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).
358 The I<portable filename characters> as defined by ANSI C are
360 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
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
365 and the "-" shouldn't be the first character.
367 =head2 System Interaction
369 Not all platforms provide a command line. These are usually platforms
370 that rely primarily on a Graphical User Interface (GUI) for user
371 interaction. A program requiring a command line interface might
372 not work everywhere. This is probably for the user of the program
373 to deal with, so don't stay up late worrying about it.
375 Some platforms can't delete or rename files held open by the system.
376 Remember to C<close> files when you are done with them. Don't
377 C<unlink> or C<rename> an open file. Don't C<tie> or C<open> a
378 file already tied or opened; C<untie> or C<close> it first.
380 Don't open the same file more than once at a time for writing, as some
381 operating systems put mandatory locks on such files.
383 Don't assume that write/modify permission on a directory gives the
384 right to add or delete files/directories in that directory. That is
385 filesystem specific: in some filesystems you need write/modify
386 permission also (or even just) in the file/directory itself. In some
387 filesystems (AFS, DFS) the permission to add/delete directory entries
388 is a completely separate permission.
390 Don't assume that a single C<unlink> completely gets rid of the file:
391 some filesystems (most notably the ones in VMS) have versioned
392 filesystems, and unlink() removes only the most recent one (it doesn't
393 remove all the versions because by default the native tools on those
394 platforms remove just the most recent version, too). The portable
395 idiom to remove all the versions of a file is
397 1 while unlink "file";
399 This will terminate if the file is undeleteable for some reason
400 (protected, not there, and so on).
402 Don't count on a specific environment variable existing in C<%ENV>.
403 Don't count on C<%ENV> entries being case-sensitive, or even
404 case-preserving. Don't try to clear %ENV by saying C<%ENV = ();>, or,
405 if you really have to, make it conditional on C<$^O ne 'VMS'> since in
406 VMS the C<%ENV> table is much more than a per-process key-value string
409 Don't count on signals or C<%SIG> for anything.
411 Don't count on filename globbing. Use C<opendir>, C<readdir>, and
414 Don't count on per-program environment variables, or per-program current
417 Don't count on specific values of C<$!>.
419 =head2 Interprocess Communication (IPC)
421 In general, don't directly access the system in code meant to be
422 portable. That means, no C<system>, C<exec>, C<fork>, C<pipe>,
423 C<``>, C<qx//>, C<open> with a C<|>, nor any of the other things
424 that makes being a perl hacker worth being.
426 Commands that launch external processes are generally supported on
427 most platforms (though many of them do not support any type of
428 forking). The problem with using them arises from what you invoke
429 them on. External tools are often named differently on different
430 platforms, may not be available in the same location, might accept
431 different arguments, can behave differently, and often present their
432 results in a platform-dependent way. Thus, you should seldom depend
433 on them to produce consistent results. (Then again, if you're calling
434 I<netstat -a>, you probably don't expect it to run on both Unix and CP/M.)
436 One especially common bit of Perl code is opening a pipe to B<sendmail>:
438 open(MAIL, '|/usr/lib/sendmail -t')
439 or die "cannot fork sendmail: $!";
441 This is fine for systems programming when sendmail is known to be
442 available. But it is not fine for many non-Unix systems, and even
443 some Unix systems that may not have sendmail installed. If a portable
444 solution is needed, see the various distributions on CPAN that deal
445 with it. Mail::Mailer and Mail::Send in the MailTools distribution are
446 commonly used, and provide several mailing methods, including mail,
447 sendmail, and direct SMTP (via Net::SMTP) if a mail transfer agent is
448 not available. Mail::Sendmail is a standalone module that provides
449 simple, platform-independent mailing.
451 The Unix System V IPC (C<msg*(), sem*(), shm*()>) is not available
452 even on all Unix platforms.
454 Do not use either the bare result of C<pack("N", 10, 20, 30, 40)> or
455 bare v-strings (such as C<v10.20.30.40>) to represent IPv4 addresses:
456 both forms just pack the four bytes into network order. That this
457 would be equal to the C language C<in_addr> struct (which is what the
458 socket code internally uses) is not guaranteed. To be portable use
459 the routines of the Socket extension, such as C<inet_aton()>,
460 C<inet_ntoa()>, and C<sockaddr_in()>.
462 The rule of thumb for portable code is: Do it all in portable Perl, or
463 use a module (that may internally implement it with platform-specific
464 code, but expose a common interface).
466 =head2 External Subroutines (XS)
468 XS code can usually be made to work with any platform, but dependent
469 libraries, header files, etc., might not be readily available or
470 portable, or the XS code itself might be platform-specific, just as Perl
471 code might be. If the libraries and headers are portable, then it is
472 normally reasonable to make sure the XS code is portable, too.
474 A different type of portability issue arises when writing XS code:
475 availability of a C compiler on the end-user's system. C brings
476 with it its own portability issues, and writing XS code will expose
477 you to some of those. Writing purely in Perl is an easier way to
480 =head2 Standard Modules
482 In general, the standard modules work across platforms. Notable
483 exceptions are the CPAN module (which currently makes connections to external
484 programs that may not be available), platform-specific modules (like
485 ExtUtils::MM_VMS), and DBM modules.
487 There is no one DBM module available on all platforms.
488 SDBM_File and the others are generally available on all Unix and DOSish
489 ports, but not in MacPerl, where only NBDM_File and DB_File are
492 The good news is that at least some DBM module should be available, and
493 AnyDBM_File will use whichever module it can find. Of course, then
494 the code needs to be fairly strict, dropping to the greatest common
495 factor (e.g., not exceeding 1K for each record), so that it will
496 work with any DBM module. See L<AnyDBM_File> for more details.
500 The system's notion of time of day and calendar date is controlled in
501 widely different ways. Don't assume the timezone is stored in C<$ENV{TZ}>,
502 and even if it is, don't assume that you can control the timezone through
505 Don't assume that the epoch starts at 00:00:00, January 1, 1970,
506 because that is OS- and implementation-specific. It is better to store a date
507 in an unambiguous representation. The ISO-8601 standard defines
508 "YYYY-MM-DD" as the date format. A text representation (like "1987-12-18")
509 can be easily converted into an OS-specific value using a module like
510 Date::Parse. An array of values, such as those returned by
511 C<localtime>, can be converted to an OS-specific representation using
514 When calculating specific times, such as for tests in time or date modules,
515 it may be appropriate to calculate an offset for the epoch.
518 $offset = Time::Local::timegm(0, 0, 0, 1, 0, 70);
520 The value for C<$offset> in Unix will be C<0>, but in Mac OS will be
521 some large number. C<$offset> can then be added to a Unix time value
522 to get what should be the proper value on any system.
524 =head2 Character sets and character encoding
526 Assume very little about character sets.
528 Assume nothing about numerical values (C<ord>, C<chr>) of characters.
529 Do not use explicit code point ranges (like \xHH-\xHH); use for
530 example symbolic character classes like C<[:print:]>.
532 Do not assume that the alphabetic characters are encoded contiguously
533 (in the numeric sense). There may be gaps.
535 Do not assume anything about the ordering of the characters.
536 The lowercase letters may come before or after the uppercase letters;
537 the lowercase and uppercase may be interlaced so that both `a' and `A'
538 come before `b'; the accented and other international characters may
539 be interlaced so that E<auml> comes before `b'.
541 =head2 Internationalisation
543 If you may assume POSIX (a rather large assumption), you may read
544 more about the POSIX locale system from L<perllocale>. The locale
545 system at least attempts to make things a little bit more portable,
546 or at least more convenient and native-friendly for non-English
547 users. The system affects character sets and encoding, and date
548 and time formatting--amongst other things.
