvos>, L<perlwin32>, and L<Win32>.
2164 =head1 AUTHORS / CONTRIBUTORS
2166 Abigail <abigail@foad.org>,
2167 Charles Bailey <bailey@newman.upenn.edu>,
2168 Graham Barr <gbarr@pobox.com>,
2169 Tom Christiansen <tchrist@perl.com>,
2170 Nicholas Clark <nick@ccl4.org>,
2171 Thomas Dorner <Thomas.Dorner@start.de>,
2172 Andy Dougherty <doughera@lafayette.edu>,
2173 Dominic Dunlop <domo@computer.org>,
2174 Neale Ferguson <neale@vma.tabnsw.com.au>,
2175 David J. Fiander <davidf@mks.com>,
2176 Paul Green <Paul_Green@stratus.com>,
2177 M.J.T. Guy <mjtg@cam.ac.uk>,
2178 Jarkko Hietaniemi <jhi@iki.fi>,
2179 Luther Huffman <lutherh@stratcom.com>,
2180 Nick Ing-Simmons <nick@ing-simmons.net>,
2181 Andreas J. KE<ouml>nig <a.koenig@mind.de>,
2182 Markus Laker <mlaker@contax.co.uk>,
2183 Andrew M. Langmead <aml@world.std.com>,
2184 Larry Moore <ljmoore@freespace.net>,
2185 Paul Moore <Paul.Moore@uk.origin-it.com>,
2186 Chris Nandor <pudge@pobox.com>,
2187 Matthias Neeracher <neeri@iis.ee.ethz.ch>,
2188 Philip Newton <pne@cpan.org>,
2189 Gary Ng <71564.1743@CompuServe.COM>,
2190 Tom Phoenix <rootbeer@teleport.com>,
2191 AndrE<eacute> Pirard <A.Pirard@ulg.ac.be>,
2192 Peter Prymmer <pvhp@forte.com>,
2193 Hugo van der Sanden <hv@crypt0.demon.co.uk>,
2194 Gurusamy Sarathy <gsar@activestate.com>,
2195 Paul J. Schinder <schinder@pobox.com>,
2196 Michael G Schwern <schwern@pobox.com>,
2197 Dan Sugalski <dan@sidhe.org>,
2198 Nathan Torkington <gnat@frii.com>.
2202 Version 1.50, last modified 10 Jul 2001