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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
3c075c7d 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 platform),
232remember not to count on the existence or the contents of
233system-specific files or directories, like F</etc/passwd>,
234F</etc/sendmail.conf>, F</etc/resolv.conf>, or even F</tmp/>. For
235example, F</etc/passwd> may exist but it may not contain the encrypted
236passwords because the system is using some form of enhanced security --
237or it may not contain all the accounts because the system is using NIS.
238If code does need to rely on such a file, include a description of the
239file and its format in the code's documentation, and make it easy for
240the user to override the default location of the file.
241
242Don't assume a text file will end with a newline.
e41182b5 243
dd9f0070 244Do not have two files of the same name with different case, like
3c075c7d 245F<test.pl> and F<Test.pl>, as many platforms have case-insensitive
dd9f0070 246filenames. Also, try not to have non-word characters (except for C<.>)
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247in the names, and keep them to the 8.3 convention, for maximum
248portability.
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249
250Likewise, if using C<AutoSplit>, try to keep the split functions to
2518.3 naming and case-insensitive conventions; or, at the very least,
252make it so the resulting files have a unique (case-insensitively)
253first 8 characters.
254
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255Don't assume C<E<gt>> won't be the first character of a filename. Always
256use C<E<lt>> explicitly to open a file for reading.
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257
258 open(FILE, "<$existing_file") or die $!;
259
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260Actually, though, if filenames might use strange characters, it is
261safest to open it with C<sysopen> instead of C<open>, which is magic.
262
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263
264=head2 System Interaction
265
266Not all platforms provide for the notion of a command line, necessarily.
267These are usually platforms that rely on a Graphical User Interface (GUI)
268for user interaction. So a program requiring command lines might not work
269everywhere. But this is probably for the user of the program to deal
270with.
271
272Some platforms can't delete or rename files that are being held open by
273the system. Remember to C<close> files when you are done with them.
274Don't C<unlink> or C<rename> an open file. Don't C<tie> to or C<open> a
275file that is already tied to or opened; C<untie> or C<close> first.
276
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277Don't open the same file more than once at a time for writing, as some
278operating systems put mandatory locks on such files.
279
e41182b5 280Don't count on a specific environment variable existing in C<%ENV>.
0a47030a 281Don't count on C<%ENV> entries being case-sensitive, or even
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282case-preserving.
283
0a47030a 284Don't count on signals.
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285
286Don't count on filename globbing. Use C<opendir>, C<readdir>, and
287C<closedir> instead.
288
b8099c3d 289Don't count on per-program environment variables, or per-program current
dd9f0070 290directories.
b8099c3d 291
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292Don't count on specific values of C<$!>.
293
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294
295=head2 Interprocess Communication (IPC)
296
297In general, don't directly access the system in code that is meant to be
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298portable. That means, no C<system>, C<exec>, C<fork>, C<pipe>, C<``>,
299C<qx//>, C<open> with a C<|>, nor any of the other things that makes being
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300a Unix perl hacker worth being.
301
302Commands that launch external processes are generally supported on
303most platforms (though many of them do not support any type of forking),
304but the problem with using them arises from what you invoke with them.
305External tools are often named differently on different platforms, often
306not available in the same location, often accept different arguments,
307often behave differently, and often represent their results in a
308platform-dependent way. Thus you should seldom depend on them to produce
309consistent results.
310
311One especially common bit of Perl code is opening a pipe to sendmail:
312
313 open(MAIL, '|/usr/lib/sendmail -t') or die $!;
314
315This is fine for systems programming when sendmail is known to be
316available. But it is not fine for many non-Unix systems, and even
317some Unix systems that may not have sendmail installed. If a portable
318solution is needed, see the C<Mail::Send> and C<Mail::Mailer> modules
319in the C<MailTools> distribution. C<Mail::Mailer> provides several
320mailing methods, including mail, sendmail, and direct SMTP
321(via C<Net::SMTP>) if a mail transfer agent is not available.
322
323The rule of thumb for portable code is: Do it all in portable Perl, or
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324use a module (that may internally implement it with platform-specific
325code, but expose a common interface).
e41182b5 326
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327The UNIX System V IPC (C<msg*(), sem*(), shm*()>) is not available
328even in all UNIX platforms.
e41182b5 329
3c075c7d 330
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331=head2 External Subroutines (XS)
332
333XS code, in general, can be made to work with any platform; but dependent
334libraries, header files, etc., might not be readily available or
335portable, or the XS code itself might be platform-specific, just as Perl
336code might be. If the libraries and headers are portable, then it is
337normally reasonable to make sure the XS code is portable, too.
338
339There is a different kind of portability issue with writing XS
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340code: availability of a C compiler on the end-user's system. C brings
341with it its own portability issues, and writing XS code will expose you to
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342some of those. Writing purely in perl is a comparatively easier way to
343achieve portability.
344
345
346=head2 Standard Modules
347
348In general, the standard modules work across platforms. Notable
349exceptions are C<CPAN.pm> (which currently makes connections to external
350programs that may not be available), platform-specific modules (like
351C<ExtUtils::MM_VMS>), and DBM modules.
352
353There is no one DBM module that is available on all platforms.
354C<SDBM_File> and the others are generally available on all Unix and DOSish
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355ports, but not in MacPerl, where only C<NBDM_File> and C<DB_File> are
356available.
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357
358The good news is that at least some DBM module should be available, and
359C<AnyDBM_File> will use whichever module it can find. Of course, then
360the code needs to be fairly strict, dropping to the lowest common
361denominator (e.g., not exceeding 1K for each record).
362
363
364=head2 Time and Date
365
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366The system's notion of time of day and calendar date is controlled in
367widely different ways. Don't assume the timezone is stored in C<$ENV{TZ}>,
368and even if it is, don't assume that you can control the timezone through
369that variable.
e41182b5 370
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371Don't assume that the epoch starts at 00:00:00, January 1, 1970,
372because that is OS-specific. Better to store a date in an unambiguous
373representation. The ISO 8601 standard defines YYYY-MM-DD as the date
374format. A text representation (like C<1 Jan 1970>) can be easily
375converted into an OS-specific value using a module like
376C<Date::Parse>. An array of values, such as those returned by
377C<localtime>, can be converted to an OS-specific representation using
378C<Time::Local>.