550 =head2 System Resources
552 If your code is destined for systems with severely constrained (or
553 missing!) virtual memory systems then you want to be I<especially> mindful
554 of avoiding wasteful constructs such as:
556 # NOTE: this is no longer "bad" in perl5.005
557 for (0..10000000) {} # bad
558 for (my $x = 0; $x <= 10000000; ++$x) {} # good
560 @lines = <VERY_LARGE_FILE>; # bad
562 while (<FILE>) {$file .= $_} # sometimes bad
563 $file = join('', <FILE>); # better
565 The last two constructs may appear unintuitive to most people. The
566 first repeatedly grows a string, whereas the second allocates a
567 large chunk of memory in one go. On some systems, the second is
568 more efficient that the first.
572 Most multi-user platforms provide basic levels of security, usually
573 implemented at the filesystem level. Some, however, do
574 not-- unfortunately. Thus the notion of user id, or "home" directory,
575 or even the state of being logged-in, may be unrecognizable on many
576 platforms. If you write programs that are security-conscious, it
577 is usually best to know what type of system you will be running
578 under so that you can write code explicitly for that platform (or
581 Don't assume the UNIX filesystem access semantics: the operating
582 system or the filesystem may be using some ACL systems, which are
583 richer languages than the usual rwx. Even if the rwx exist,
584 their semantics might be different.
586 (From security viewpoint testing for permissions before attempting to
587 do something is silly anyway: if one tries this, there is potential
588 for race conditions-- someone or something might change the
589 permissions between the permissions check and the actual operation.
590 Just try the operation.)
592 Don't assume the UNIX user and group semantics: especially, don't
593 expect the C<< $< >> and C<< $> >> (or the C<$(> and C<$)>) to work
594 for switching identities (or memberships).
596 Don't assume set-uid and set-gid semantics. (And even if you do,
597 think twice: set-uid and set-gid are a known can of security worms.)
601 For those times when it is necessary to have platform-specific code,
602 consider keeping the platform-specific code in one place, making porting
603 to other platforms easier. Use the Config module and the special
604 variable C<$^O> to differentiate platforms, as described in
607 Be careful in the tests you supply with your module or programs.
608 Module code may be fully portable, but its tests might not be. This
609 often happens when tests spawn off other processes or call external
610 programs to aid in the testing, or when (as noted above) the tests
611 assume certain things about the filesystem and paths. Be careful
612 not to depend on a specific output style for errors, such as when
613 checking C<$!> after a system call. Some platforms expect a certain
614 output format, and perl on those platforms may have been adjusted
615 accordingly. Most specifically, don't anchor a regex when testing
620 Modules uploaded to CPAN are tested by a variety of volunteers on
621 different platforms. These CPAN testers are notified by mail of each
622 new upload, and reply to the list with PASS, FAIL, NA (not applicable to
623 this platform), or UNKNOWN (unknown), along with any relevant notations.
625 The purpose of the testing is twofold: one, to help developers fix any
626 problems in their code that crop up because of lack of testing on other
627 platforms; two, to provide users with information about whether
628 a given module works on a given platform.
632 =item Mailing list: cpan-testers@perl.org
634 =item Testing results: http://testers.cpan.org/
640 As of version 5.002, Perl is built with a C<$^O> variable that
641 indicates the operating system it was built on. This was implemented
642 to help speed up code that would otherwise have to C<use Config>
643 and use the value of C<$Config{osname}>. Of course, to get more
644 detailed information about the system, looking into C<%Config> is
645 certainly recommended.
647 C<%Config> cannot always be trusted, however, because it was built
648 at compile time. If perl was built in one place, then transferred
649 elsewhere, some values may be wrong. The values may even have been
650 edited after the fact.
654 Perl works on a bewildering variety of Unix and Unix-like platforms (see
655 e.g. most of the files in the F<hints/> directory in the source code kit).
656 On most of these systems, the value of C<$^O> (hence C<$Config{'osname'}>,
657 too) is determined either by lowercasing and stripping punctuation from the
658 first field of the string returned by typing C<uname -a> (or a similar command)
659 at the shell prompt or by testing the file system for the presence of
660 uniquely named files such as a kernel or header file. Here, for example,
661 are a few of the more popular Unix flavors:
663 uname $^O $Config{'archname'}
664 --------------------------------------------
666 BSD/OS bsdos i386-bsdos
667 dgux dgux AViiON-dgux
668 DYNIX/ptx dynixptx i386-dynixptx
669 FreeBSD freebsd freebsd-i386
670 Linux linux arm-linux
671 Linux linux i386-linux
672 Linux linux i586-linux
673 Linux linux ppc-linux
674 HP-UX hpux PA-RISC1.1
676 Mac OS X darwin darwin
677 MachTen PPC machten powerpc-machten
679 NeXT 4 next OPENSTEP-Mach
680 openbsd openbsd i386-openbsd
681 OSF1 dec_osf alpha-dec_osf
682 reliantunix-n svr4 RM400-svr4
683 SCO_SV sco_sv i386-sco_sv
684 SINIX-N svr4 RM400-svr4
685 sn4609 unicos CRAY_C90-unicos
686 sn6521 unicosmk t3e-unicosmk
687 sn9617 unicos CRAY_J90-unicos
688 SunOS solaris sun4-solaris
689 SunOS solaris i86pc-solaris
690 SunOS4 sunos sun4-sunos
692 Because the value of C<$Config{archname}> may depend on the
693 hardware architecture, it can vary more than the value of C<$^O>.
695 =head2 DOS and Derivatives
697 Perl has long been ported to Intel-style microcomputers running under
698 systems like PC-DOS, MS-DOS, OS/2, and most Windows platforms you can
699 bring yourself to mention (except for Windows CE, if you count that).
700 Users familiar with I<COMMAND.COM> or I<CMD.EXE> style shells should
701 be aware that each of these file specifications may have subtle
704 $filespec0 = "c:/foo/bar/file.txt";
705 $filespec1 = "c:\\foo\\bar\\file.txt";
706 $filespec2 = 'c:\foo\bar\file.txt';
707 $filespec3 = 'c:\\foo\\bar\\file.txt';
709 System calls accept either C</> or C<\> as the path separator.
710 However, many command-line utilities of DOS vintage treat C</> as
711 the option prefix, so may get confused by filenames containing C</>.
712 Aside from calling any external programs, C</> will work just fine,
713 and probably better, as it is more consistent with popular usage,
714 and avoids the problem of remembering what to backwhack and what
717 The DOS FAT filesystem can accommodate only "8.3" style filenames. Under
718 the "case-insensitive, but case-preserving" HPFS (OS/2) and NTFS (NT)
719 filesystems you may have to be careful about case returned with functions
720 like C<readdir> or used with functions like C<open> or C<opendir>.
722 DOS also treats several filenames as special, such as AUX, PRN,
723 NUL, CON, COM1, LPT1, LPT2, etc. Unfortunately, sometimes these
724 filenames won't even work if you include an explicit directory
725 prefix. It is best to avoid such filenames, if you want your code
726 to be portable to DOS and its derivatives. It's hard to know what
727 these all are, unfortunately.
729 Users of these operating systems may also wish to make use of
730 scripts such as I<pl2bat.bat> or I<pl2cmd> to
731 put wrappers around your scripts.
733 Newline (C<\n>) is translated as C<\015\012> by STDIO when reading from
734 and writing to files (see L<"Newlines">). C<binmode(FILEHANDLE)>
735 will keep C<\n> translated as C<\012> for that filehandle. Since it is a
736 no-op on other systems, C<binmode> should be used for cross-platform code
737 that deals with binary data. That's assuming you realize in advance
738 that your data is in binary. General-purpose programs should
739 often assume nothing about their data.
