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1=head1 NAME
2
3perlport - Writing portable Perl
4
5
6=head1 DESCRIPTION
7
8Perl runs on a variety of operating systems. While most of them share
9a lot in common, they also have their own very particular and unique
10features.
11
12This document is meant to help you to find out what constitutes portable
0a47030a 13Perl code, so that once you have made your decision to write portably,
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14you know where the lines are drawn, and you can stay within them.
15
16There is a tradeoff between taking full advantage of B<a> particular type
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17of computer, and taking advantage of a full B<range> of them. Naturally,
18as you make your range bigger (and thus more diverse), the common
19denominators drop, and you are left with fewer areas of common ground in
20which you can operate to accomplish a particular task. Thus, when you
21begin attacking a problem, it is important to consider which part of the
22tradeoff curve you want to operate under. Specifically, whether it is
23important to you that the task that you are coding needs the full
24generality of being portable, or if it is sufficient to just get the job
25done. This is the hardest choice to be made. The rest is easy, because
26Perl provides lots of choices, whichever way you want to approach your
27problem.
28
29Looking at it another way, writing portable code is usually about
30willfully limiting your available choices. Naturally, it takes discipline
31to do that.
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32
33Be aware of two important points:
34
35=over 4
36
37=item Not all Perl programs have to be portable
38
39There is no reason why you should not use Perl as a language to glue Unix
40tools together, or to prototype a Macintosh application, or to manage the
41Windows registry. If it makes no sense to aim for portability for one
42reason or another in a given program, then don't bother.
43
44=item The vast majority of Perl B<is> portable
45
46Don't be fooled into thinking that it is hard to create portable Perl
47code. It isn't. Perl tries its level-best to bridge the gaps between
48what's available on different platforms, and all the means available to
49use those features. Thus almost all Perl code runs on any machine
50without modification. But there I<are> some significant issues in
51writing portable code, and this document is entirely about those issues.
52
53=back
54
55Here's the general rule: When you approach a task that is commonly done
56using a whole range of platforms, think in terms of writing portable
57code. That way, you don't sacrifice much by way of the implementation
58choices you can avail yourself of, and at the same time you can give
59your users lots of platform choices. On the other hand, when you have to
60take advantage of some unique feature of a particular platform, as is
61often the case with systems programming (whether for Unix, Windows,
62S<Mac OS>, VMS, etc.), consider writing platform-specific code.
63
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64When the code will run on only two or three operating systems, then you
65may only need to consider the differences of those particular systems.
66The important thing is to decide where the code will run, and to be
67deliberate in your decision.
68
69The material below is separated into three main sections: main issues of
70portability (L<"ISSUES">, platform-specific issues (L<"PLATFORMS">, and
71builtin perl functions that behave differently on various ports
72(L<"FUNCTION IMPLEMENTATIONS">.
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73
74This information should not be considered complete; it includes possibly
b8099c3d 75transient information about idiosyncrasies of some of the ports, almost
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76all of which are in a state of constant evolution. Thus this material
77should be considered a perpetual work in progress
78(E<lt>IMG SRC="yellow_sign.gif" ALT="Under Construction"E<gt>).
79
80
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81
82
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83=head1 ISSUES
84
85=head2 Newlines
86
638bc118 87In most operating systems, lines in files are terminated by newlines.
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88Just what is used as a newline may vary from OS to OS. Unix
89traditionally uses C<\012>, one kind of Windows I/O uses C<\015\012>,
90and S<Mac OS> uses C<\015>.
91
92Perl uses C<\n> to represent the "logical" newline, where what
93is logical may depend on the platform in use. In MacPerl, C<\n>
94always means C<\015>. In DOSish perls, C<\n> usually means C<\012>, but
95when accessing a file in "text" mode, STDIO translates it to (or from)
96C<\015\012>.
97
98Due to the "text" mode translation, DOSish perls have limitations
99of using C<seek> and C<tell> when a file is being accessed in "text"
100mode. Specifically, if you stick to C<seek>-ing to locations you got
101from C<tell> (and no others), you are usually free to use C<seek> and
102C<tell> even in "text" mode. In general, using C<seek> or C<tell> or
103other file operations that count bytes instead of characters, without
104considering the length of C<\n>, may be non-portable. If you use
105C<binmode> on a file, however, you can usually use C<seek> and C<tell>
106with arbitrary values quite safely.
107
108A common misconception in socket programming is that C<\n> eq C<\012>
0a47030a 109everywhere. When using protocols such as common Internet protocols,
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110C<\012> and C<\015> are called for specifically, and the values of
111the logical C<\n> and C<\r> (carriage return) are not reliable.
112
113 print SOCKET "Hi there, client!\r\n"; # WRONG
114 print SOCKET "Hi there, client!\015\012"; # RIGHT
115
116[NOTE: this does not necessarily apply to communications that are
117filtered by another program or module before sending to the socket; the
118the most popular EBCDIC webserver, for instance, accepts C<\r\n>,
119which translates those characters, along with all other
120characters in text streams, from EBCDIC to ASCII.]
121
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122However, using C<\015\012> (or C<\cM\cJ>, or C<\x0D\x0A>) can be tedious
123and unsightly, as well as confusing to those maintaining the code. As
124such, the C<Socket> module supplies the Right Thing for those who want it.
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125
126 use Socket qw(:DEFAULT :crlf);
127 print SOCKET "Hi there, client!$CRLF" # RIGHT
128
129When reading I<from> a socket, remember that the default input record
130separator (C<$/>) is C<\n>, but code like this should recognize C<$/> as
131C<\012> or C<\015\012>:
132
133 while (<SOCKET>) {
134 # ...
135 }
136
137Better:
138
139 use Socket qw(:DEFAULT :crlf);
140 local($/) = LF; # not needed if $/ is already \012
141
142 while (<SOCKET>) {
143 s/$CR?$LF/\n/; # not sure if socket uses LF or CRLF, OK
144 # s/\015?\012/\n/; # same thing
145 }
146
147And this example is actually better than the previous one even for Unix
148platforms, because now any C<\015>'s (C<\cM>'s) are stripped out
149(and there was much rejoicing).
150
151
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152=head2 Numbers endianness and Width
153
154Different CPUs store integers and floating point numbers in different
155orders (called I<endianness>) and widths (32-bit and 64-bit being the
156most common). This affects your programs if they attempt to transfer
157numbers in binary format from a CPU architecture to another over some
158channel: either 'live' via network connections or storing the numbers
159to secondary storage such as a disk file.
160
161Conflicting storage orders make utter mess out of the numbers: if a
162little-endian host (Intel, Alpha) stores 0x12345678 (305419896 in
163decimal), a big-endian host (Motorola, MIPS, Sparc, PA) reads it as
1640x78563412 (2018915346 in decimal). To avoid this problem in network
165(socket) connections use the C<pack()> and C<unpack()> formats C<"n">
166and C<"N">, the "network" orders, they are guaranteed to be portable.
167
168Different widths can cause truncation even between platforms of equal
169endianness: the platform of shorter width loses the upper parts of the
170number. There is no good solution for this problem except to avoid
171transferring or storing raw binary numbers.
172
173One can circumnavigate both these problems in two ways: either
174transfer and store numbers always in text format, instead of raw
175binary, or consider using modules like C<Data::Dumper> (included in
176the standard distribution as of Perl 5.005) and C<Storable>.
177
dd9f0070 178=head2 Files
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179
180Most platforms these days structure files in a hierarchical fashion.
181So, it is reasonably safe to assume that any platform supports the
182notion of a "path" to uniquely identify a file on the system. Just
183how that path is actually written, differs.
184
185While they are similar, file path specifications differ between Unix,
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186Windows, S<Mac OS>, OS/2, VMS, VOS, S<RISC OS> and probably others.
187Unix, for example, is one of the few OSes that has the idea of a single
188root directory.