379
380
381=head2 Character sets and character encoding
382
383Assume very little about character sets. Do not assume anything about
384the numerical values (C<ord()>, C<chr()>) of characters. Do not
385assume that the alphabetic characters are encoded contiguously (in
3c075c7d 386numerical sense). Do not assume anything about the ordering of the
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387characters. The lowercase letters may come before or after the
388uppercase letters, the lowercase and uppercase may be interlaced so
b1ff3570 389that both 'a' and 'A' come before the 'b', the accented and other
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390international characters may be interlaced so that E<auml> comes
391before the 'b'.
392
393
394=head2 Internationalisation
395
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396If you may assume POSIX (a rather large assumption, that in practice
397means UNIX), you may read more about the POSIX locale system from
322422de 398L<perllocale>. The locale system at least attempts to make things a
3c075c7d 399little bit more portable, or at least more convenient and
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400native-friendly for non-English users. The system affects character
401sets and encoding, and date and time formatting, among other things.
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402
403
404=head2 System Resources
405
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406If your code is destined for systems with severely constrained (or
407missing!) virtual memory systems then you want to be I<especially> mindful
408of avoiding wasteful constructs such as:
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409
410 # NOTE: this is no longer "bad" in perl5.005
411 for (0..10000000) {} # bad
412 for (my $x = 0; $x <= 10000000; ++$x) {} # good
413
414 @lines = <VERY_LARGE_FILE>; # bad
415
416 while (<FILE>) {$file .= $_} # sometimes bad
0a47030a 417 $file = join('', <FILE>); # better
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418
419The last two may appear unintuitive to most people. The first of those
420two constructs repeatedly grows a string, while the second allocates a
421large chunk of memory in one go. On some systems, the latter is more
422efficient that the former.
423
0a47030a 424
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425=head2 Security
426
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427Most multi-user platforms provide basic levels of security that is usually
428felt at the file-system level. Other platforms usually don't
429(unfortunately). Thus the notion of user id, or "home" directory, or even
430the state of being logged-in, may be unrecognizable on many platforms. If
431you write programs that are security conscious, it is usually best to know
432what type of system you will be operating under, and write code explicitly
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433for that platform (or class of platforms).
434
0a47030a 435
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436=head2 Style
437
438For those times when it is necessary to have platform-specific code,
439consider keeping the platform-specific code in one place, making porting
440to other platforms easier. Use the C<Config> module and the special
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441variable C<$^O> to differentiate platforms, as described in
442L<"PLATFORMS">.
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443
444
0a47030a 445=head1 CPAN Testers
e41182b5 446
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447Modules uploaded to CPAN are tested by a variety of volunteers on
448different platforms. These CPAN testers are notified by mail of each
e41182b5 449new upload, and reply to the list with PASS, FAIL, NA (not applicable to
0a47030a 450this platform), or UNKNOWN (unknown), along with any relevant notations.
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451
452The purpose of the testing is twofold: one, to help developers fix any
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453problems in their code that crop up because of lack of testing on other
454platforms; two, to provide users with information about whether or not
455a given module works on a given platform.
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456
457=over 4
458
459=item Mailing list: cpan-testers@perl.org
460
461=item Testing results: C<http://www.connect.net/gbarr/cpan-test/>
462
463=back
464
465
466=head1 PLATFORMS
467
468As of version 5.002, Perl is built with a C<$^O> variable that
469indicates the operating system it was built on. This was implemented
470to help speed up code that would otherwise have to C<use Config;> and
471use the value of C<$Config{'osname'}>. Of course, to get
472detailed information about the system, looking into C<%Config> is
473certainly recommended.
474
475=head2 Unix
476
477Perl works on a bewildering variety of Unix and Unix-like platforms (see
478e.g. most of the files in the F<hints/> directory in the source code kit).
479On most of these systems, the value of C<$^O> (hence C<$Config{'osname'}>,
480too) is determined by lowercasing and stripping punctuation from the first
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481field of the string returned by typing C<uname -a> (or a similar command)
482at the shell prompt. Here, for example, are a few of the more popular
483Unix flavors:
e41182b5 484
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485 uname $^O $Config{'archname'}
486 -------------------------------------------
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487 AIX aix aix
488 FreeBSD freebsd freebsd-i386
489 Linux linux i386-linux
490 HP-UX hpux PA-RISC1.1
3c075c7d 491 IRIX irix irix
322422de 492 OSF1 dec_osf alpha-dec_osf
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493 SunOS solaris sun4-solaris
494 SunOS solaris i86pc-solaris
322422de 495 SunOS4 sunos sun4-sunos
e41182b5 496
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497Note that because the C<$Config{'archname'}> may depend on the hardware
498architecture it may vary quite a lot, much more than the C<$^O>.
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499
500=head2 DOS and Derivatives
501
502Perl has long been ported to PC style microcomputers running under
503systems like PC-DOS, MS-DOS, OS/2, and most Windows platforms you can
504bring yourself to mention (except for Windows CE, if you count that).
505Users familiar with I<COMMAND.COM> and/or I<CMD.EXE> style shells should
506be aware that each of these file specifications may have subtle
507differences:
508
509 $filespec0 = "c:/foo/bar/file.txt";
510 $filespec1 = "c:\\foo\\bar\\file.txt";
511 $filespec2 = 'c:\foo\bar\file.txt';
512 $filespec3 = 'c:\\foo\\bar\\file.txt';
513
514System calls accept either C</> or C<\> as the path separator. However,
515many command-line utilities of DOS vintage treat C</> as the option
516prefix, so they may get confused by filenames containing C</>. Aside
517from calling any external programs, C</> will work just fine, and
518probably better, as it is more consistent with popular usage, and avoids
519the problem of remembering what to backwhack and what not to.
520
0a47030a 521The DOS FAT filesystem can only accommodate "8.3" style filenames. Under
e41182b5 522the "case insensitive, but case preserving" HPFS (OS/2) and NTFS (NT)
0a47030a 523filesystems you may have to be careful about case returned with functions
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524like C<readdir> or used with functions like C<open> or C<opendir>.