741 The C<$^O> variable and the C<$Config{archname}> values for various
742 DOSish perls are as follows:
744 OS $^O $Config{archname} ID Version
745 --------------------------------------------------------
749 Windows 3.1 ? ? 0 3 01
750 Windows 95 MSWin32 MSWin32-x86 1 4 00
751 Windows 98 MSWin32 MSWin32-x86 1 4 10
752 Windows ME MSWin32 MSWin32-x86 1 ?
753 Windows NT MSWin32 MSWin32-x86 2 4 xx
754 Windows NT MSWin32 MSWin32-ALPHA 2 4 xx
755 Windows NT MSWin32 MSWin32-ppc 2 4 xx
756 Windows 2000 MSWin32 MSWin32-x86 2 5 xx
757 Windows XP MSWin32 MSWin32-x86 2 ?
758 Windows CE MSWin32 ? 3
761 The various MSWin32 Perl's can distinguish the OS they are running on
762 via the value of the fifth element of the list returned from
763 Win32::GetOSVersion(). For example:
765 if ($^O eq 'MSWin32') {
766 my @os_version_info = Win32::GetOSVersion();
767 print +('3.1','95','NT')[$os_version_info[4]],"\n";
776 The djgpp environment for DOS, http://www.delorie.com/djgpp/
781 The EMX environment for DOS, OS/2, etc. emx@iaehv.nl,
782 http://www.leo.org/pub/comp/os/os2/leo/gnu/emx+gcc/index.html or
783 ftp://hobbes.nmsu.edu/pub/os2/dev/emx. Also L<perlos2>.
787 Build instructions for Win32 in L<perlwin32>, or under the Cygnus environment
792 The C<Win32::*> modules in L<Win32>.
796 The ActiveState Pages, http://www.activestate.com/
800 The Cygwin environment for Win32; F<README.cygwin> (installed
801 as L<perlcygwin>), http://www.cygwin.com/
805 The U/WIN environment for Win32,
806 http://www.research.att.com/sw/tools/uwin/
810 Build instructions for OS/2, L<perlos2>
816 Any module requiring XS compilation is right out for most people, because
817 MacPerl is built using non-free (and non-cheap!) compilers. Some XS
818 modules that can work with MacPerl are built and distributed in binary
821 Directories are specified as:
823 volume:folder:file for absolute pathnames
824 volume:folder: for absolute pathnames
825 :folder:file for relative pathnames
826 :folder: for relative pathnames
827 :file for relative pathnames
828 file for relative pathnames
830 Files are stored in the directory in alphabetical order. Filenames are
831 limited to 31 characters, and may include any character except for
832 null and C<:>, which is reserved as the path separator.
834 Instead of C<flock>, see C<FSpSetFLock> and C<FSpRstFLock> in the
835 Mac::Files module, or C<chmod(0444, ...)> and C<chmod(0666, ...)>.
837 In the MacPerl application, you can't run a program from the command line;
838 programs that expect C<@ARGV> to be populated can be edited with something
839 like the following, which brings up a dialog box asking for the command
843 @ARGV = split /\s+/, MacPerl::Ask('Arguments?');
846 A MacPerl script saved as a "droplet" will populate C<@ARGV> with the full
847 pathnames of the files dropped onto the script.
849 Mac users can run programs under a type of command line interface
850 under MPW (Macintosh Programmer's Workshop, a free development
851 environment from Apple). MacPerl was first introduced as an MPW
852 tool, and MPW can be used like a shell:
854 perl myscript.plx some arguments
856 ToolServer is another app from Apple that provides access to MPW tools
857 from MPW and the MacPerl app, which allows MacPerl programs to use
858 C<system>, backticks, and piped C<open>.
860 "S<Mac OS>" is the proper name for the operating system, but the value
861 in C<$^O> is "MacOS". To determine architecture, version, or whether
862 the application or MPW tool version is running, check:
864 $is_app = $MacPerl::Version =~ /App/;
865 $is_tool = $MacPerl::Version =~ /MPW/;
866 ($version) = $MacPerl::Version =~ /^(\S+)/;
867 $is_ppc = $MacPerl::Architecture eq 'MacPPC';
868 $is_68k = $MacPerl::Architecture eq 'Mac68K';
870 S<Mac OS X>, based on NeXT's OpenStep OS, runs MacPerl natively, under the
871 "Classic" environment. There is no "Carbon" version of MacPerl to run
872 under the primary Mac OS X environment. S<Mac OS X> and its Open Source
873 version, Darwin, both run Unix perl natively.
881 MacPerl Development, http://dev.macperl.org/ .
885 The MacPerl Pages, http://www.macperl.com/ .
889 The MacPerl mailing lists, http://lists.perl.org/ .
895 Perl on VMS is discussed in L<perlvms> in the perl distribution.
896 Perl on VMS can accept either VMS- or Unix-style file
897 specifications as in either of the following:
899 $ perl -ne "print if /perl_setup/i" SYS$LOGIN:LOGIN.COM
900 $ perl -ne "print if /perl_setup/i" /sys$login/login.com
902 but not a mixture of both as in:
904 $ perl -ne "print if /perl_setup/i" sys$login:/login.com
905 Can't open sys$login:/login.com: file specification syntax error
907 Interacting with Perl from the Digital Command Language (DCL) shell
908 often requires a different set of quotation marks than Unix shells do.
911 $ perl -e "print ""Hello, world.\n"""
914 There are several ways to wrap your perl scripts in DCL F<.COM> files, if
915 you are so inclined. For example:
917 $ write sys$output "Hello from DCL!"
919 $ then perl -x 'f$environment("PROCEDURE")
920 $ else perl -x - 'p1 'p2 'p3 'p4 'p5 'p6 'p7 'p8
921 $ deck/dollars="__END__"
924 print "Hello from Perl!\n";
929 Do take care with C<$ ASSIGN/nolog/user SYS$COMMAND: SYS$INPUT> if your
930 perl-in-DCL script expects to do things like C<< $read = <STDIN>; >>.
932 Filenames are in the format "name.extension;version". The maximum
933 length for filenames is 39 characters, and the maximum length for
934 extensions is also 39 characters. Version is a number from 1 to
935 32767. Valid characters are C</[A-Z0-9$_-]/>.
937 VMS's RMS filesystem is case-insensitive and does not preserve case.
938 C<readdir> returns lowercased filenames, but specifying a file for
939 opening remains case-insensitive. Files without extensions have a
940 trailing period on them, so doing a C<readdir> with a file named F<A.;5>
941 will return F<a.> (though that file could be opened with
944 RMS had an eight level limit on directory depths from any rooted logical
945 (allowing 16 levels overall) prior to VMS 7.2. Hence
946 C<PERL_ROOT:[LIB.2.3.4.5.6.7.8]> is a valid directory specification but
947 C<PERL_ROOT:[LIB.2.3.4.5.6.7.8.9]> is not. F<Makefile.PL> authors might
948 have to take this into account, but at least they can refer to the former
949 as C</PERL_ROOT/lib/2/3/4/5/6/7/8/>.
951 The VMS::Filespec module, which gets installed as part of the build
952 process on VMS, is a pure Perl module that can easily be installed on
953 non-VMS platforms and can be helpful for conversions to and from RMS
956 What C<\n> represents depends on the type of file opened. It usually
957 represents C<\012> but it could also be C<\015>, C<\012>, C<\015\012>,
958 C<\000>, C<\040>, or nothing depending on the file organiztion and
959 record format. The VMS::Stdio module provides access to the
960 special fopen() requirements of files with unusual attributes on VMS.