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189
190VMS, Windows, and OS/2 can work similarly to Unix with C</> as path
191separator, or in their own idiosyncratic ways (such as having several
495c5fdc 192root directories and various "unrooted" device files such NIL: and
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193LPT:).
194
195S<Mac OS> uses C<:> as a path separator instead of C</>.
196
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197VOS perl can emulate Unix filenames with C</> as path separator. The
198native pathname characters greater-than, less-than, number-sign, and
199percent-sign are always accepted.
200
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201C<RISC OS> perl can emulate Unix filenames with C</> as path
202separator, or go native and use C<.> for path separator and C<:> to
203signal filing systems and disc names.
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204
205As with the newline problem above, there are modules that can help. The
206C<File::Spec> modules provide methods to do the Right Thing on whatever
207platform happens to be running the program.
208
209 use File::Spec;
210 chdir(File::Spec->updir()); # go up one directory
211 $file = File::Spec->catfile(
212 File::Spec->curdir(), 'temp', 'file.txt'
213 );
214 # on Unix and Win32, './temp/file.txt'
215 # on Mac OS, ':temp:file.txt'
216
217File::Spec is available in the standard distribution, as of version
2185.004_05.
219
220In general, production code should not have file paths hardcoded; making
221them user supplied or from a configuration file is better, keeping in mind
222that file path syntax varies on different machines.
223
224This is especially noticeable in scripts like Makefiles and test suites,
225which often assume C</> as a path separator for subdirectories.
226
227Also of use is C<File::Basename>, from the standard distribution, which
228splits a pathname into pieces (base filename, full path to directory,
229and file suffix).
230
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231Even when on a single platform (if you can call UNIX a single
232platform), remember not to count on the existence or the contents of
233system-specific files, like F</etc/passwd>, F</etc/sendmail.conf>, or
234F</etc/resolv.conf>. For example the F</etc/passwd> may exist but it
235may not contain the encrypted passwords because the system is using
236some form of enhanced security-- or it may not contain all the
237accounts because the system is using NIS. If code does need to rely
238on such a file, include a description of the file and its format in
239the code's documentation, and make it easy for the user to override
240the default location of the file.
e41182b5 241
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242Do not have two files of the same name with different case, like
243F<test.pl> and <Test.pl>, as many platforms have case-insensitive
244filenames. Also, try not to have non-word characters (except for C<.>)
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245in the names, and keep them to the 8.3 convention, for maximum
246portability.
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247
248Likewise, if using C<AutoSplit>, try to keep the split functions to
2498.3 naming and case-insensitive conventions; or, at the very least,
250make it so the resulting files have a unique (case-insensitively)
251first 8 characters.
252
0a47030a 253Don't assume C<E<lt>> won't be the first character of a filename. Always
ae6c4aac 254use C<E<lt>> explicitly to open a file for reading:
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255
256 open(FILE, "<$existing_file") or die $!;
257
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258
259=head2 System Interaction
260
261Not all platforms provide for the notion of a command line, necessarily.
262These are usually platforms that rely on a Graphical User Interface (GUI)
263for user interaction. So a program requiring command lines might not work
264everywhere. But this is probably for the user of the program to deal
265with.
266
267Some platforms can't delete or rename files that are being held open by
268the system. Remember to C<close> files when you are done with them.
269Don't C<unlink> or C<rename> an open file. Don't C<tie> to or C<open> a
270file that is already tied to or opened; C<untie> or C<close> first.
271
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272Don't open the same file more than once at a time for writing, as some
273operating systems put mandatory locks on such files.
274
e41182b5 275Don't count on a specific environment variable existing in C<%ENV>.
0a47030a 276Don't count on C<%ENV> entries being case-sensitive, or even
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277case-preserving.
278
0a47030a 279Don't count on signals.
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280
281Don't count on filename globbing. Use C<opendir>, C<readdir>, and
282C<closedir> instead.
283
b8099c3d 284Don't count on per-program environment variables, or per-program current
dd9f0070 285directories.
b8099c3d 286
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287
288=head2 Interprocess Communication (IPC)
289
290In general, don't directly access the system in code that is meant to be
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291portable. That means, no C<system>, C<exec>, C<fork>, C<pipe>, C<``>,
292C<qx//>, C<open> with a C<|>, nor any of the other things that makes being
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293a Unix perl hacker worth being.
294
295Commands that launch external processes are generally supported on
296most platforms (though many of them do not support any type of forking),
297but the problem with using them arises from what you invoke with them.
298External tools are often named differently on different platforms, often
299not available in the same location, often accept different arguments,
300often behave differently, and often represent their results in a
301platform-dependent way. Thus you should seldom depend on them to produce
302consistent results.
303
304One especially common bit of Perl code is opening a pipe to sendmail:
305
306 open(MAIL, '|/usr/lib/sendmail -t') or die $!;
307
308This is fine for systems programming when sendmail is known to be
309available. But it is not fine for many non-Unix systems, and even
310some Unix systems that may not have sendmail installed. If a portable
311solution is needed, see the C<Mail::Send> and C<Mail::Mailer> modules
312in the C<MailTools> distribution. C<Mail::Mailer> provides several
313mailing methods, including mail, sendmail, and direct SMTP
314(via C<Net::SMTP>) if a mail transfer agent is not available.
315
316The rule of thumb for portable code is: Do it all in portable Perl, or
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317use a module (that may internally implement it with platform-specific
318code, but expose a common interface).
e41182b5 319
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320The UNIX System V IPC (C<msg*(), sem*(), shm*()>) is not available
321even in all UNIX platforms.
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322
323=head2 External Subroutines (XS)
324
325XS code, in general, can be made to work with any platform; but dependent
326libraries, header files, etc., might not be readily available or
327portable, or the XS code itself might be platform-specific, just as Perl
328code might be. If the libraries and headers are portable, then it is
329normally reasonable to make sure the XS code is portable, too.
330
331There is a different kind of portability issue with writing XS
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332code: availability of a C compiler on the end-user's system. C brings
333with it its own portability issues, and writing XS code will expose you to
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334some of those. Writing purely in perl is a comparatively easier way to
335achieve portability.
336
337
338=head2 Standard Modules
339
340In general, the standard modules work across platforms. Notable
341exceptions are C<CPAN.pm> (which currently makes connections to external
342programs that may not be available), platform-specific modules (like
343C<ExtUtils::MM_VMS>), and DBM modules.
344
345There is no one DBM module that is available on all platforms.
346C<SDBM_File> and the others are generally available on all Unix and DOSish
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347ports, but not in MacPerl, where only C<NBDM_File> and C<DB_File> are
348available.
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349
350The good news is that at least some DBM module should be available, and
351C<AnyDBM_File> will use whichever module it can find. Of course, then
352the code needs to be fairly strict, dropping to the lowest common
353denominator (e.g., not exceeding 1K for each record).
354
355
356=head2 Time and Date
357
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358The system's notion of time of day and calendar date is controlled in
359widely different ways. Don't assume the timezone is stored in C<$ENV{TZ}>,
360and even if it is, don't assume that you can control the timezone through
361that variable.
e41182b5 362
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363Don't assume that the epoch starts at 00:00:00, January 1, 1970,
364because that is OS-specific. Better to store a date in an unambiguous
365representation. The ISO 8601 standard defines YYYY-MM-DD as the date
366format. A text representation (like C<1 Jan 1970>) can be easily
367converted into an OS-specific value using a module like
368C<Date::Parse>. An array of values, such as those returned by
369C<localtime>, can be converted to an OS-specific representation using
370C<Time::Local>.
371
372
373=head2 Character sets and character encoding
374
375Assume very little about character sets. Do not assume anything about
376the numerical values (C<ord()>, C<chr()>) of characters. Do not
377assume that the alphabetic characters are encoded contiguously (in
378numerical sense). Do no assume anything about the ordering of the
379characters. The lowercase letters may come before or after the
380uppercase letters, the lowercase and uppercase may be interlaced so
b1ff3570 381that both 'a' and 'A' come before the 'b', the accented and other
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382international characters may be interlaced so that E<auml> comes
383before the 'b'.