525
526DOS also treats several filenames as special, such as AUX, PRN, NUL, CON,
527COM1, LPT1, LPT2 etc. Unfortunately these filenames won't even work
528if you include an explicit directory prefix, in some cases. It is best
529to avoid such filenames, if you want your code to be portable to DOS
530and its derivatives.
531
532Users of these operating systems may also wish to make use of
533scripts such as I<pl2bat.bat> or I<pl2cmd> as appropriate to
534put wrappers around your scripts.
535
536Newline (C<\n>) is translated as C<\015\012> by STDIO when reading from
537and writing to files. C<binmode(FILEHANDLE)> will keep C<\n> translated
538as C<\012> for that filehandle. Since it is a noop on other systems,
539C<binmode> should be used for cross-platform code that deals with binary
540data.
541
542The C<$^O> variable and the C<$Config{'archname'}> values for various
543DOSish perls are as follows:
544
545 OS $^O $Config{'archname'}
546 --------------------------------------------
547 MS-DOS dos
548 PC-DOS dos
549 OS/2 os2
550 Windows 95 MSWin32 MSWin32-x86
551 Windows NT MSWin32 MSWin32-x86
552 Windows NT MSWin32 MSWin32-alpha
553 Windows NT MSWin32 MSWin32-ppc
554
555Also see:
556
557=over 4
558
559=item The djgpp environment for DOS, C<http://www.delorie.com/djgpp/>
560
561=item The EMX environment for DOS, OS/2, etc. C<emx@iaehv.nl>,
562C<http://www.juge.com/bbs/Hobb.19.html>
563
564=item Build instructions for Win32, L<perlwin32>.
565
566=item The ActiveState Pages, C<http://www.activestate.com/>
567
568=back
569
570
dd9f0070 571=head2 S<Mac OS>
e41182b5
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572
573Any module requiring XS compilation is right out for most people, because
574MacPerl is built using non-free (and non-cheap!) compilers. Some XS
575modules that can work with MacPerl are built and distributed in binary
0a47030a
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576form on CPAN. See I<MacPerl: Power and Ease> and L<"CPAN Testers">
577for more details.
e41182b5
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578
579Directories are specified as:
580
581 volume:folder:file for absolute pathnames
582 volume:folder: for absolute pathnames
583 :folder:file for relative pathnames
584 :folder: for relative pathnames
585 :file for relative pathnames
586 file for relative pathnames
587
588Files in a directory are stored in alphabetical order. Filenames are
589limited to 31 characters, and may include any character except C<:>,
590which is reserved as a path separator.
591
0a47030a 592Instead of C<flock>, see C<FSpSetFLock> and C<FSpRstFLock> in the
3c075c7d 593C<Mac::Files> module, or C<chmod(0444, ...)> and C<chmod(0666, ...)>.
e41182b5
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594
595In the MacPerl application, you can't run a program from the command line;
596programs that expect C<@ARGV> to be populated can be edited with something
597like the following, which brings up a dialog box asking for the command
598line arguments.
599
600 if (!@ARGV) {
601 @ARGV = split /\s+/, MacPerl::Ask('Arguments?');
602 }
603
604A MacPerl script saved as a droplet will populate C<@ARGV> with the full
605pathnames of the files dropped onto the script.
606
607Mac users can use programs on a kind of command line under MPW (Macintosh
608Programmer's Workshop, a free development environment from Apple).
609MacPerl was first introduced as an MPW tool, and MPW can be used like a
610shell:
611
612 perl myscript.plx some arguments
613
614ToolServer is another app from Apple that provides access to MPW tools
0a47030a 615from MPW and the MacPerl app, which allows MacPerl programs to use
e41182b5
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616C<system>, backticks, and piped C<open>.
617
618"S<Mac OS>" is the proper name for the operating system, but the value
619in C<$^O> is "MacOS". To determine architecture, version, or whether
620the application or MPW tool version is running, check:
621
622 $is_app = $MacPerl::Version =~ /App/;
623 $is_tool = $MacPerl::Version =~ /MPW/;
624 ($version) = $MacPerl::Version =~ /^(\S+)/;
625 $is_ppc = $MacPerl::Architecture eq 'MacPPC';
626 $is_68k = $MacPerl::Architecture eq 'Mac68K';
627
3c075c7d
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628S<Mac OS X>, to be based on NeXT's OpenStep OS, will (in theory) be able
629to run MacPerl natively, but Unix perl will also run natively under the
630built-in Unix environment.
e41182b5
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631
632Also see:
633
634=over 4
635
636=item The MacPerl Pages, C<http://www.ptf.com/macperl/>.
637
638=item The MacPerl mailing list, C<mac-perl-request@iis.ee.ethz.ch>.
639
640=back
641
642
643=head2 VMS
644
645Perl on VMS is discussed in F<vms/perlvms.pod> in the perl distribution.
0a47030a 646Note that perl on VMS can accept either VMS- or Unix-style file
e41182b5
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647specifications as in either of the following:
648
649 $ perl -ne "print if /perl_setup/i" SYS$LOGIN:LOGIN.COM
650 $ perl -ne "print if /perl_setup/i" /sys$login/login.com
651
652but not a mixture of both as in:
653
654 $ perl -ne "print if /perl_setup/i" sys$login:/login.com
655 Can't open sys$login:/login.com: file specification syntax error
656
657Interacting with Perl from the Digital Command Language (DCL) shell
658often requires a different set of quotation marks than Unix shells do.
659For example:
660
661 $ perl -e "print ""Hello, world.\n"""
662 Hello, world.
663
664There are a number of ways to wrap your perl scripts in DCL .COM files if
665you are so inclined. For example:
666
667 $ write sys$output "Hello from DCL!"
668 $ if p1 .eqs. ""
669 $ then perl -x 'f$environment("PROCEDURE")
670 $ else perl -x - 'p1 'p2 'p3 'p4 'p5 'p6 'p7 'p8
671 $ deck/dollars="__END__"
672 #!/usr/bin/perl
673
674 print "Hello from Perl!\n";
675
676 __END__
677 $ endif
678
679Do take care with C<$ ASSIGN/nolog/user SYS$COMMAND: SYS$INPUT> if your
680perl-in-DCL script expects to do things like C<$read = E<lt>STDINE<gt>;>.