962 TCP/IP stacks are optional on VMS, so socket routines might not be
963 implemented. UDP sockets may not be supported.
965 The value of C<$^O> on OpenVMS is "VMS". To determine the architecture
966 that you are running on without resorting to loading all of C<%Config>
967 you can examine the content of the C<@INC> array like so:
969 if (grep(/VMS_AXP/, @INC)) {
970 print "I'm on Alpha!\n";
972 } elsif (grep(/VMS_VAX/, @INC)) {
973 print "I'm on VAX!\n";
976 print "I'm not so sure about where $^O is...\n";
979 On VMS, perl determines the UTC offset from the C<SYS$TIMEZONE_DIFFERENTIAL>
980 logical name. Although the VMS epoch began at 17-NOV-1858 00:00:00.00,
981 calls to C<localtime> are adjusted to count offsets from
982 01-JAN-1970 00:00:00.00, just like Unix.
990 F<README.vms> (installed as L<README_vms>), L<perlvms>
994 vmsperl list, majordomo@perl.org
996 (Put the words C<subscribe vmsperl> in message body.)
1000 vmsperl on the web, http://www.sidhe.org/vmsperl/index.html
1006 Perl on VOS is discussed in F<README.vos> in the perl distribution
1007 (installed as L<perlvos>). Perl on VOS can accept either VOS- or
1008 Unix-style file specifications as in either of the following:
1010 $ perl -ne "print if /perl_setup/i" >system>notices
1011 $ perl -ne "print if /perl_setup/i" /system/notices
1013 or even a mixture of both as in:
1015 $ perl -ne "print if /perl_setup/i" >system/notices
1017 Even though VOS allows the slash character to appear in object
1018 names, because the VOS port of Perl interprets it as a pathname
1019 delimiting character, VOS files, directories, or links whose names
1020 contain a slash character cannot be processed. Such files must be
1021 renamed before they can be processed by Perl. Note that VOS limits
1022 file names to 32 or fewer characters.
1024 See F<README.vos> for restrictions that apply when Perl is built
1025 with the alpha version of VOS POSIX.1 support.
1027 Perl on VOS is built without any extensions and does not support
1030 The value of C<$^O> on VOS is "VOS". To determine the architecture that
1031 you are running on without resorting to loading all of C<%Config> you
1032 can examine the content of the @INC array like so:
1035 print "I'm on a Stratus box!\n";
1037 print "I'm not on a Stratus box!\n";
1041 if (grep(/860/, @INC)) {
1042 print "This box is a Stratus XA/R!\n";
1044 } elsif (grep(/7100/, @INC)) {
1045 print "This box is a Stratus HP 7100 or 8xxx!\n";
1047 } elsif (grep(/8000/, @INC)) {
1048 print "This box is a Stratus HP 8xxx!\n";
1051 print "This box is a Stratus 68K!\n";
1064 The VOS mailing list.
1066 There is no specific mailing list for Perl on VOS. You can post
1067 comments to the comp.sys.stratus newsgroup, or subscribe to the general
1068 Stratus mailing list. Send a letter with "Subscribe Info-Stratus" in
1069 the message body to majordomo@list.stratagy.com.
1073 VOS Perl on the web at http://ftp.stratus.com/pub/vos/vos.html
1077 =head2 EBCDIC Platforms
1079 Recent versions of Perl have been ported to platforms such as OS/400 on
1080 AS/400 minicomputers as well as OS/390, VM/ESA, and BS2000 for S/390
1081 Mainframes. Such computers use EBCDIC character sets internally (usually
1082 Character Code Set ID 0037 for OS/400 and either 1047 or POSIX-BC for S/390
1083 systems). On the mainframe perl currently works under the "Unix system
1084 services for OS/390" (formerly known as OpenEdition), VM/ESA OpenEdition, or
1085 the BS200 POSIX-BC system (BS2000 is supported in perl 5.6 and greater).
1086 See L<perlos390> for details.
1088 As of R2.5 of USS for OS/390 and Version 2.3 of VM/ESA these Unix
1089 sub-systems do not support the C<#!> shebang trick for script invocation.
1090 Hence, on OS/390 and VM/ESA perl scripts can be executed with a header
1091 similar to the following simple script:
1094 eval 'exec /usr/local/bin/perl -S $0 ${1+"$@"}'
1096 #!/usr/local/bin/perl # just a comment really
1098 print "Hello from perl!\n";
1100 OS/390 will support the C<#!> shebang trick in release 2.8 and beyond.
1101 Calls to C<system> and backticks can use POSIX shell syntax on all
1104 On the AS/400, if PERL5 is in your library list, you may need
1105 to wrap your perl scripts in a CL procedure to invoke them like so:
1108 CALL PGM(PERL5/PERL) PARM('/QOpenSys/hello.pl')
1111 This will invoke the perl script F<hello.pl> in the root of the
1112 QOpenSys file system. On the AS/400 calls to C<system> or backticks
1115 On these platforms, bear in mind that the EBCDIC character set may have
1116 an effect on what happens with some perl functions (such as C<chr>,
1117 C<pack>, C<print>, C<printf>, C<ord>, C<sort>, C<sprintf>, C<unpack>), as
1118 well as bit-fiddling with ASCII constants using operators like C<^>, C<&>
1119 and C<|>, not to mention dealing with socket interfaces to ASCII computers
1120 (see L<"Newlines">).
1122 Fortunately, most web servers for the mainframe will correctly
1123 translate the C<\n> in the following statement to its ASCII equivalent
1124 (C<\r> is the same under both Unix and OS/390 & VM/ESA):
1126 print "Content-type: text/html\r\n\r\n";
1128 The values of C<$^O> on some of these platforms includes:
1130 uname $^O $Config{'archname'}
1131 --------------------------------------------
1134 POSIX-BC posix-bc BS2000-posix-bc
1137 Some simple tricks for determining if you are running on an EBCDIC
1138 platform could include any of the following (perhaps all):
1140 if ("\t" eq "\05") { print "EBCDIC may be spoken here!\n"; }
1142 if (ord('A') == 193) { print "EBCDIC may be spoken here!\n"; }
1144 if (chr(169) eq 'z') { print "EBCDIC may be spoken here!\n"; }
1146 One thing you may not want to rely on is the EBCDIC encoding
1147 of punctuation characters since these may differ from code page to code
1148 page (and once your module or script is rumoured to work with EBCDIC,
1149 folks will want it to work with all EBCDIC character sets).
1159 L<perlos390>, F<README.os390>, F<perlbs2000>, F<README.vmesa>,
1164 The perl-mvs@perl.org list is for discussion of porting issues as well as
1165 general usage issues for all EBCDIC Perls. Send a message body of
1166 "subscribe perl-mvs" to majordomo@perl.org.
1170 AS/400 Perl information at
1171 http://as400.rochester.ibm.com/
1172 as well as on CPAN in the F<ports/> directory.
1176 =head2 Acorn RISC OS
1178 Because Acorns use ASCII with newlines (C<\n>) in text files as C<\012> like
1179 Unix, and because Unix filename emulation is turned on by default,
1180 most simple scripts will probably work "out of the box". The native
1181 filesystem is modular, and individual filesystems are free to be
1182 case-sensitive or insensitive, and are usually case-preserving. Some
1183 native filesystems have name length limits, which file and directory
1184 names are silently truncated to fit. Scripts should be aware that the
1185 standard filesystem currently has a name length limit of B<10>
1186 characters, with up to 77 items in a directory, but other filesystems
1187 may not impose such limitations.