384
385
386=head2 Internationalisation
387
388If you may assume POSIX (a rather large assumption, that: in practise
389that means UNIX) you may read more about the POSIX locale system from
390L<perllocale>. The locale system at least attempts to make things a
391little bit more portable or at least more convenient and
392native-friendly for non-English users. The system affects character
393sets and encoding, and date and time formatting, among other things.
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394
395
396=head2 System Resources
397
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398If your code is destined for systems with severely constrained (or
399missing!) virtual memory systems then you want to be I<especially> mindful
400of avoiding wasteful constructs such as:
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401
402 # NOTE: this is no longer "bad" in perl5.005
403 for (0..10000000) {} # bad
404 for (my $x = 0; $x <= 10000000; ++$x) {} # good
405
406 @lines = <VERY_LARGE_FILE>; # bad
407
408 while (<FILE>) {$file .= $_} # sometimes bad
0a47030a 409 $file = join('', <FILE>); # better
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410
411The last two may appear unintuitive to most people. The first of those
412two constructs repeatedly grows a string, while the second allocates a
413large chunk of memory in one go. On some systems, the latter is more
414efficient that the former.
415
0a47030a 416
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417=head2 Security
418
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419Most multi-user platforms provide basic levels of security that is usually
420felt at the file-system level. Other platforms usually don't
421(unfortunately). Thus the notion of user id, or "home" directory, or even
422the state of being logged-in, may be unrecognizable on many platforms. If
423you write programs that are security conscious, it is usually best to know
424what type of system you will be operating under, and write code explicitly
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425for that platform (or class of platforms).
426
0a47030a 427
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428=head2 Style
429
430For those times when it is necessary to have platform-specific code,
431consider keeping the platform-specific code in one place, making porting
432to other platforms easier. Use the C<Config> module and the special
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433variable C<$^O> to differentiate platforms, as described in
434L<"PLATFORMS">.
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435
436
0a47030a 437=head1 CPAN Testers
e41182b5 438
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439Modules uploaded to CPAN are tested by a variety of volunteers on
440different platforms. These CPAN testers are notified by mail of each
e41182b5 441new upload, and reply to the list with PASS, FAIL, NA (not applicable to
0a47030a 442this platform), or UNKNOWN (unknown), along with any relevant notations.
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443
444The purpose of the testing is twofold: one, to help developers fix any
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445problems in their code that crop up because of lack of testing on other
446platforms; two, to provide users with information about whether or not
447a given module works on a given platform.
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448
449=over 4
450
451=item Mailing list: cpan-testers@perl.org
452
453=item Testing results: C<http://www.connect.net/gbarr/cpan-test/>
454
455=back
456
457
458=head1 PLATFORMS
459
460As of version 5.002, Perl is built with a C<$^O> variable that
461indicates the operating system it was built on. This was implemented
462to help speed up code that would otherwise have to C<use Config;> and
463use the value of C<$Config{'osname'}>. Of course, to get
464detailed information about the system, looking into C<%Config> is
465certainly recommended.
466
467=head2 Unix
468
469Perl works on a bewildering variety of Unix and Unix-like platforms (see
470e.g. most of the files in the F<hints/> directory in the source code kit).
471On most of these systems, the value of C<$^O> (hence C<$Config{'osname'}>,
472too) is determined by lowercasing and stripping punctuation from the first
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473field of the string returned by typing C<uname -a> (or a similar command)
474at the shell prompt. Here, for example, are a few of the more popular
475Unix flavors:
e41182b5 476
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477 uname $^O $Config{'archname'}
478 -------------------------------------------
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479 AIX aix aix
480 FreeBSD freebsd freebsd-i386
481 Linux linux i386-linux
482 HP-UX hpux PA-RISC1.1
483 IRIX irix irix
484 OSF1 dec_osf alpha-dec_osf
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485 SunOS solaris sun4-solaris
486 SunOS solaris i86pc-solaris
322422de 487 SunOS4 sunos sun4-sunos
e41182b5 488
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489Note that because the C<$Config{'archname'}> may depend on the hardware
490architecture it may vary quite a lot, much more than the C<$^O>.
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491
492=head2 DOS and Derivatives
493
494Perl has long been ported to PC style microcomputers running under
495systems like PC-DOS, MS-DOS, OS/2, and most Windows platforms you can
496bring yourself to mention (except for Windows CE, if you count that).
497Users familiar with I<COMMAND.COM> and/or I<CMD.EXE> style shells should
498be aware that each of these file specifications may have subtle
499differences:
500
501 $filespec0 = "c:/foo/bar/file.txt";
502 $filespec1 = "c:\\foo\\bar\\file.txt";
503 $filespec2 = 'c:\foo\bar\file.txt';
504 $filespec3 = 'c:\\foo\\bar\\file.txt';
505
506System calls accept either C</> or C<\> as the path separator. However,
507many command-line utilities of DOS vintage treat C</> as the option
508prefix, so they may get confused by filenames containing C</>. Aside
509from calling any external programs, C</> will work just fine, and
510probably better, as it is more consistent with popular usage, and avoids
511the problem of remembering what to backwhack and what not to.
512
0a47030a 513The DOS FAT filesystem can only accommodate "8.3" style filenames. Under
e41182b5 514the "case insensitive, but case preserving" HPFS (OS/2) and NTFS (NT)
0a47030a 515filesystems you may have to be careful about case returned with functions
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516like C<readdir> or used with functions like C<open> or C<opendir>.
517
518DOS also treats several filenames as special, such as AUX, PRN, NUL, CON,
519COM1, LPT1, LPT2 etc. Unfortunately these filenames won't even work
520if you include an explicit directory prefix, in some cases. It is best
521to avoid such filenames, if you want your code to be portable to DOS
522and its derivatives.
523
524Users of these operating systems may also wish to make use of
525scripts such as I<pl2bat.bat> or I<pl2cmd> as appropriate to
526put wrappers around your scripts.
527
528Newline (C<\n>) is translated as C<\015\012> by STDIO when reading from
529and writing to files. C<binmode(FILEHANDLE)> will keep C<\n> translated
530as C<\012> for that filehandle. Since it is a noop on other systems,
531C<binmode> should be used for cross-platform code that deals with binary
532data.
533
534The C<$^O> variable and the C<$Config{'archname'}> values for various
535DOSish perls are as follows:
536
537 OS $^O $Config{'archname'}
538 --------------------------------------------
539 MS-DOS dos
540 PC-DOS dos
541 OS/2 os2
542 Windows 95 MSWin32 MSWin32-x86
543 Windows NT MSWin32 MSWin32-x86
544 Windows NT MSWin32 MSWin32-alpha
545 Windows NT MSWin32 MSWin32-ppc
546
547Also see:
548
549=over 4
550
551=item The djgpp environment for DOS, C<http://www.delorie.com/djgpp/>
552
553=item The EMX environment for DOS, OS/2, etc. C<emx@iaehv.nl>,
554C<http://www.juge.com/bbs/Hobb.19.html>
555
556=item Build instructions for Win32, L<perlwin32>.
557
558=item The ActiveState Pages, C<http://www.activestate.com/>
559
560=back
561
562
dd9f0070 563=head2 S<Mac OS>
e41182b5
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564
565Any module requiring XS compilation is right out for most people, because
566MacPerl is built using non-free (and non-cheap!) compilers. Some XS
567modules that can work with MacPerl are built and distributed in binary
0a47030a
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568form on CPAN. See I<MacPerl: Power and Ease> and L<"CPAN Testers">
569for more details.
e41182b5
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570
571Directories are specified as:
572
573 volume:folder:file for absolute pathnames
574 volume:folder: for absolute pathnames
575 :folder:file for relative pathnames
576 :folder: for relative pathnames
577 :file for relative pathnames
578 file for relative pathnames
579
580Files in a directory are stored in alphabetical order. Filenames are
581limited to 31 characters, and may include any character except C<:>,
582which is reserved as a path separator.