681
682Filenames are in the format "name.extension;version". The maximum
683length for filenames is 39 characters, and the maximum length for
684extensions is also 39 characters. Version is a number from 1 to
68532767. Valid characters are C</[A-Z0-9$_-]/>.
686
687VMS' RMS filesystem is case insensitive and does not preserve case.
688C<readdir> returns lowercased filenames, but specifying a file for
b8099c3d 689opening remains case insensitive. Files without extensions have a
e41182b5 690trailing period on them, so doing a C<readdir> with a file named F<A.;5>
0a47030a
GS
691will return F<a.> (though that file could be opened with
692C<open(FH, 'A')>).
e41182b5 693
f34d0673 694RMS had an eight level limit on directory depths from any rooted logical
dd9f0070
CN
695(allowing 16 levels overall) prior to VMS 7.2. Hence
696C<PERL_ROOT:[LIB.2.3.4.5.6.7.8]> is a valid directory specification but
697C<PERL_ROOT:[LIB.2.3.4.5.6.7.8.9]> is not. F<Makefile.PL> authors might
698have to take this into account, but at least they can refer to the former
f34d0673 699as C</PERL_ROOT/lib/2/3/4/5/6/7/8/>.
e41182b5 700
0a47030a
GS
701The C<VMS::Filespec> module, which gets installed as part of the build
702process on VMS, is a pure Perl module that can easily be installed on
703non-VMS platforms and can be helpful for conversions to and from RMS
704native formats.
e41182b5
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705
706What C<\n> represents depends on the type of file that is open. It could
707be C<\015>, C<\012>, C<\015\012>, or nothing. Reading from a file
708translates newlines to C<\012>, unless C<binmode> was executed on that
709handle, just like DOSish perls.
710
711TCP/IP stacks are optional on VMS, so socket routines might not be
712implemented. UDP sockets may not be supported.
713
714The value of C<$^O> on OpenVMS is "VMS". To determine the architecture
715that you are running on without resorting to loading all of C<%Config>
716you can examine the content of the C<@INC> array like so:
717
718 if (grep(/VMS_AXP/, @INC)) {
719 print "I'm on Alpha!\n";
720 } elsif (grep(/VMS_VAX/, @INC)) {
721 print "I'm on VAX!\n";
722 } else {
723 print "I'm not so sure about where $^O is...\n";
724 }
725
726Also see:
727
728=over 4
729
730=item L<perlvms.pod>
731
732=item vmsperl list, C<vmsperl-request@newman.upenn.edu>
733
734Put words C<SUBSCRIBE VMSPERL> in message body.
735
736=item vmsperl on the web, C<http://www.sidhe.org/vmsperl/index.html>
737
738=back
739
740
495c5fdc
GP
741=head2 VOS
742
743Perl on VOS is discussed in F<README.vos> in the perl distribution.
744Note that perl on VOS can accept either VOS- or Unix-style file
745specifications as in either of the following:
746
747 $ perl -ne "print if /perl_setup/i" >system>notices
748 $ perl -ne "print if /perl_setup/i" /system/notices
749
750or even a mixture of both as in:
751
752 $ perl -ne "print if /perl_setup/i" >system/notices
753
754Note that even though VOS allows the slash character to appear in object
755names, because the VOS port of Perl interprets it as a pathname
756delimiting character, VOS files, directories, or links whose names
757contain a slash character cannot be processed. Such files must be
758renamed before they can be processed by Perl.
759
760The following C functions are unimplemented on VOS, any any attempt by
761Perl to use them will result in a fatal error message and an immediate
762exit from Perl: dup, do_aspawn, do_spawn, execlp, execl, execvp, fork,
763waitpid. Once these functions become available in the VOS POSIX.1
764implementation, you can either recompile and rebind Perl, or you can
765download a newer port from ftp.stratus.com.
766
767The value of C<$^O> on VOS is "VOS". To determine the architecture that
768you are running on without resorting to loading all of C<%Config> you
769can examine the content of the C<@INC> array like so:
770
771 if (grep(/VOS/, @INC)) {
772 print "I'm on a Stratus box!\n";
773 } else {
774 print "I'm not on a Stratus box!\n";
775 die;
776 }
777
778 if (grep(/860/, @INC)) {
779 print "This box is a Stratus XA/R!\n";
780 } elsif (grep(/7100/, @INC)) {
781 print "This box is a Stratus HP 7100 or 8000!\n";
782 } elsif (grep(/8000/, @INC)) {
783 print "This box is a Stratus HP 8000!\n";
784 } else {
785 print "This box is a Stratus 68K...\n";
786 }
787
788Also see:
789
790=over 4
791
792=item L<README.vos>
793
794=item VOS mailing list
795
796There is no specific mailing list for Perl on VOS. You can post
797comments to the comp.sys.stratus newsgroup, or subscribe to the general
798Stratus mailing list. Send a letter with "Subscribe Info-Stratus" in
799the message body to majordomo@list.stratagy.com.
800
801=item VOS Perl on the web at C<http://ftp.stratus.com/pub/vos/vos.html>
802
803=back
804
805
e41182b5
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806=head2 EBCDIC Platforms
807
808Recent versions of Perl have been ported to platforms such as OS/400 on
7c5ffed3
JH
809AS/400 minicomputers as well as OS/390 & VM/ESA for IBM Mainframes. Such
810computers use EBCDIC character sets internally (usually Character Code
811Set ID 00819 for OS/400 and IBM-1047 for OS/390 & VM/ESA). Note that on
812the mainframe perl currently works under the "Unix system services
813for OS/390" (formerly known as OpenEdition) and VM/ESA OpenEdition.
e41182b5 814
7c5ffed3
JH
815As of R2.5 of USS for OS/390 and Version 2.3 of VM/ESA these Unix
816sub-systems do not support the C<#!> shebang trick for script invocation.