1189 Native filenames are of the form
1191 Filesystem#Special_Field::DiskName.$.Directory.Directory.File
1195 Special_Field is not usually present, but may contain . and $ .
1196 Filesystem =~ m|[A-Za-z0-9_]|
1197 DsicName =~ m|[A-Za-z0-9_/]|
1198 $ represents the root directory
1199 . is the path separator
1200 @ is the current directory (per filesystem but machine global)
1201 ^ is the parent directory
1202 Directory and File =~ m|[^\0- "\.\$\%\&:\@\\^\|\177]+|
1204 The default filename translation is roughly C<tr|/.|./|;>
1206 Note that C<"ADFS::HardDisk.$.File" ne 'ADFS::HardDisk.$.File'> and that
1207 the second stage of C<$> interpolation in regular expressions will fall
1208 foul of the C<$.> if scripts are not careful.
1210 Logical paths specified by system variables containing comma-separated
1211 search lists are also allowed; hence C<System:Modules> is a valid
1212 filename, and the filesystem will prefix C<Modules> with each section of
1213 C<System$Path> until a name is made that points to an object on disk.
1214 Writing to a new file C<System:Modules> would be allowed only if
1215 C<System$Path> contains a single item list. The filesystem will also
1216 expand system variables in filenames if enclosed in angle brackets, so
1217 C<< <System$Dir>.Modules >> would look for the file
1218 S<C<$ENV{'System$Dir'} . 'Modules'>>. The obvious implication of this is
1219 that B<fully qualified filenames can start with C<< <> >>> and should
1220 be protected when C<open> is used for input.
1222 Because C<.> was in use as a directory separator and filenames could not
1223 be assumed to be unique after 10 characters, Acorn implemented the C
1224 compiler to strip the trailing C<.c> C<.h> C<.s> and C<.o> suffix from
1225 filenames specified in source code and store the respective files in
1226 subdirectories named after the suffix. Hence files are translated:
1229 C:foo.h C:h.foo (logical path variable)
1230 sys/os.h sys.h.os (C compiler groks Unix-speak)
1231 10charname.c c.10charname
1232 10charname.o o.10charname
1233 11charname_.c c.11charname (assuming filesystem truncates at 10)
1235 The Unix emulation library's translation of filenames to native assumes
1236 that this sort of translation is required, and it allows a user-defined list
1237 of known suffixes that it will transpose in this fashion. This may
1238 seem transparent, but consider that with these rules C<foo/bar/baz.h>
1239 and C<foo/bar/h/baz> both map to C<foo.bar.h.baz>, and that C<readdir> and
1240 C<glob> cannot and do not attempt to emulate the reverse mapping. Other
1241 C<.>'s in filenames are translated to C</>.
1243 As implied above, the environment accessed through C<%ENV> is global, and
1244 the convention is that program specific environment variables are of the
1245 form C<Program$Name>. Each filesystem maintains a current directory,
1246 and the current filesystem's current directory is the B<global> current
1247 directory. Consequently, sociable programs don't change the current
1248 directory but rely on full pathnames, and programs (and Makefiles) cannot
1249 assume that they can spawn a child process which can change the current
1250 directory without affecting its parent (and everyone else for that
1253 Because native operating system filehandles are global and are currently
1254 allocated down from 255, with 0 being a reserved value, the Unix emulation
1255 library emulates Unix filehandles. Consequently, you can't rely on
1256 passing C<STDIN>, C<STDOUT>, or C<STDERR> to your children.
1258 The desire of users to express filenames of the form
1259 C<< <Foo$Dir>.Bar >> on the command line unquoted causes problems,
1260 too: C<``> command output capture has to perform a guessing game. It
1261 assumes that a string C<< <[^<>]+\$[^<>]> >> is a
1262 reference to an environment variable, whereas anything else involving
1263 C<< < >> or C<< > >> is redirection, and generally manages to be 99%
1264 right. Of course, the problem remains that scripts cannot rely on any
1265 Unix tools being available, or that any tools found have Unix-like command
1268 Extensions and XS are, in theory, buildable by anyone using free
1269 tools. In practice, many don't, as users of the Acorn platform are
1270 used to binary distributions. MakeMaker does run, but no available
1271 make currently copes with MakeMaker's makefiles; even if and when
1272 this should be fixed, the lack of a Unix-like shell will cause
1273 problems with makefile rules, especially lines of the form C<cd
1274 sdbm && make all>, and anything using quoting.
1276 "S<RISC OS>" is the proper name for the operating system, but the value
1277 in C<$^O> is "riscos" (because we don't like shouting).
1281 Perl has been ported to many platforms that do not fit into any of
1282 the categories listed above. Some, such as AmigaOS, Atari MiNT,
1283 BeOS, HP MPE/iX, QNX, Plan 9, and VOS, have been well-integrated
1284 into the standard Perl source code kit. You may need to see the
1285 F<ports/> directory on CPAN for information, and possibly binaries,
1286 for the likes of: aos, Atari ST, lynxos, riscos, Novell Netware,
1287 Tandem Guardian, I<etc.> (Yes, we know that some of these OSes may
1288 fall under the Unix category, but we are not a standards body.)
1290 Some approximate operating system names and their C<$^O> values
1291 in the "OTHER" category include:
1293 OS $^O $Config{'archname'}
1294 ------------------------------------------
1295 Amiga DOS amigaos m68k-amigos
1296 MPE/iX mpeix PA-RISC1.1
1304 Amiga, F<README.amiga> (installed as L<perlamiga>).
1308 Atari, F<README.mint> and Guido Flohr's web page
1309 http://stud.uni-sb.de/~gufl0000/
1313 Be OS, F<README.beos>
1317 HP 300 MPE/iX, F<README.mpeix> and Mark Bixby's web page
1318 http://www.bixby.org/mark/perlix.html
1322 A free perl5-based PERL.NLM for Novell Netware is available in
1323 precompiled binary and source code form from http://www.novell.com/
1324 as well as from CPAN.
1328 Plan 9, F<README.plan9>
1332 =head1 FUNCTION IMPLEMENTATIONS
1334 Listed below are functions that are either completely unimplemented
1335 or else have been implemented differently on various platforms.
1336 Following each description will be, in parentheses, a list of
1337 platforms that the description applies to.
1339 The list may well be incomplete, or even wrong in some places. When
1340 in doubt, consult the platform-specific README files in the Perl
1341 source distribution, and any other documentation resources accompanying
1344 Be aware, moreover, that even among Unix-ish systems there are variations.
1346 For many functions, you can also query C<%Config>, exported by
1347 default from the Config module. For example, to check whether the
1348 platform has the C<lstat> call, check C<$Config{d_lstat}>. See
1349 L<Config> for a full description of available variables.
1351 =head2 Alphabetical Listing of Perl Functions
1361 C<-r>, C<-w>, and C<-x> have a limited meaning only; directories
1362 and applications are executable, and there are no uid/gid
1363 considerations. C<-o> is not supported. (S<Mac OS>)
1365 C<-r>, C<-w>, C<-x>, and C<-o> tell whether the file is accessible,
1366 which may not reflect UIC-based file protections. (VMS)
1368 C<-s> returns the size of the data fork, not the total size of data fork
1369 plus resource fork. (S<Mac OS>).