583
0a47030a
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584Instead of C<flock>, see C<FSpSetFLock> and C<FSpRstFLock> in the
585C<Mac::Files> module.
e41182b5
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586
587In the MacPerl application, you can't run a program from the command line;
588programs that expect C<@ARGV> to be populated can be edited with something
589like the following, which brings up a dialog box asking for the command
590line arguments.
591
592 if (!@ARGV) {
593 @ARGV = split /\s+/, MacPerl::Ask('Arguments?');
594 }
595
596A MacPerl script saved as a droplet will populate C<@ARGV> with the full
597pathnames of the files dropped onto the script.
598
599Mac users can use programs on a kind of command line under MPW (Macintosh
600Programmer's Workshop, a free development environment from Apple).
601MacPerl was first introduced as an MPW tool, and MPW can be used like a
602shell:
603
604 perl myscript.plx some arguments
605
606ToolServer is another app from Apple that provides access to MPW tools
0a47030a 607from MPW and the MacPerl app, which allows MacPerl programs to use
e41182b5
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608C<system>, backticks, and piped C<open>.
609
610"S<Mac OS>" is the proper name for the operating system, but the value
611in C<$^O> is "MacOS". To determine architecture, version, or whether
612the application or MPW tool version is running, check:
613
614 $is_app = $MacPerl::Version =~ /App/;
615 $is_tool = $MacPerl::Version =~ /MPW/;
616 ($version) = $MacPerl::Version =~ /^(\S+)/;
617 $is_ppc = $MacPerl::Architecture eq 'MacPPC';
618 $is_68k = $MacPerl::Architecture eq 'Mac68K';
619
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620S<Mac OS X>, to be based on NeXT's OpenStep OS, will be able to run
621MacPerl natively (in the Blue Box, and even in the Yellow Box, once some
622changes to the toolbox calls are made), but Unix perl will also run
623natively.
e41182b5
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624
625Also see:
626
627=over 4
628
629=item The MacPerl Pages, C<http://www.ptf.com/macperl/>.
630
631=item The MacPerl mailing list, C<mac-perl-request@iis.ee.ethz.ch>.
632
633=back
634
635
636=head2 VMS
637
638Perl on VMS is discussed in F<vms/perlvms.pod> in the perl distribution.
0a47030a 639Note that perl on VMS can accept either VMS- or Unix-style file
e41182b5
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640specifications as in either of the following:
641
642 $ perl -ne "print if /perl_setup/i" SYS$LOGIN:LOGIN.COM
643 $ perl -ne "print if /perl_setup/i" /sys$login/login.com
644
645but not a mixture of both as in:
646
647 $ perl -ne "print if /perl_setup/i" sys$login:/login.com
648 Can't open sys$login:/login.com: file specification syntax error
649
650Interacting with Perl from the Digital Command Language (DCL) shell
651often requires a different set of quotation marks than Unix shells do.
652For example:
653
654 $ perl -e "print ""Hello, world.\n"""
655 Hello, world.
656
657There are a number of ways to wrap your perl scripts in DCL .COM files if
658you are so inclined. For example:
659
660 $ write sys$output "Hello from DCL!"
661 $ if p1 .eqs. ""
662 $ then perl -x 'f$environment("PROCEDURE")
663 $ else perl -x - 'p1 'p2 'p3 'p4 'p5 'p6 'p7 'p8
664 $ deck/dollars="__END__"
665 #!/usr/bin/perl
666
667 print "Hello from Perl!\n";
668
669 __END__
670 $ endif
671
672Do take care with C<$ ASSIGN/nolog/user SYS$COMMAND: SYS$INPUT> if your
673perl-in-DCL script expects to do things like C<$read = E<lt>STDINE<gt>;>.
674
675Filenames are in the format "name.extension;version". The maximum
676length for filenames is 39 characters, and the maximum length for
677extensions is also 39 characters. Version is a number from 1 to
67832767. Valid characters are C</[A-Z0-9$_-]/>.
679
680VMS' RMS filesystem is case insensitive and does not preserve case.
681C<readdir> returns lowercased filenames, but specifying a file for
b8099c3d 682opening remains case insensitive. Files without extensions have a
e41182b5 683trailing period on them, so doing a C<readdir> with a file named F<A.;5>
0a47030a
GS
684will return F<a.> (though that file could be opened with
685C<open(FH, 'A')>).
e41182b5 686
f34d0673 687RMS had an eight level limit on directory depths from any rooted logical
dd9f0070
CN
688(allowing 16 levels overall) prior to VMS 7.2. Hence
689C<PERL_ROOT:[LIB.2.3.4.5.6.7.8]> is a valid directory specification but
690C<PERL_ROOT:[LIB.2.3.4.5.6.7.8.9]> is not. F<Makefile.PL> authors might
691have to take this into account, but at least they can refer to the former
f34d0673 692as C</PERL_ROOT/lib/2/3/4/5/6/7/8/>.
e41182b5 693
0a47030a
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694The C<VMS::Filespec> module, which gets installed as part of the build
695process on VMS, is a pure Perl module that can easily be installed on
696non-VMS platforms and can be helpful for conversions to and from RMS
697native formats.
e41182b5
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698
699What C<\n> represents depends on the type of file that is open. It could
700be C<\015>, C<\012>, C<\015\012>, or nothing. Reading from a file
701translates newlines to C<\012>, unless C<binmode> was executed on that
702handle, just like DOSish perls.
703
704TCP/IP stacks are optional on VMS, so socket routines might not be
705implemented. UDP sockets may not be supported.
706
707The value of C<$^O> on OpenVMS is "VMS". To determine the architecture
708that you are running on without resorting to loading all of C<%Config>
709you can examine the content of the C<@INC> array like so:
710
711 if (grep(/VMS_AXP/, @INC)) {
712 print "I'm on Alpha!\n";
713 } elsif (grep(/VMS_VAX/, @INC)) {
714 print "I'm on VAX!\n";
715 } else {
716 print "I'm not so sure about where $^O is...\n";
717 }
718
719Also see:
720
721=over 4
722
723=item L<perlvms.pod>
724
725=item vmsperl list, C<vmsperl-request@newman.upenn.edu>
726
727Put words C<SUBSCRIBE VMSPERL> in message body.
728
729=item vmsperl on the web, C<http://www.sidhe.org/vmsperl/index.html>
730
731=back
732
733
495c5fdc
GP
734=head2 VOS
735
736Perl on VOS is discussed in F<README.vos> in the perl distribution.
737Note that perl on VOS can accept either VOS- or Unix-style file
738specifications as in either of the following:
739
740 $ perl -ne "print if /perl_setup/i" >system>notices
741 $ perl -ne "print if /perl_setup/i" /system/notices
742
743or even a mixture of both as in:
744
745 $ perl -ne "print if /perl_setup/i" >system/notices
746
747Note that even though VOS allows the slash character to appear in object
748names, because the VOS port of Perl interprets it as a pathname
749delimiting character, VOS files, directories, or links whose names
750contain a slash character cannot be processed. Such files must be
751renamed before they can be processed by Perl.
752
753The following C functions are unimplemented on VOS, any any attempt by
754Perl to use them will result in a fatal error message and an immediate
755exit from Perl: dup, do_aspawn, do_spawn, execlp, execl, execvp, fork,
756waitpid. Once these functions become available in the VOS POSIX.1
757implementation, you can either recompile and rebind Perl, or you can
758download a newer port from ftp.stratus.com.