817Hence, on OS/390 and VM/ESA perl scripts can be executed with a header
818similar to the following simple script:
e41182b5
GS
819
820 : # use perl
821 eval 'exec /usr/local/bin/perl -S $0 ${1+"$@"}'
822 if 0;
823 #!/usr/local/bin/perl # just a comment really
824
825 print "Hello from perl!\n";
826
827On these platforms, bear in mind that the EBCDIC character set may have
0a47030a
GS
828an effect on what happens with some perl functions (such as C<chr>,
829C<pack>, C<print>, C<printf>, C<ord>, C<sort>, C<sprintf>, C<unpack>), as
830well as bit-fiddling with ASCII constants using operators like C<^>, C<&>
831and C<|>, not to mention dealing with socket interfaces to ASCII computers
b687b08b 832(see L<Newlines>).
e41182b5
GS
833
834Fortunately, most web servers for the mainframe will correctly translate
835the C<\n> in the following statement to its ASCII equivalent (note that
7c5ffed3 836C<\r> is the same under both Unix and OS/390 & VM/ESA):
e41182b5
GS
837
838 print "Content-type: text/html\r\n\r\n";
839
840The value of C<$^O> on OS/390 is "os390".
841
7c5ffed3 842The value of C<$^O> on VM/ESA is "vmesa".
3c075c7d 843
e41182b5
GS
844Some simple tricks for determining if you are running on an EBCDIC
845platform could include any of the following (perhaps all):
846
847 if ("\t" eq "\05") { print "EBCDIC may be spoken here!\n"; }
848
849 if (ord('A') == 193) { print "EBCDIC may be spoken here!\n"; }
850
851 if (chr(169) eq 'z') { print "EBCDIC may be spoken here!\n"; }
852
853Note that one thing you may not want to rely on is the EBCDIC encoding
0a47030a
GS
854of punctuation characters since these may differ from code page to code
855page (and once your module or script is rumoured to work with EBCDIC,
856folks will want it to work with all EBCDIC character sets).
e41182b5
GS
857
858Also see:
859
860=over 4
861
862=item perl-mvs list
863
864The perl-mvs@perl.org list is for discussion of porting issues as well as
865general usage issues for all EBCDIC Perls. Send a message body of
866"subscribe perl-mvs" to majordomo@perl.org.
867
0a47030a 868=item AS/400 Perl information at C<http://as400.rochester.ibm.com/>
e41182b5
GS
869
870=back
871
b8099c3d
CN
872
873=head2 Acorn RISC OS
874
0a47030a
GS
875As Acorns use ASCII with newlines (C<\n>) in text files as C<\012> like
876Unix and Unix filename emulation is turned on by default, it is quite
877likely that most simple scripts will work "out of the box". The native
878filing system is modular, and individual filing systems are free to be
879case-sensitive or insensitive, and are usually case-preserving. Some
880native filing systems have name length limits which file and directory
881names are silently truncated to fit - scripts should be aware that the
882standard disc filing system currently has a name length limit of B<10>
883characters, with up to 77 items in a directory, but other filing systems
884may not impose such limitations.
b8099c3d
CN
885
886Native filenames are of the form
887
888 Filesystem#Special_Field::DiscName.$.Directory.Directory.File
dd9f0070 889
b8099c3d
CN
890where
891
892 Special_Field is not usually present, but may contain . and $ .
893 Filesystem =~ m|[A-Za-z0-9_]|
894 DsicName =~ m|[A-Za-z0-9_/]|
895 $ represents the root directory
896 . is the path separator
897 @ is the current directory (per filesystem but machine global)
898 ^ is the parent directory
899 Directory and File =~ m|[^\0- "\.\$\%\&:\@\\^\|\177]+|
900
901The default filename translation is roughly C<tr|/.|./|;>
902
903Note that C<"ADFS::HardDisc.$.File" ne 'ADFS::HardDisc.$.File'> and that
0a47030a
GS
904the second stage of C<$> interpolation in regular expressions will fall
905foul of the C<$.> if scripts are not careful.
906
907Logical paths specified by system variables containing comma-separated
908search lists are also allowed, hence C<System:Modules> is a valid
909filename, and the filesystem will prefix C<Modules> with each section of
910C<System$Path> until a name is made that points to an object on disc.
911Writing to a new file C<System:Modules> would only be allowed if
912C<System$Path> contains a single item list. The filesystem will also
913expand system variables in filenames if enclosed in angle brackets, so
914C<E<lt>System$DirE<gt>.Modules> would look for the file
915S<C<$ENV{'System$Dir'} . 'Modules'>>. The obvious implication of this is
3c075c7d 916that B<fully qualified filenames can start with C<E<lt>E<gt>>> and should
0a47030a 917be protected when C<open> is used for input.
b8099c3d
CN
918
919Because C<.> was in use as a directory separator and filenames could not
920be assumed to be unique after 10 characters, Acorn implemented the C
921compiler to strip the trailing C<.c> C<.h> C<.s> and C<.o> suffix from
922filenames specified in source code and store the respective files in
923subdirectories named after the suffix. Hence files are translated:
924
925 foo.h h.foo
926 C:foo.h C:h.foo (logical path variable)
927 sys/os.h sys.h.os (C compiler groks Unix-speak)
928 10charname.c c.10charname
929 10charname.o o.10charname
930 11charname_.c c.11charname (assuming filesystem truncates at 10)
931
932The Unix emulation library's translation of filenames to native assumes
0a47030a
GS
933that this sort of translation is required, and allows a user defined list
934of known suffixes which it will transpose in this fashion. This may
935appear transparent, but consider that with these rules C<foo/bar/baz.h>
936and C<foo/bar/h/baz> both map to C<foo.bar.h.baz>, and that C<readdir> and
937C<glob> cannot and do not attempt to emulate the reverse mapping. Other
938C<.>s in filenames are translated to C</>.
939
940As implied above the environment accessed through C<%ENV> is global, and
941the convention is that program specific environment variables are of the
942form C<Program$Name>. Each filing system maintains a current directory,
943and the current filing system's current directory is the B<global> current
944directory. Consequently, sociable scripts don't change the current
945directory but rely on full pathnames, and scripts (and Makefiles) cannot
946assume that they can spawn a child process which can change the current
947directory without affecting its parent (and everyone else for that
948matter).
949
950As native operating system filehandles are global and currently are
951allocated down from 255, with 0 being a reserved value the Unix emulation
952library emulates Unix filehandles. Consequently, you can't rely on
953passing C<STDIN>, C<STDOUT>, or C<STDERR> to your children.