1371 C<-s> by name on an open file will return the space reserved on disk,
1372 rather than the current extent. C<-s> on an open filehandle returns the
1373 current size. (S<RISC OS>)
1375 C<-R>, C<-W>, C<-X>, C<-O> are indistinguishable from C<-r>, C<-w>,
1376 C<-x>, C<-o>. (S<Mac OS>, Win32, VMS, S<RISC OS>)
1378 C<-b>, C<-c>, C<-k>, C<-g>, C<-p>, C<-u>, C<-A> are not implemented.
1381 C<-g>, C<-k>, C<-l>, C<-p>, C<-u>, C<-A> are not particularly meaningful.
1382 (Win32, VMS, S<RISC OS>)
1384 C<-d> is true if passed a device spec without an explicit directory.
1387 C<-T> and C<-B> are implemented, but might misclassify Mac text files
1388 with foreign characters; this is the case will all platforms, but may
1389 affect S<Mac OS> often. (S<Mac OS>)
1391 C<-x> (or C<-X>) determine if a file ends in one of the executable
1392 suffixes. C<-S> is meaningless. (Win32)
1394 C<-x> (or C<-X>) determine if a file has an executable file type.
1401 Not implemented. (Win32)
1403 =item binmode FILEHANDLE
1405 Meaningless. (S<Mac OS>, S<RISC OS>)
1407 Reopens file and restores pointer; if function fails, underlying
1408 filehandle may be closed, or pointer may be in a different position.
1411 The value returned by C<tell> may be affected after the call, and
1412 the filehandle may be flushed. (Win32)
1416 Only limited meaning. Disabling/enabling write permission is mapped to
1417 locking/unlocking the file. (S<Mac OS>)
1419 Only good for changing "owner" read-write access, "group", and "other"
1420 bits are meaningless. (Win32)
1422 Only good for changing "owner" and "other" read-write access. (S<RISC OS>)
1424 Access permissions are mapped onto VOS access-control list changes. (VOS)
1428 Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>, VOS)
1430 Does nothing, but won't fail. (Win32)
1432 =item chroot FILENAME
1436 Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>, VOS, VM/ESA)
1438 =item crypt PLAINTEXT,SALT
1440 May not be available if library or source was not provided when building
1443 Not implemented. (VOS)
1447 Not implemented. (VMS, Plan9, VOS)
1449 =item dbmopen HASH,DBNAME,MODE
1451 Not implemented. (VMS, Plan9, VOS)
1455 Not useful. (S<Mac OS>, S<RISC OS>)
1457 Not implemented. (Win32)
1459 Invokes VMS debugger. (VMS)
1463 Not implemented. (S<Mac OS>)
1465 Implemented via Spawn. (VM/ESA)
1467 Does not automatically flush output handles on some platforms.
1468 (SunOS, Solaris, HP-UX)
1474 Emulates UNIX exit() (which considers C<exit 1> to indicate an error) by
1475 mapping the C<1> to SS$_ABORT (C<44>). This behavior may be overridden
1476 with the pragma C<use vmsish 'exit'>. As with the CRTL's exit()
1477 function, C<exit 0> is also mapped to an exit status of SS$_NORMAL
1478 (C<1>); this mapping cannot be overridden. Any other argument to exit()
1479 is used directly as Perl's exit status. (VMS)
1481 =item fcntl FILEHANDLE,FUNCTION,SCALAR
1483 Not implemented. (Win32, VMS)
1485 =item flock FILEHANDLE,OPERATION
1487 Not implemented (S<Mac OS>, VMS, S<RISC OS>, VOS).
1489 Available only on Windows NT (not on Windows 95). (Win32)
1493 Not implemented. (S<Mac OS>, AmigaOS, S<RISC OS>, VOS, VM/ESA)
1495 Emulated using multiple interpreters. See L<perlfork>. (Win32)
1497 Does not automatically flush output handles on some platforms.
1498 (SunOS, Solaris, HP-UX)
1502 Not implemented. (S<Mac OS>, S<RISC OS>)
1506 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
1510 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
1512 =item getpriority WHICH,WHO
1514 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
1518 Not implemented. (S<Mac OS>, Win32)
1520 Not useful. (S<RISC OS>)
1524 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
1526 =item getnetbyname NAME
1528 Not implemented. (S<Mac OS>, Win32, Plan9)
1532 Not implemented. (S<Mac OS>, Win32)
1534 Not useful. (S<RISC OS>)
1538 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
1540 =item getnetbyaddr ADDR,ADDRTYPE
1542 Not implemented. (S<Mac OS>, Win32, Plan9)
1544 =item getprotobynumber NUMBER
1546 Not implemented. (S<Mac OS>)
1548 =item getservbyport PORT,PROTO
1550 Not implemented. (S<Mac OS>)
1554 Not implemented. (S<Mac OS>, Win32, VM/ESA)
1558 Not implemented. (S<Mac OS>, Win32, VMS, VM/ESA)
1562 Not implemented. (S<Mac OS>, Win32)
1566 Not implemented. (S<Mac OS>, Win32, Plan9)
1570 Not implemented. (S<Mac OS>, Win32, Plan9)
1574 Not implemented. (Win32, Plan9)
1578 Not implemented. (S<Mac OS>, Win32, S<RISC OS>)
1582 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
1584 =item sethostent STAYOPEN
1586 Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>)
1588 =item setnetent STAYOPEN
1590 Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>)
1592 =item setprotoent STAYOPEN
1594 Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>)
1596 =item setservent STAYOPEN
1598 Not implemented. (Plan9, Win32, S<RISC OS>)
1602 Not implemented. (S<Mac OS>, MPE/iX, VM/ESA, Win32)
1606 Not implemented. (S<Mac OS>, MPE/iX, S<RISC OS>, VM/ESA, VMS, Win32)
1610 Not implemented. (S<Mac OS>, Win32)
1614 Not implemented. (S<Mac OS>, Win32, Plan9)
1618 Not implemented. (S<Mac OS>, Win32, Plan9)
1622 Not implemented. (Plan9, Win32)
1624 =item getsockopt SOCKET,LEVEL,OPTNAME
1626 Not implemented. (Plan9)
1632 This operator is implemented via the File::Glob extension on most
1633 platforms. See L<File::Glob> for portability information.
1635 =item ioctl FILEHANDLE,FUNCTION,SCALAR
1637 Not implemented. (VMS)
1639 Available only for socket handles, and it does what the ioctlsocket() call
1640 in the Winsock API does. (Win32)
1642 Available only for socket handles. (S<RISC OS>)
1644 =item kill SIGNAL, LIST
1646 C<kill(0, LIST)> is implemented for the sake of taint checking;
1647 use with other signals is unimplemented. (S<Mac OS>)
1649 Not implemented, hence not useful for taint checking. (S<RISC OS>)
1651 C<kill()> doesn't have the semantics of C<raise()>, i.e. it doesn't send
1652 a signal to the identified process like it does on Unix platforms.