759
760The value of C<$^O> on VOS is "VOS". To determine the architecture that
761you are running on without resorting to loading all of C<%Config> you
762can examine the content of the C<@INC> array like so:
763
764 if (grep(/VOS/, @INC)) {
765 print "I'm on a Stratus box!\n";
766 } else {
767 print "I'm not on a Stratus box!\n";
768 die;
769 }
770
771 if (grep(/860/, @INC)) {
772 print "This box is a Stratus XA/R!\n";
773 } elsif (grep(/7100/, @INC)) {
774 print "This box is a Stratus HP 7100 or 8000!\n";
775 } elsif (grep(/8000/, @INC)) {
776 print "This box is a Stratus HP 8000!\n";
777 } else {
778 print "This box is a Stratus 68K...\n";
779 }
780
781Also see:
782
783=over 4
784
785=item L<README.vos>
786
787=item VOS mailing list
788
789There is no specific mailing list for Perl on VOS. You can post
790comments to the comp.sys.stratus newsgroup, or subscribe to the general
791Stratus mailing list. Send a letter with "Subscribe Info-Stratus" in
792the message body to majordomo@list.stratagy.com.
793
794=item VOS Perl on the web at C<http://ftp.stratus.com/pub/vos/vos.html>
795
796=back
797
798
e41182b5
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799=head2 EBCDIC Platforms
800
801Recent versions of Perl have been ported to platforms such as OS/400 on
7c5ffed3
JH
802AS/400 minicomputers as well as OS/390 & VM/ESA for IBM Mainframes. Such
803computers use EBCDIC character sets internally (usually Character Code
804Set ID 00819 for OS/400 and IBM-1047 for OS/390 & VM/ESA). Note that on
805the mainframe perl currently works under the "Unix system services
806for OS/390" (formerly known as OpenEdition) and VM/ESA OpenEdition.
e41182b5 807
7c5ffed3
JH
808As of R2.5 of USS for OS/390 and Version 2.3 of VM/ESA these Unix
809sub-systems do not support the C<#!> shebang trick for script invocation.
810Hence, on OS/390 and VM/ESA perl scripts can be executed with a header
811similar to the following simple script:
e41182b5
GS
812
813 : # use perl
814 eval 'exec /usr/local/bin/perl -S $0 ${1+"$@"}'
815 if 0;
816 #!/usr/local/bin/perl # just a comment really
817
818 print "Hello from perl!\n";
819
820On these platforms, bear in mind that the EBCDIC character set may have
0a47030a
GS
821an effect on what happens with some perl functions (such as C<chr>,
822C<pack>, C<print>, C<printf>, C<ord>, C<sort>, C<sprintf>, C<unpack>), as
823well as bit-fiddling with ASCII constants using operators like C<^>, C<&>
824and C<|>, not to mention dealing with socket interfaces to ASCII computers
b687b08b 825(see L<Newlines>).
e41182b5
GS
826
827Fortunately, most web servers for the mainframe will correctly translate
828the C<\n> in the following statement to its ASCII equivalent (note that
7c5ffed3 829C<\r> is the same under both Unix and OS/390 & VM/ESA):
e41182b5
GS
830
831 print "Content-type: text/html\r\n\r\n";
832
833The value of C<$^O> on OS/390 is "os390".
834
7c5ffed3 835The value of C<$^O> on VM/ESA is "vmesa".
e41182b5
GS
836Some simple tricks for determining if you are running on an EBCDIC
837platform could include any of the following (perhaps all):
838
839 if ("\t" eq "\05") { print "EBCDIC may be spoken here!\n"; }
840
841 if (ord('A') == 193) { print "EBCDIC may be spoken here!\n"; }
842
843 if (chr(169) eq 'z') { print "EBCDIC may be spoken here!\n"; }
844
845Note that one thing you may not want to rely on is the EBCDIC encoding
0a47030a
GS
846of punctuation characters since these may differ from code page to code
847page (and once your module or script is rumoured to work with EBCDIC,
848folks will want it to work with all EBCDIC character sets).
e41182b5
GS
849
850Also see:
851
852=over 4
853
854=item perl-mvs list
855
856The perl-mvs@perl.org list is for discussion of porting issues as well as
857general usage issues for all EBCDIC Perls. Send a message body of
858"subscribe perl-mvs" to majordomo@perl.org.
859
0a47030a 860=item AS/400 Perl information at C<http://as400.rochester.ibm.com/>
e41182b5
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861
862=back
863
b8099c3d
CN
864
865=head2 Acorn RISC OS
866
0a47030a
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867As Acorns use ASCII with newlines (C<\n>) in text files as C<\012> like
868Unix and Unix filename emulation is turned on by default, it is quite
869likely that most simple scripts will work "out of the box". The native
870filing system is modular, and individual filing systems are free to be
871case-sensitive or insensitive, and are usually case-preserving. Some
872native filing systems have name length limits which file and directory
873names are silently truncated to fit - scripts should be aware that the
874standard disc filing system currently has a name length limit of B<10>
875characters, with up to 77 items in a directory, but other filing systems
876may not impose such limitations.
b8099c3d
CN
877
878Native filenames are of the form
879
880 Filesystem#Special_Field::DiscName.$.Directory.Directory.File
dd9f0070 881
b8099c3d
CN
882where
883
884 Special_Field is not usually present, but may contain . and $ .
885 Filesystem =~ m|[A-Za-z0-9_]|
886 DsicName =~ m|[A-Za-z0-9_/]|
887 $ represents the root directory
888 . is the path separator
889 @ is the current directory (per filesystem but machine global)
890 ^ is the parent directory
891 Directory and File =~ m|[^\0- "\.\$\%\&:\@\\^\|\177]+|
892
893The default filename translation is roughly C<tr|/.|./|;>
894
895Note that C<"ADFS::HardDisc.$.File" ne 'ADFS::HardDisc.$.File'> and that
0a47030a
GS
896the second stage of C<$> interpolation in regular expressions will fall
897foul of the C<$.> if scripts are not careful.
898
899Logical paths specified by system variables containing comma-separated
900search lists are also allowed, hence C<System:Modules> is a valid
901filename, and the filesystem will prefix C<Modules> with each section of
902C<System$Path> until a name is made that points to an object on disc.
903Writing to a new file C<System:Modules> would only be allowed if
904C<System$Path> contains a single item list. The filesystem will also
905expand system variables in filenames if enclosed in angle brackets, so
906C<E<lt>System$DirE<gt>.Modules> would look for the file
907S<C<$ENV{'System$Dir'} . 'Modules'>>. The obvious implication of this is
908that B<fully qualified filenames can start with C<E<lt>E<gt>> and should
909be protected when C<open> is used for input.
b8099c3d
CN
910
911Because C<.> was in use as a directory separator and filenames could not
912be assumed to be unique after 10 characters, Acorn implemented the C
913compiler to strip the trailing C<.c> C<.h> C<.s> and C<.o> suffix from
914filenames specified in source code and store the respective files in
915subdirectories named after the suffix. Hence files are translated:
916
917 foo.h h.foo
918 C:foo.h C:h.foo (logical path variable)
919 sys/os.h sys.h.os (C compiler groks Unix-speak)
920 10charname.c c.10charname
921 10charname.o o.10charname
922 11charname_.c c.11charname (assuming filesystem truncates at 10)
923
924The Unix emulation library's translation of filenames to native assumes
0a47030a
GS
925that this sort of translation is required, and allows a user defined list
926of known suffixes which it will transpose in this fashion. This may
927appear transparent, but consider that with these rules C<foo/bar/baz.h>
928and C<foo/bar/h/baz> both map to C<foo.bar.h.baz>, and that C<readdir> and
929C<glob> cannot and do not attempt to emulate the reverse mapping. Other
930C<.>s in filenames are translated to C</>.
931
932As implied above the environment accessed through C<%ENV> is global, and
933the convention is that program specific environment variables are of the
934form C<Program$Name>. Each filing system maintains a current directory,
935and the current filing system's current directory is the B<global> current
936directory. Consequently, sociable scripts don't change the current
937directory but rely on full pathnames, and scripts (and Makefiles) cannot
938assume that they can spawn a child process which can change the current
939directory without affecting its parent (and everyone else for that
940matter).