954
955The desire of users to express filenames of the form
956C<E<lt>Foo$DirE<gt>.Bar> on the command line unquoted causes problems,
957too: C<``> command output capture has to perform a guessing game. It
958assumes that a string C<E<lt>[^E<lt>E<gt>]+\$[^E<lt>E<gt>]E<gt>> is a
959reference to an environment variable, whereas anything else involving
960C<E<lt>> or C<E<gt>> is redirection, and generally manages to be 99%
961right. Of course, the problem remains that scripts cannot rely on any
962Unix tools being available, or that any tools found have Unix-like command
963line arguments.
964
965Extensions and XS are, in theory, buildable by anyone using free tools.
966In practice, many don't, as users of the Acorn platform are used to binary
967distribution. MakeMaker does run, but no available make currently copes
968with MakeMaker's makefiles; even if/when this is fixed, the lack of a
969Unix-like shell can cause problems with makefile rules, especially lines
970of the form C<cd sdbm && make all>, and anything using quoting.
b8099c3d
CN
971
972"S<RISC OS>" is the proper name for the operating system, but the value
973in C<$^O> is "riscos" (because we don't like shouting).
974
975Also see:
976
977=over 4
978
979=item perl list
980
981=back
982
983
e41182b5
GS
984=head2 Other perls
985
b8099c3d
CN
986Perl has been ported to a variety of platforms that do not fit into any of
987the above categories. Some, such as AmigaOS, BeOS, QNX, and Plan 9, have
0a47030a 988been well-integrated into the standard Perl source code kit. You may need
b8099c3d 989to see the F<ports/> directory on CPAN for information, and possibly
0a47030a
GS
990binaries, for the likes of: aos, atari, lynxos, riscos, Tandem Guardian,
991vos, I<etc.> (yes we know that some of these OSes may fall under the Unix
992category, but we are not a standards body.)
e41182b5
GS
993
994See also:
995
996=over 4
997
998=item Atari, Guido Flohr's page C<http://stud.uni-sb.de/~gufl0000/>
999
1000=item HP 300 MPE/iX C<http://www.cccd.edu/~markb/perlix.html>
1001
1002=item Novell Netware
1003
0a47030a 1004A free perl5-based PERL.NLM for Novell Netware is available from
e41182b5
GS
1005C<http://www.novell.com/>
1006
1007=back
1008
1009
1010=head1 FUNCTION IMPLEMENTATIONS
1011
1012Listed below are functions unimplemented or implemented differently on
1013various platforms. Following each description will be, in parentheses, a
1014list of platforms that the description applies to.
1015
1016The list may very well be incomplete, or wrong in some places. When in
1017doubt, consult the platform-specific README files in the Perl source
1018distribution, and other documentation resources for a given port.
1019
0a47030a 1020Be aware, moreover, that even among Unix-ish systems there are variations.
e41182b5
GS
1021
1022For many functions, you can also query C<%Config>, exported by default
1023from C<Config.pm>. For example, to check if the platform has the C<lstat>
0a47030a
GS
1024call, check C<$Config{'d_lstat'}>. See L<Config.pm> for a full
1025description of available variables.
e41182b5
GS
1026
1027
1028=head2 Alphabetical Listing of Perl Functions
1029
1030=over 8
1031
1032=item -X FILEHANDLE
1033
1034=item -X EXPR
1035
1036=item -X
1037
1038C<-r>, C<-w>, and C<-x> have only a very limited meaning; directories
1039and applications are executable, and there are no uid/gid
1040considerations. C<-o> is not supported. (S<Mac OS>)
1041
1042C<-r>, C<-w>, C<-x>, and C<-o> tell whether or not file is accessible,
1043which may not reflect UIC-based file protections. (VMS)
1044
b8099c3d
CN
1045C<-s> returns the size of the data fork, not the total size of data fork
1046plus resource fork. (S<Mac OS>).
1047
1048C<-s> by name on an open file will return the space reserved on disk,
1049rather than the current extent. C<-s> on an open filehandle returns the
1050current size. (S<RISC OS>)
1051
e41182b5 1052C<-R>, C<-W>, C<-X>, C<-O> are indistinguishable from C<-r>, C<-w>,
b8099c3d 1053C<-x>, C<-o>. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5
GS
1054
1055C<-b>, C<-c>, C<-k>, C<-g>, C<-p>, C<-u>, C<-A> are not implemented.
1056(S<Mac OS>)
1057
1058C<-g>, C<-k>, C<-l>, C<-p>, C<-u>, C<-A> are not particularly meaningful.
b8099c3d 1059(Win32, VMS, S<RISC OS>)
e41182b5
GS
1060
1061C<-d> is true if passed a device spec without an explicit directory.
1062(VMS)
1063
1064C<-T> and C<-B> are implemented, but might misclassify Mac text files
0a47030a
GS
1065with foreign characters; this is the case will all platforms, but may
1066affect S<Mac OS> often. (S<Mac OS>)
e41182b5
GS
1067
1068C<-x> (or C<-X>) determine if a file ends in one of the executable
1069suffixes. C<-S> is meaningless. (Win32)
1070
b8099c3d
CN
1071C<-x> (or C<-X>) determine if a file has an executable file type.
1072(S<RISC OS>)
1073
e41182b5
GS
1074=item binmode FILEHANDLE
1075
b8099c3d 1076Meaningless. (S<Mac OS>, S<RISC OS>)
e41182b5
GS
1077
1078Reopens file and restores pointer; if function fails, underlying
1079filehandle may be closed, or pointer may be in a different position.