1653 Instead C<kill($sig, $pid)> terminates the process identified by $pid,
1654 and makes it exit immediately with exit status $sig. As in Unix, if
1655 $sig is 0 and the specified process exists, it returns true without
1656 actually terminating it. (Win32)
1658 =item link OLDFILE,NEWFILE
1660 Not implemented. (S<Mac OS>, MPE/iX, VMS, S<RISC OS>)
1662 Link count not updated because hard links are not quite that hard
1663 (They are sort of half-way between hard and soft links). (AmigaOS)
1665 Hard links are implemented on Win32 (Windows NT and Windows 2000)
1668 =item lstat FILEHANDLE
1674 Not implemented. (VMS, S<RISC OS>)
1676 Return values (especially for device and inode) may be bogus. (Win32)
1678 =item msgctl ID,CMD,ARG
1680 =item msgget KEY,FLAGS
1682 =item msgsnd ID,MSG,FLAGS
1684 =item msgrcv ID,VAR,SIZE,TYPE,FLAGS
1686 Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>, VOS)
1688 =item open FILEHANDLE,EXPR
1690 =item open FILEHANDLE
1692 The C<|> variants are supported only if ToolServer is installed.
1695 open to C<|-> and C<-|> are unsupported. (S<Mac OS>, Win32, S<RISC OS>)
1697 Opening a process does not automatically flush output handles on some
1698 platforms. (SunOS, Solaris, HP-UX)
1700 =item pipe READHANDLE,WRITEHANDLE
1702 Very limited functionality. (MiNT)
1708 Not implemented. (Win32, VMS, S<RISC OS>)
1710 =item select RBITS,WBITS,EBITS,TIMEOUT
1712 Only implemented on sockets. (Win32, VMS)
1714 Only reliable on sockets. (S<RISC OS>)
1716 Note that the C<select FILEHANDLE> form is generally portable.
1718 =item semctl ID,SEMNUM,CMD,ARG
1720 =item semget KEY,NSEMS,FLAGS
1722 =item semop KEY,OPSTRING
1724 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
1728 Not implemented. (MPE/iX, Win32)
1730 =item setpgrp PID,PGRP
1732 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
1734 =item setpriority WHICH,WHO,PRIORITY
1736 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
1740 Not implemented. (MPE/iX, Win32)
1742 =item setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL
1744 Not implemented. (Plan9)
1746 =item shmctl ID,CMD,ARG
1748 =item shmget KEY,SIZE,FLAGS
1750 =item shmread ID,VAR,POS,SIZE
1752 =item shmwrite ID,STRING,POS,SIZE
1754 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
1756 =item sockatmark SOCKET
1758 A relatively recent addition to socket functions, may not
1759 be implemented even in UNIX platforms.
1761 =item socketpair SOCKET1,SOCKET2,DOMAIN,TYPE,PROTOCOL
1763 Not implemented. (Win32, VMS, S<RISC OS>, VOS, VM/ESA)
1765 =item stat FILEHANDLE
1771 Platforms that do not have rdev, blksize, or blocks will return these
1772 as '', so numeric comparison or manipulation of these fields may cause
1773 'not numeric' warnings.
1775 mtime and atime are the same thing, and ctime is creation time instead of
1776 inode change time. (S<Mac OS>)
1778 device and inode are not meaningful. (Win32)
1780 device and inode are not necessarily reliable. (VMS)
1782 mtime, atime and ctime all return the last modification time. Device and
1783 inode are not necessarily reliable. (S<RISC OS>)
1785 dev, rdev, blksize, and blocks are not available. inode is not
1786 meaningful and will differ between stat calls on the same file. (os2)
1788 some versions of cygwin when doing a stat("foo") and if not finding it
1789 may then attempt to stat("foo.exe") (Cygwin)
1791 =item symlink OLDFILE,NEWFILE
1793 Not implemented. (Win32, VMS, S<RISC OS>)
1797 Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
1799 =item sysopen FILEHANDLE,FILENAME,MODE,PERMS
1801 The traditional "0", "1", and "2" MODEs are implemented with different
1802 numeric values on some systems. The flags exported by C<Fcntl>
1803 (O_RDONLY, O_WRONLY, O_RDWR) should work everywhere though. (S<Mac
1804 OS>, OS/390, VM/ESA)
1808 In general, do not assume the UNIX/POSIX semantics that you can shift
1809 C<$?> right by eight to get the exit value, or that C<$? & 127>
1810 would give you the number of the signal that terminated the program,
1811 or that C<$? & 128> would test true if the program was terminated by a
1812 coredump. Instead, use the POSIX W*() interfaces: for example, use
1813 WIFEXITED($?) an WEXITVALUE($?) to test for a normal exit and the exit
1814 value, and WIFSIGNALED($?) and WTERMSIG($?) for a signal exit and the
1815 signal. Core dumping is not a portable concept, so there's no portable
1816 way to test for that.
1818 Only implemented if ToolServer is installed. (S<Mac OS>)
1820 As an optimization, may not call the command shell specified in
1821 C<$ENV{PERL5SHELL}>. C<system(1, @args)> spawns an external
1822 process and immediately returns its process designator, without
1823 waiting for it to terminate. Return value may be used subsequently
1824 in C<wait> or C<waitpid>. Failure to spawn() a subprocess is indicated
1825 by setting $? to "255 << 8". C<$?> is set in a way compatible with
1826 Unix (i.e. the exitstatus of the subprocess is obtained by "$? >> 8",
1827 as described in the documentation). (Win32)
1829 There is no shell to process metacharacters, and the native standard is
1830 to pass a command line terminated by "\n" "\r" or "\0" to the spawned
1831 program. Redirection such as C<< > foo >> is performed (if at all) by
1832 the run time library of the spawned program. C<system> I<list> will call
1833 the Unix emulation library's C<exec> emulation, which attempts to provide
1834 emulation of the stdin, stdout, stderr in force in the parent, providing
1835 the child program uses a compatible version of the emulation library.
1836 I<scalar> will call the native command line direct and no such emulation
1837 of a child Unix program will exists. Mileage B<will> vary. (S<RISC OS>)
1839 Far from being POSIX compliant. Because there may be no underlying
1840 /bin/sh tries to work around the problem by forking and execing the
1841 first token in its argument string. Handles basic redirection
1842 ("<" or ">") on its own behalf. (MiNT)
1844 Does not automatically flush output handles on some platforms.
1845 (SunOS, Solaris, HP-UX)
1847 The return value is POSIX-like (shifted up by 8 bits), which only allows
1848 room for a made-up value derived from the severity bits of the native
1849 32-bit condition code (unless overridden by C<use vmsish 'status'>).
1850 For more details see L<perlvms/$?>. (VMS)
1854 Only the first entry returned is nonzero. (S<Mac OS>)
1856 "cumulative" times will be bogus. On anything other than Windows NT
1857 or Windows 2000, "system" time will be bogus, and "user" time is
1858 actually the time returned by the clock() function in the C runtime
1861 Not useful. (S<RISC OS>)
1863 =item truncate FILEHANDLE,LENGTH
1865 =item truncate EXPR,LENGTH
1867 Not implemented. (Older versions of VMS)
1869 Truncation to zero-length only. (VOS)
1871 If a FILEHANDLE is supplied, it must be writable and opened in append
1872 mode (i.e., use C<<< open(FH, '>>filename') >>>
1873 or C<sysopen(FH,...,O_APPEND|O_RDWR)>. If a filename is supplied, it
1874 should not be held open elsewhere. (Win32)
1880 Returns undef where unavailable, as of version 5.005.
1882 C<umask> works but the correct permissions are set only when the file
1883 is finally closed. (AmigaOS)
1887 Only the modification time is updated. (S<BeOS>, S<Mac OS>, VMS, S<RISC OS>)
1889 May not behave as expected. Behavior depends on the C runtime
1890 library's implementation of utime(), and the filesystem being
1891 used. The FAT filesystem typically does not support an "access
1892 time" field, and it may limit timestamps to a granularity of
1893 two seconds. (Win32)
1897 =item waitpid PID,FLAGS
1899 Not implemented. (S<Mac OS>, VOS)
1901 Can only be applied to process handles returned for processes spawned
1902 using C<system(1, ...)> or pseudo processes created with C<fork()>. (Win32)
1904 Not useful. (S<RISC OS>)
1912 =item v1.48, 02 February 2001
1914 Various updates from perl5-porters over the past year, supported
1915 platforms update from Jarkko Hietaniemi.
1917 =item v1.47, 22 March 2000
1919 Various cleanups from Tom Christiansen, including migration of
1920 long platform listings from L<perl>.