941
942As native operating system filehandles are global and currently are
943allocated down from 255, with 0 being a reserved value the Unix emulation
944library emulates Unix filehandles. Consequently, you can't rely on
945passing C<STDIN>, C<STDOUT>, or C<STDERR> to your children.
946
947The desire of users to express filenames of the form
948C<E<lt>Foo$DirE<gt>.Bar> on the command line unquoted causes problems,
949too: C<``> command output capture has to perform a guessing game. It
950assumes that a string C<E<lt>[^E<lt>E<gt>]+\$[^E<lt>E<gt>]E<gt>> is a
951reference to an environment variable, whereas anything else involving
952C<E<lt>> or C<E<gt>> is redirection, and generally manages to be 99%
953right. Of course, the problem remains that scripts cannot rely on any
954Unix tools being available, or that any tools found have Unix-like command
955line arguments.
956
957Extensions and XS are, in theory, buildable by anyone using free tools.
958In practice, many don't, as users of the Acorn platform are used to binary
959distribution. MakeMaker does run, but no available make currently copes
960with MakeMaker's makefiles; even if/when this is fixed, the lack of a
961Unix-like shell can cause problems with makefile rules, especially lines
962of the form C<cd sdbm && make all>, and anything using quoting.
b8099c3d
CN
963
964"S<RISC OS>" is the proper name for the operating system, but the value
965in C<$^O> is "riscos" (because we don't like shouting).
966
967Also see:
968
969=over 4
970
971=item perl list
972
973=back
974
975
e41182b5
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976=head2 Other perls
977
b8099c3d
CN
978Perl has been ported to a variety of platforms that do not fit into any of
979the above categories. Some, such as AmigaOS, BeOS, QNX, and Plan 9, have
0a47030a 980been well-integrated into the standard Perl source code kit. You may need
b8099c3d 981to see the F<ports/> directory on CPAN for information, and possibly
0a47030a
GS
982binaries, for the likes of: aos, atari, lynxos, riscos, Tandem Guardian,
983vos, I<etc.> (yes we know that some of these OSes may fall under the Unix
984category, but we are not a standards body.)
e41182b5
GS
985
986See also:
987
988=over 4
989
990=item Atari, Guido Flohr's page C<http://stud.uni-sb.de/~gufl0000/>
991
992=item HP 300 MPE/iX C<http://www.cccd.edu/~markb/perlix.html>
993
994=item Novell Netware
995
0a47030a 996A free perl5-based PERL.NLM for Novell Netware is available from
e41182b5
GS
997C<http://www.novell.com/>
998
999=back
1000
1001
1002=head1 FUNCTION IMPLEMENTATIONS
1003
1004Listed below are functions unimplemented or implemented differently on
1005various platforms. Following each description will be, in parentheses, a
1006list of platforms that the description applies to.
1007
1008The list may very well be incomplete, or wrong in some places. When in
1009doubt, consult the platform-specific README files in the Perl source
1010distribution, and other documentation resources for a given port.
1011
0a47030a 1012Be aware, moreover, that even among Unix-ish systems there are variations.
e41182b5
GS
1013
1014For many functions, you can also query C<%Config>, exported by default
1015from C<Config.pm>. For example, to check if the platform has the C<lstat>
0a47030a
GS
1016call, check C<$Config{'d_lstat'}>. See L<Config.pm> for a full
1017description of available variables.
e41182b5
GS
1018
1019
1020=head2 Alphabetical Listing of Perl Functions
1021
1022=over 8
1023
1024=item -X FILEHANDLE
1025
1026=item -X EXPR
1027
1028=item -X
1029
1030C<-r>, C<-w>, and C<-x> have only a very limited meaning; directories
1031and applications are executable, and there are no uid/gid
1032considerations. C<-o> is not supported. (S<Mac OS>)
1033
1034C<-r>, C<-w>, C<-x>, and C<-o> tell whether or not file is accessible,
1035which may not reflect UIC-based file protections. (VMS)
1036
b8099c3d
CN
1037C<-s> returns the size of the data fork, not the total size of data fork
1038plus resource fork. (S<Mac OS>).
1039
1040C<-s> by name on an open file will return the space reserved on disk,
1041rather than the current extent. C<-s> on an open filehandle returns the
1042current size. (S<RISC OS>)
1043
e41182b5 1044C<-R>, C<-W>, C<-X>, C<-O> are indistinguishable from C<-r>, C<-w>,
b8099c3d 1045C<-x>, C<-o>. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5
GS
1046
1047C<-b>, C<-c>, C<-k>, C<-g>, C<-p>, C<-u>, C<-A> are not implemented.
1048(S<Mac OS>)
1049
1050C<-g>, C<-k>, C<-l>, C<-p>, C<-u>, C<-A> are not particularly meaningful.
b8099c3d 1051(Win32, VMS, S<RISC OS>)
e41182b5
GS
1052
1053C<-d> is true if passed a device spec without an explicit directory.
1054(VMS)
1055
1056C<-T> and C<-B> are implemented, but might misclassify Mac text files
0a47030a
GS
1057with foreign characters; this is the case will all platforms, but may
1058affect S<Mac OS> often. (S<Mac OS>)
e41182b5
GS
1059
1060C<-x> (or C<-X>) determine if a file ends in one of the executable
1061suffixes. C<-S> is meaningless. (Win32)
1062
b8099c3d
CN
1063C<-x> (or C<-X>) determine if a file has an executable file type.
1064(S<RISC OS>)
1065
e41182b5
GS
1066=item binmode FILEHANDLE
1067
b8099c3d 1068Meaningless. (S<Mac OS>, S<RISC OS>)
e41182b5
GS
1069
1070Reopens file and restores pointer; if function fails, underlying
1071filehandle may be closed, or pointer may be in a different position.
1072(VMS)
1073
1074The value returned by C<tell> may be affected after the call, and
1075the filehandle may be flushed. (Win32)
1076
1077=item chmod LIST
1078
1079Only limited meaning. Disabling/enabling write permission is mapped to
1080locking/unlocking the file. (S<Mac OS>)
1081
1082Only good for changing "owner" read-write access, "group", and "other"
1083bits are meaningless. (Win32)
1084
b8099c3d
CN
1085Only good for changing "owner" and "other" read-write access. (S<RISC OS>)
1086
495c5fdc
GP
1087Access permissions are mapped onto VOS access-control list changes. (VOS)
1088
e41182b5
GS
1089=item chown LIST
1090
495c5fdc 1091Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>, VOS)
e41182b5
GS
1092
1093Does nothing, but won't fail. (Win32)
1094
1095=item chroot FILENAME
1096
1097=item chroot
1098
7c5ffed3 1099Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>, VOS, VM/ESA)
e41182b5
GS
1100
1101=item crypt PLAINTEXT,SALT
1102
1103May not be available if library or source was not provided when building
b8099c3d 1104perl. (Win32)
e41182b5 1105
495c5fdc
GP
1106Not implemented. (VOS)
1107
e41182b5
GS
1108=item dbmclose HASH
1109
495c5fdc 1110Not implemented. (VMS, Plan9, VOS)
e41182b5
GS
1111
1112=item dbmopen HASH,DBNAME,MODE
1113
495c5fdc 1114Not implemented. (VMS, Plan9, VOS)
e41182b5
GS
1115
1116=item dump LABEL
1117
b8099c3d 1118Not useful. (S<Mac OS>, S<RISC OS>)
e41182b5
GS
1119
1120Not implemented. (Win32)
1121
b8099c3d 1122Invokes VMS debugger. (VMS)
e41182b5
GS
1123
1124=item exec LIST
1125
1126Not implemented. (S<Mac OS>)
1127
7c5ffed3 1128Implemented via Spawn. (VM/ESA)
e41182b5
GS
1129=item fcntl FILEHANDLE,FUNCTION,SCALAR
1130
1131Not implemented. (Win32, VMS)
1132
1133=item flock FILEHANDLE,OPERATION
1134
495c5fdc 1135Not implemented (S<Mac OS>, VMS, S<RISC OS>, VOS).