1080(VMS)
1081
1082The value returned by C<tell> may be affected after the call, and
1083the filehandle may be flushed. (Win32)
1084
1085=item chmod LIST
1086
1087Only limited meaning. Disabling/enabling write permission is mapped to
1088locking/unlocking the file. (S<Mac OS>)
1089
1090Only good for changing "owner" read-write access, "group", and "other"
1091bits are meaningless. (Win32)
1092
b8099c3d
CN
1093Only good for changing "owner" and "other" read-write access. (S<RISC OS>)
1094
495c5fdc
GP
1095Access permissions are mapped onto VOS access-control list changes. (VOS)
1096
e41182b5
GS
1097=item chown LIST
1098
495c5fdc 1099Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>, VOS)
e41182b5
GS
1100
1101Does nothing, but won't fail. (Win32)
1102
1103=item chroot FILENAME
1104
1105=item chroot
1106
7c5ffed3 1107Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>, VOS, VM/ESA)
e41182b5
GS
1108
1109=item crypt PLAINTEXT,SALT
1110
1111May not be available if library or source was not provided when building
b8099c3d 1112perl. (Win32)
e41182b5 1113
495c5fdc
GP
1114Not implemented. (VOS)
1115
e41182b5
GS
1116=item dbmclose HASH
1117
495c5fdc 1118Not implemented. (VMS, Plan9, VOS)
e41182b5
GS
1119
1120=item dbmopen HASH,DBNAME,MODE
1121
495c5fdc 1122Not implemented. (VMS, Plan9, VOS)
e41182b5
GS
1123
1124=item dump LABEL
1125
b8099c3d 1126Not useful. (S<Mac OS>, S<RISC OS>)
e41182b5
GS
1127
1128Not implemented. (Win32)
1129
b8099c3d 1130Invokes VMS debugger. (VMS)
e41182b5
GS
1131
1132=item exec LIST
1133
1134Not implemented. (S<Mac OS>)
1135
7c5ffed3 1136Implemented via Spawn. (VM/ESA)
3c075c7d 1137
e41182b5
GS
1138=item fcntl FILEHANDLE,FUNCTION,SCALAR
1139
1140Not implemented. (Win32, VMS)
1141
1142=item flock FILEHANDLE,OPERATION
1143
495c5fdc 1144Not implemented (S<Mac OS>, VMS, S<RISC OS>, VOS).
e41182b5
GS
1145
1146Available only on Windows NT (not on Windows 95). (Win32)
1147
1148=item fork
1149
7c5ffed3 1150Not implemented. (S<Mac OS>, Win32, AmigaOS, S<RISC OS>, VOS, VM/ESA)
e41182b5
GS
1151
1152=item getlogin
1153
b8099c3d 1154Not implemented. (S<Mac OS>, S<RISC OS>)
e41182b5
GS
1155
1156=item getpgrp PID
1157
495c5fdc 1158Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5
GS
1159
1160=item getppid
1161
b8099c3d 1162Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5
GS
1163
1164=item getpriority WHICH,WHO
1165
7c5ffed3 1166Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
e41182b5
GS
1167
1168=item getpwnam NAME
1169
1170Not implemented. (S<Mac OS>, Win32)
1171
b8099c3d
CN
1172Not useful. (S<RISC OS>)
1173
e41182b5
GS
1174=item getgrnam NAME
1175
b8099c3d 1176Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5
GS
1177
1178=item getnetbyname NAME
1179
1180Not implemented. (S<Mac OS>, Win32, Plan9)
1181
1182=item getpwuid UID
1183
1184Not implemented. (S<Mac OS>, Win32)
1185
b8099c3d
CN
1186Not useful. (S<RISC OS>)
1187
e41182b5
GS
1188=item getgrgid GID
1189
b8099c3d 1190Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5
GS
1191
1192=item getnetbyaddr ADDR,ADDRTYPE
1193
1194Not implemented. (S<Mac OS>, Win32, Plan9)
1195
1196=item getprotobynumber NUMBER
1197
1198Not implemented. (S<Mac OS>)
1199
1200=item getservbyport PORT,PROTO
1201
1202Not implemented. (S<Mac OS>)
1203
1204=item getpwent
1205
7c5ffed3 1206Not implemented. (S<Mac OS>, Win32, VM/ESA)
e41182b5
GS
1207
1208=item getgrent
1209
7c5ffed3 1210Not implemented. (S<Mac OS>, Win32, VMS, VM/ESA)
e41182b5
GS
1211
1212=item gethostent
1213
1214Not implemented. (S<Mac OS>, Win32)
1215
1216=item getnetent
1217
1218Not implemented. (S<Mac OS>, Win32, Plan9)
1219
1220=item getprotoent
1221
1222Not implemented. (S<Mac OS>, Win32, Plan9)
1223
1224=item getservent
1225
1226Not implemented. (Win32, Plan9)
1227
1228=item setpwent
1229
b8099c3d 1230Not implemented. (S<Mac OS>, Win32, S<RISC OS>)
e41182b5
GS
1231
1232=item setgrent
1233
b8099c3d 1234Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5
GS
1235
1236=item sethostent STAYOPEN
1237
b8099c3d 1238Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>)
e41182b5
GS
1239
1240=item setnetent STAYOPEN
1241
b8099c3d 1242Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>)
e41182b5
GS
1243
1244=item setprotoent STAYOPEN
1245
b8099c3d 1246Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>)
e41182b5
GS
1247
1248=item setservent STAYOPEN
1249
b8099c3d 1250Not implemented. (Plan9, Win32, S<RISC OS>)
e41182b5
GS
1251
1252=item endpwent
1253
7c5ffed3 1254Not implemented. (S<Mac OS>, Win32, VM/ESA)
e41182b5
GS
1255
1256=item endgrent
1257
7c5ffed3 1258Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VM/ESA)
e41182b5
GS
1259
1260=item endhostent
1261
1262Not implemented. (S<Mac OS>, Win32)
1263
1264=item endnetent
1265
1266Not implemented. (S<Mac OS>, Win32, Plan9)
1267
1268=item endprotoent
1269
1270Not implemented. (S<Mac OS>, Win32, Plan9)
1271
1272=item endservent
1273
1274Not implemented. (Plan9, Win32)
1275
1276=item getsockopt SOCKET,LEVEL,OPTNAME
1277
1278Not implemented. (S<Mac OS>, Plan9)
1279
1280=item glob EXPR
1281
1282=item glob
1283
1284Globbing built-in, but only C<*> and C<?> metacharacters are supported.
1285(S<Mac OS>)
1286
0a47030a
GS
1287Features depend on external perlglob.exe or perlglob.bat. May be
1288overridden with something like File::DosGlob, which is recommended.
1289(Win32)
e41182b5 1290
b8099c3d 1291Globbing built-in, but only C<*> and C<?> metacharacters are supported.