1922 =item v1.46, 12 February 2000
1924 Updates for VOS and MPE/iX. (Peter Prymmer) Other small changes.
1926 =item v1.45, 20 December 1999
1928 Small changes from 5.005_63 distribution, more changes to EBCDIC info.
1930 =item v1.44, 19 July 1999
1932 A bunch of updates from Peter Prymmer for C<$^O> values,
1933 endianness, File::Spec, VMS, BS2000, OS/400.
1935 =item v1.43, 24 May 1999
1937 Added a lot of cleaning up from Tom Christiansen.
1939 =item v1.42, 22 May 1999
1941 Added notes about tests, sprintf/printf, and epoch offsets.
1943 =item v1.41, 19 May 1999
1945 Lots more little changes to formatting and content.
1947 Added a bunch of C<$^O> and related values
1948 for various platforms; fixed mail and web addresses, and added
1949 and changed miscellaneous notes. (Peter Prymmer)
1951 =item v1.40, 11 April 1999
1953 Miscellaneous changes.
1955 =item v1.39, 11 February 1999
1957 Changes from Jarkko and EMX URL fixes Michael Schwern. Additional
1958 note about newlines added.
1960 =item v1.38, 31 December 1998
1962 More changes from Jarkko.
1964 =item v1.37, 19 December 1998
1966 More minor changes. Merge two separate version 1.35 documents.
1968 =item v1.36, 9 September 1998
1970 Updated for Stratus VOS. Also known as version 1.35.
1972 =item v1.35, 13 August 1998
1974 Integrate more minor changes, plus addition of new sections under
1975 L<"ISSUES">: L<"Numbers endianness and Width">,
1976 L<"Character sets and character encoding">,
1977 L<"Internationalisation">.
1979 =item v1.33, 06 August 1998
1981 Integrate more minor changes.
1983 =item v1.32, 05 August 1998
1985 Integrate more minor changes.
1987 =item v1.30, 03 August 1998
1989 Major update for RISC OS, other minor changes.
1991 =item v1.23, 10 July 1998
1993 First public release with perl5.005.
1997 =head1 Supported Platforms
1999 As of early 2001 (the Perl releases 5.6.1 and 5.7.1), the following
2000 platforms are able to build Perl from the standard source code
2001 distribution available at http://www.cpan.org/src/index.html
2024 Tru64 UNIX (DEC OSF/1, Digital UNIX)
2030 1) in DOS mode either the DOS or OS/2 ports can be used
2031 2) Mac OS Classic (pre-X) is almost 5.6.1-ready; building from
2032 the source does work with 5.6.1, but additional MacOS specific
2033 source code is needed for a complete build. See the web
2034 site http://dev.macperl.org/ for more information.
2035 3) compilers: Borland, Cygwin, Mingw32 EGCS/GCC, VC++
2037 The following platforms worked for the previous releases (5.6.0 and 5.7.0),
2038 but we did not manage to test these in time for the 5.7.1 release.
2039 There is a very good chance that these will work fine with the 5.7.1.
2057 The following platform worked for the 5.005_03 major release but not
2058 for 5.6.0. Standardization on UTF-8 as the internal string
2059 representation in 5.6.0 and 5.6.1 introduced incompatibilities in this
2060 EBCDIC platform. While Perl 5.7.1 will build on this platform some
2061 regression tests may fail and the C<use utf8;> pragma typically
2062 introduces text handling errors.
2066 1) previously known as MVS, about to become z/OS.
2068 Strongly related to the OS/390 platform by also being EBCDIC-based
2069 mainframe platforms are the following platforms:
2074 These are also expected to work, albeit with no UTF-8 support, under 5.6.1
2075 for the same reasons as OS/390. Contact the mailing list perl-mvs@perl.org
2078 The following platforms have been known to build Perl from source in
2079 the past (5.005_03 and earlier), but we haven't been able to verify
2080 their status for the current release, either because the
2081 hardware/software platforms are rare or because we don't have an
2082 active champion on these platforms--or both. They used to work,
2083 though, so go ahead and try compiling them, and let perlbug@perl.org
2122 Support for the following platform is planned for a future Perl release:
2126 The following platforms have their own source code distributions and
2127 binaries available via http://www.cpan.org/ports/index.html:
2133 Tandem Guardian 5.004
2135 The following platforms have only binaries available via
2136 http://www.cpan.org/ports/index.html :
2140 Acorn RISCOS 5.005_02
2144 Although we do suggest that you always build your own Perl from
2145 the source code, both for maximal configurability and for security,
2146 in case you are in a hurry you can check
2147 http://www.cpan.org/ports/index.html for binary distributions.
2151 L<perlaix>, L<perlapollo>, L<perlamiga>, L<perlbeos>, L<perlbs200>,
2152 L<perlce>, L<perlcygwin>, L<perldgux>, L<perldos>, L<perlepoc>, L<perlebcdic>,
2153 L<perlhurd>, L<perlhpux>, L<perlmachten>, L<perlmacos>, L<perlmint>,
2154 L<perlmpeix>, L<perlnetware>, L<perlos2>, L<perlos390>, L<perlplan9>,
2155 L<perlqnx>, L<perlsolaris>, L<perltru64>, L<perlunicode>,
2156 L<perlvmesa>, L<perlvms>, L<perlvos>, L<perlwin32>, and L<Win32>.
2158 =head1 AUTHORS / CONTRIBUTORS
2160 Abigail <abigail@foad.org>,
2161 Charles Bailey <bailey@newman.upenn.edu>,
2162 Graham Barr <gbarr@pobox.com>,
2163 Tom Christiansen <tchrist@perl.com>,
2164 Nicholas Clark <nick@ccl4.org>,
2165 Thomas Dorner <Thomas.Dorner@start.de>,
2166 Andy Dougherty <doughera@lafayette.edu>,
2167 Dominic Dunlop <domo@computer.org>,
2168 Neale Ferguson <neale@vma.tabnsw.com.au>,
2169 David J. Fiander <davidf@mks.com>,
2170 Paul Green <Paul_Green@stratus.com>,
2171 M.J.T. Guy <mjtg@cam.ac.uk>,
2172 Jarkko Hietaniemi <jhi@iki.fi>,
2173 Luther Huffman <lutherh@stratcom.com>,
2174 Nick Ing-Simmons <nick@ing-simmons.net>,
2175 Andreas J. KE<ouml>nig <a.koenig@mind.de>,
2176 Markus Laker <mlaker@contax.co.uk>,
2177 Andrew M. Langmead <aml@world.std.com>,
2178 Larry Moore <ljmoore@freespace.net>,
2179 Paul Moore <Paul.Moore@uk.origin-it.com>,
2180 Chris Nandor <pudge@pobox.com>,
2181 Matthias Neeracher <neeri@iis.ee.ethz.ch>,
2182 Philip Newton <pne@cpan.org>,
2183 Gary Ng <71564.1743@CompuServe.COM>,
2184 Tom Phoenix <rootbeer@teleport.com>,
2185 AndrE<eacute> Pirard <A.Pirard@ulg.ac.be>,
2186 Peter Prymmer <pvhp@forte.com>,
2187 Hugo van der Sanden <hv@crypt0.demon.co.uk>,
2188 Gurusamy Sarathy <gsar@activestate.com>,
2189 Paul J. Schinder <schinder@pobox.com>,
2190 Michael G Schwern <schwern@pobox.com>,
2191 Dan Sugalski <dan@sidhe.org>,
2192 Nathan Torkington <gnat@frii.com>.
2196 Version 1.50, last modified 10 Jul 2001