e41182b5
GS
1136
1137Available only on Windows NT (not on Windows 95). (Win32)
1138
1139=item fork
1140
7c5ffed3 1141Not implemented. (S<Mac OS>, Win32, AmigaOS, S<RISC OS>, VOS, VM/ESA)
e41182b5
GS
1142
1143=item getlogin
1144
b8099c3d 1145Not implemented. (S<Mac OS>, S<RISC OS>)
e41182b5
GS
1146
1147=item getpgrp PID
1148
495c5fdc 1149Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5
GS
1150
1151=item getppid
1152
b8099c3d 1153Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5
GS
1154
1155=item getpriority WHICH,WHO
1156
7c5ffed3 1157Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
e41182b5
GS
1158
1159=item getpwnam NAME
1160
1161Not implemented. (S<Mac OS>, Win32)
1162
b8099c3d
CN
1163Not useful. (S<RISC OS>)
1164
e41182b5
GS
1165=item getgrnam NAME
1166
b8099c3d 1167Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5
GS
1168
1169=item getnetbyname NAME
1170
1171Not implemented. (S<Mac OS>, Win32, Plan9)
1172
1173=item getpwuid UID
1174
1175Not implemented. (S<Mac OS>, Win32)
1176
b8099c3d
CN
1177Not useful. (S<RISC OS>)
1178
e41182b5
GS
1179=item getgrgid GID
1180
b8099c3d 1181Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5
GS
1182
1183=item getnetbyaddr ADDR,ADDRTYPE
1184
1185Not implemented. (S<Mac OS>, Win32, Plan9)
1186
1187=item getprotobynumber NUMBER
1188
1189Not implemented. (S<Mac OS>)
1190
1191=item getservbyport PORT,PROTO
1192
1193Not implemented. (S<Mac OS>)
1194
1195=item getpwent
1196
7c5ffed3 1197Not implemented. (S<Mac OS>, Win32, VM/ESA)
e41182b5
GS
1198
1199=item getgrent
1200
7c5ffed3 1201Not implemented. (S<Mac OS>, Win32, VMS, VM/ESA)
e41182b5
GS
1202
1203=item gethostent
1204
1205Not implemented. (S<Mac OS>, Win32)
1206
1207=item getnetent
1208
1209Not implemented. (S<Mac OS>, Win32, Plan9)
1210
1211=item getprotoent
1212
1213Not implemented. (S<Mac OS>, Win32, Plan9)
1214
1215=item getservent
1216
1217Not implemented. (Win32, Plan9)
1218
1219=item setpwent
1220
b8099c3d 1221Not implemented. (S<Mac OS>, Win32, S<RISC OS>)
e41182b5
GS
1222
1223=item setgrent
1224
b8099c3d 1225Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5
GS
1226
1227=item sethostent STAYOPEN
1228
b8099c3d 1229Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>)
e41182b5
GS
1230
1231=item setnetent STAYOPEN
1232
b8099c3d 1233Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>)
e41182b5
GS
1234
1235=item setprotoent STAYOPEN
1236
b8099c3d 1237Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>)
e41182b5
GS
1238
1239=item setservent STAYOPEN
1240
b8099c3d 1241Not implemented. (Plan9, Win32, S<RISC OS>)
e41182b5
GS
1242
1243=item endpwent
1244
7c5ffed3 1245Not implemented. (S<Mac OS>, Win32, VM/ESA)
e41182b5
GS
1246
1247=item endgrent
1248
7c5ffed3 1249Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VM/ESA)
e41182b5
GS
1250
1251=item endhostent
1252
1253Not implemented. (S<Mac OS>, Win32)
1254
1255=item endnetent
1256
1257Not implemented. (S<Mac OS>, Win32, Plan9)
1258
1259=item endprotoent
1260
1261Not implemented. (S<Mac OS>, Win32, Plan9)
1262
1263=item endservent
1264
1265Not implemented. (Plan9, Win32)
1266
1267=item getsockopt SOCKET,LEVEL,OPTNAME
1268
1269Not implemented. (S<Mac OS>, Plan9)
1270
1271=item glob EXPR
1272
1273=item glob
1274
1275Globbing built-in, but only C<*> and C<?> metacharacters are supported.
1276(S<Mac OS>)
1277
0a47030a
GS
1278Features depend on external perlglob.exe or perlglob.bat. May be
1279overridden with something like File::DosGlob, which is recommended.
1280(Win32)
e41182b5 1281
b8099c3d 1282Globbing built-in, but only C<*> and C<?> metacharacters are supported.
0a47030a
GS
1283Globbing relies on operating system calls, which may return filenames
1284in any order. As most filesystems are case-insensitive, even "sorted"
1285filenames will not be in case-sensitive order. (S<RISC OS>)
b8099c3d 1286
e41182b5
GS
1287=item ioctl FILEHANDLE,FUNCTION,SCALAR
1288
1289Not implemented. (VMS)
1290
1291Available only for socket handles, and it does what the ioctlsocket() call
1292in the Winsock API does. (Win32)
1293
b8099c3d
CN
1294Available only for socket handles. (S<RISC OS>)
1295
e41182b5
GS
1296=item kill LIST
1297
0a47030a
GS
1298Not implemented, hence not useful for taint checking. (S<Mac OS>,
1299S<RISC OS>)
e41182b5 1300
0a47030a
GS
1301Available only for process handles returned by the C<system(1, ...)>
1302method of spawning a process. (Win32)
e41182b5
GS
1303
1304=item link OLDFILE,NEWFILE
1305
b8099c3d 1306Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5
GS
1307
1308=item lstat FILEHANDLE
1309
1310=item lstat EXPR
1311
1312=item lstat
1313
b8099c3d 1314Not implemented. (VMS, S<RISC OS>)
e41182b5 1315
b8099c3d 1316Return values may be bogus. (Win32)
e41182b5
GS
1317
1318=item msgctl ID,CMD,ARG
1319
1320=item msgget KEY,FLAGS
1321
1322=item msgsnd ID,MSG,FLAGS
1323
1324=item msgrcv ID,VAR,SIZE,TYPE,FLAGS
1325
495c5fdc 1326Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>, VOS)
e41182b5
GS
1327
1328=item open FILEHANDLE,EXPR
1329
1330=item open FILEHANDLE
1331
1332The C<|> variants are only supported if ToolServer is installed.
1333(S<Mac OS>)
1334
b8099c3d 1335open to C<|-> and C<-|> are unsupported. (S<Mac OS>, Win32, S<RISC OS>)
e41182b5
GS
1336
1337=item pipe READHANDLE,WRITEHANDLE
1338
1339Not implemented. (S<Mac OS>)
1340
1341=item readlink EXPR
1342
1343=item readlink
1344
b8099c3d 1345Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5
GS
1346
1347=item select RBITS,WBITS,EBITS,TIMEOUT
1348
1349Only implemented on sockets. (Win32)
1350
b8099c3d
CN
1351Only reliable on sockets. (S<RISC OS>)
1352
e41182b5
GS
1353=item semctl ID,SEMNUM,CMD,ARG
1354
1355=item semget KEY,NSEMS,FLAGS
1356
1357=item semop KEY,OPSTRING
1358
495c5fdc 1359Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5
GS
1360
1361=item setpgrp PID,PGRP
1362
495c5fdc 1363Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5
GS
1364
1365=item setpriority WHICH,WHO,PRIORITY
1366
495c5fdc 1367Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5
GS
1368
1369=item setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL
1370
1371Not implemented. (S<Mac OS>, Plan9)
1372
1373=item shmctl ID,CMD,ARG
1374
1375=item shmget KEY,SIZE,FLAGS
1376
1377=item shmread ID,VAR,POS,SIZE
1378
1379=item shmwrite ID,STRING,POS,SIZE
1380
495c5fdc 1381Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5
GS
1382
1383=item socketpair SOCKET1,SOCKET2,DOMAIN,TYPE,PROTOCOL
1384
7c5ffed3 1385Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
e41182b5
GS
1386
1387=item stat FILEHANDLE
1388
1389=item stat EXPR
1390
1391=item stat
1392
1393mtime and atime are the same thing, and ctime is creation time instead of
1394inode change time. (S<Mac OS>)
1395
1396device and inode are not meaningful. (Win32)
1397
1398device and inode are not necessarily reliable. (VMS)
1399
b8099c3d
CN
1400mtime, atime and ctime all return the last modification time. Device and
1401inode are not necessarily reliable. (S<RISC OS>)
1402
e41182b5
GS
1403=item symlink OLDFILE,NEWFILE
1404
b8099c3d 1405Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5
GS
1406
1407=item syscall LIST
1408
7c5ffed3 1409Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
e41182b5 1410
f34d0673
GS
1411=item sysopen FILEHANDLE,FILENAME,MODE,PERMS
1412
dd9f0070 1413The traditional "0", "1", and "2" MODEs are implemented with different
322422de
GS
1414numeric values on some systems. The flags exported by C<Fcntl>
1415(O_RDONLY, O_WRONLY, O_RDWR) should work everywhere though. (S<Mac
7c5ffed3 1416OS>, OS/390, VM/ESA)
f34d0673 1417
e41182b5
GS
1418=item system LIST
1419
1420Only implemented if ToolServer is installed. (S<Mac OS>)
1421
1422As an optimization, may not call the command shell specified in
1423C<$ENV{PERL5SHELL}>. C<system(1, @args)> spawns an external
1424process and immediately returns its process designator, without
1425waiting for it to terminate. Return value may be used subsequently
1426in C<wait> or C<waitpid>. (Win32)
1427
b8099c3d
CN
1428There is no shell to process metacharacters, and the native standard is
1429to pass a command line terminated by "\n" "\r" or "\0" to the spawned
1430program. Redirection such as C<E<gt> foo> is performed (if at all) by
1431the run time library of the spawned program. C<system> I<list> will call
1432the Unix emulation library's C<exec> emulation, which attempts to provide
1433emulation of the stdin, stdout, stderr in force in the parent, providing
1434the child program uses a compatible version of the emulation library.
1435I<scalar> will call the native command line direct and no such emulation
1436of a child Unix program will exists. Mileage B<will> vary. (S<RISC OS>)
1437
e41182b5
GS
1438=item times
1439
1440Only the first entry returned is nonzero. (S<Mac OS>)
1441
1442"cumulative" times will be bogus. On anything other than Windows NT,
1443"system" time will be bogus, and "user" time is actually the time
1444returned by the clock() function in the C runtime library. (Win32)
1445
b8099c3d
CN
1446Not useful. (S<RISC OS>)
1447
e41182b5
GS
1448=item truncate FILEHANDLE,LENGTH
1449
1450=item truncate EXPR,LENGTH
1451
1452Not implemented. (VMS)
1453
495c5fdc
GP
1454Truncation to zero-length only. (VOS)
1455
4cfdb94f
GS
1456If a FILEHANDLE is supplied, it must be writable and opened in append
1457mode (i.e., use C<open(FH, '>>filename')>
1458or C<sysopen(FH,...,O_APPEND|O_RDWR)>. If a filename is supplied, it
1459should not be held open elsewhere. (Win32)
1460
e41182b5
GS
1461=item umask EXPR
1462
1463=item umask
1464
1465Returns undef where unavailable, as of version 5.005.
1466
1467=item utime LIST
1468
b8099c3d 1469Only the modification time is updated. (S<Mac OS>, VMS, S<RISC OS>)
e41182b5 1470
322422de
GS
1471May not behave as expected. Behavior depends on the C runtime
1472library's implementation of utime(), and the filesystem being
1473used. The FAT filesystem typically does not support an "access
1474time" field, and it may limit timestamps to a granularity of
1475two seconds. (Win32)
e41182b5
GS
1476
1477=item wait
1478
1479=item waitpid PID,FLAGS
1480
495c5fdc 1481Not implemented. (S<Mac OS>, VOS)
e41182b5
GS
1482
1483Can only be applied to process handles returned for processes spawned
1484using C<system(1, ...)>. (Win32)
1485
b8099c3d
CN
1486Not useful. (S<RISC OS>)
1487
e41182b5
GS
1488=back
1489
b8099c3d
CN
1490=head1 CHANGES
1491
1492=over 4
1493
495c5fdc
GP
1494=item 1.35, 9 September 1998
1495
1496Updated for Stratus VOS.
1497
0a47030a
GS
1498=item 1.33, 06 August 1998
1499
1500Integrate more minor changes.
1501
dd9f0070
CN
1502=item 1.32, 05 August 1998
1503
1504Integrate more minor changes.
1505
b8099c3d
CN
1506=item 1.30, 03 August 1998
1507
1508Major update for RISC OS, other minor changes.
1509
1510=item 1.23, 10 July 1998
1511
1512First public release with perl5.005.
1513
1514=back
e41182b5
GS
1515
1516=head1 AUTHORS / CONTRIBUTORS
1517
dd9f0070 1518Abigail E<lt>abigail@fnx.comE<gt>,
bd3fa61c 1519Charles Bailey E<lt>bailey@newman.upenn.eduE<gt>,
dd9f0070 1520Graham Barr E<lt>gbarr@pobox.comE<gt>,
e41182b5 1521Tom Christiansen E<lt>tchrist@perl.comE<gt>,
dd9f0070
CN
1522Nicholas Clark E<lt>Nicholas.Clark@liverpool.ac.ukE<gt>,
1523Andy Dougherty E<lt>doughera@lafcol.lafayette.eduE<gt>,
1524Dominic Dunlop E<lt>domo@vo.luE<gt>,
7c5ffed3 1525Neale Ferguson E<lt>neale@mailbox.tabnsw.com.auE<gt>
495c5fdc 1526Paul Green E<lt>Paul_Green@stratus.comE<gt>,
dd9f0070 1527M.J.T. Guy E<lt>mjtg@cus.cam.ac.ukE<gt>,
7c5ffed3 1528Jarkko Hietaniemi E<lt>jhi@iki.fi<gt>,
dd9f0070
CN
1529Luther Huffman E<lt>lutherh@stratcom.comE<gt>,
1530Nick Ing-Simmons E<lt>nick@ni-s.u-net.comE<gt>,
322422de 1531Andreas J. KE<ouml>nig E<lt>koenig@kulturbox.deE<gt>,
dd9f0070 1532Andrew M. Langmead E<lt>aml@world.std.comE<gt>,
e41182b5 1533Paul Moore E<lt>Paul.Moore@uk.origin-it.comE<gt>,
dd9f0070 1534Chris Nandor E<lt>pudge@pobox.comE<gt>,
322422de 1535Matthias Neeracher E<lt>neeri@iis.ee.ethz.chE<gt>,
e41182b5 1536Gary Ng E<lt>71564.1743@CompuServe.COME<gt>,
e41182b5 1537Tom Phoenix E<lt>rootbeer@teleport.comE<gt>,
dd9f0070 1538Peter Prymmer E<lt>pvhp@forte.comE<gt>,
322422de 1539Hugo van der Sanden E<lt>hv@crypt0.demon.co.ukE<gt>,
dd9f0070
CN
1540Gurusamy Sarathy E<lt>gsar@umich.eduE<gt>,
1541Paul J. Schinder E<lt>schinder@pobox.comE<gt>,
e41182b5 1542Dan Sugalski E<lt>sugalskd@ous.eduE<gt>,
dd9f0070 1543Nathan Torkington E<lt>gnat@frii.comE<gt>.
e41182b5
GS
1544
1545This document is maintained by Chris Nandor.
1546
1547=head1 VERSION
1548
495c5fdc
GP
1549Version 1.35, last modified 09 September 1998.
1550