0a47030a
GS
1292Globbing relies on operating system calls, which may return filenames
1293in any order. As most filesystems are case-insensitive, even "sorted"
1294filenames will not be in case-sensitive order. (S<RISC OS>)
b8099c3d 1295
e41182b5
GS
1296=item ioctl FILEHANDLE,FUNCTION,SCALAR
1297
1298Not implemented. (VMS)
1299
1300Available only for socket handles, and it does what the ioctlsocket() call
1301in the Winsock API does. (Win32)
1302
b8099c3d
CN
1303Available only for socket handles. (S<RISC OS>)
1304
e41182b5
GS
1305=item kill LIST
1306
0a47030a
GS
1307Not implemented, hence not useful for taint checking. (S<Mac OS>,
1308S<RISC OS>)
e41182b5 1309
0a47030a
GS
1310Available only for process handles returned by the C<system(1, ...)>
1311method of spawning a process. (Win32)
e41182b5
GS
1312
1313=item link OLDFILE,NEWFILE
1314
b8099c3d 1315Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5
GS
1316
1317=item lstat FILEHANDLE
1318
1319=item lstat EXPR
1320
1321=item lstat
1322
b8099c3d 1323Not implemented. (VMS, S<RISC OS>)
e41182b5 1324
b8099c3d 1325Return values may be bogus. (Win32)
e41182b5
GS
1326
1327=item msgctl ID,CMD,ARG
1328
1329=item msgget KEY,FLAGS
1330
1331=item msgsnd ID,MSG,FLAGS
1332
1333=item msgrcv ID,VAR,SIZE,TYPE,FLAGS
1334
495c5fdc 1335Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>, VOS)
e41182b5
GS
1336
1337=item open FILEHANDLE,EXPR
1338
1339=item open FILEHANDLE
1340
1341The C<|> variants are only supported if ToolServer is installed.
1342(S<Mac OS>)
1343
b8099c3d 1344open to C<|-> and C<-|> are unsupported. (S<Mac OS>, Win32, S<RISC OS>)
e41182b5
GS
1345
1346=item pipe READHANDLE,WRITEHANDLE
1347
1348Not implemented. (S<Mac OS>)
1349
1350=item readlink EXPR
1351
1352=item readlink
1353
b8099c3d 1354Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5
GS
1355
1356=item select RBITS,WBITS,EBITS,TIMEOUT
1357
1358Only implemented on sockets. (Win32)
1359
b8099c3d
CN
1360Only reliable on sockets. (S<RISC OS>)
1361
e41182b5
GS
1362=item semctl ID,SEMNUM,CMD,ARG
1363
1364=item semget KEY,NSEMS,FLAGS
1365
1366=item semop KEY,OPSTRING
1367
495c5fdc 1368Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5
GS
1369
1370=item setpgrp PID,PGRP
1371
495c5fdc 1372Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5
GS
1373
1374=item setpriority WHICH,WHO,PRIORITY
1375
495c5fdc 1376Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5
GS
1377
1378=item setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL
1379
1380Not implemented. (S<Mac OS>, Plan9)
1381
1382=item shmctl ID,CMD,ARG
1383
1384=item shmget KEY,SIZE,FLAGS
1385
1386=item shmread ID,VAR,POS,SIZE
1387
1388=item shmwrite ID,STRING,POS,SIZE
1389
495c5fdc 1390Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5
GS
1391
1392=item socketpair SOCKET1,SOCKET2,DOMAIN,TYPE,PROTOCOL
1393
7c5ffed3 1394Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
e41182b5
GS
1395
1396=item stat FILEHANDLE
1397
1398=item stat EXPR
1399
1400=item stat
1401
1402mtime and atime are the same thing, and ctime is creation time instead of
1403inode change time. (S<Mac OS>)
1404
1405device and inode are not meaningful. (Win32)
1406
1407device and inode are not necessarily reliable. (VMS)
1408
b8099c3d
CN
1409mtime, atime and ctime all return the last modification time. Device and
1410inode are not necessarily reliable. (S<RISC OS>)
1411
e41182b5
GS
1412=item symlink OLDFILE,NEWFILE
1413
b8099c3d 1414Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5
GS
1415
1416=item syscall LIST
1417
7c5ffed3 1418Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
e41182b5 1419
f34d0673
GS
1420=item sysopen FILEHANDLE,FILENAME,MODE,PERMS
1421
dd9f0070 1422The traditional "0", "1", and "2" MODEs are implemented with different
322422de
GS
1423numeric values on some systems. The flags exported by C<Fcntl>
1424(O_RDONLY, O_WRONLY, O_RDWR) should work everywhere though. (S<Mac
7c5ffed3 1425OS>, OS/390, VM/ESA)
f34d0673 1426
e41182b5
GS
1427=item system LIST
1428
1429Only implemented if ToolServer is installed. (S<Mac OS>)
1430
1431As an optimization, may not call the command shell specified in
1432C<$ENV{PERL5SHELL}>. C<system(1, @args)> spawns an external
1433process and immediately returns its process designator, without
1434waiting for it to terminate. Return value may be used subsequently
1435in C<wait> or C<waitpid>. (Win32)
1436
b8099c3d
CN
1437There is no shell to process metacharacters, and the native standard is
1438to pass a command line terminated by "\n" "\r" or "\0" to the spawned
1439program. Redirection such as C<E<gt> foo> is performed (if at all) by
1440the run time library of the spawned program. C<system> I<list> will call
1441the Unix emulation library's C<exec> emulation, which attempts to provide
1442emulation of the stdin, stdout, stderr in force in the parent, providing
1443the child program uses a compatible version of the emulation library.
1444I<scalar> will call the native command line direct and no such emulation
1445of a child Unix program will exists. Mileage B<will> vary. (S<RISC OS>)
1446
e41182b5
GS
1447=item times
1448
1449Only the first entry returned is nonzero. (S<Mac OS>)
1450
1451"cumulative" times will be bogus. On anything other than Windows NT,
1452"system" time will be bogus, and "user" time is actually the time
1453returned by the clock() function in the C runtime library. (Win32)
1454
b8099c3d
CN
1455Not useful. (S<RISC OS>)
1456
e41182b5
GS
1457=item truncate FILEHANDLE,LENGTH
1458
1459=item truncate EXPR,LENGTH
1460
1461Not implemented. (VMS)
1462
495c5fdc
GP
1463Truncation to zero-length only. (VOS)
1464
4cfdb94f
GS
1465If a FILEHANDLE is supplied, it must be writable and opened in append
1466mode (i.e., use C<open(FH, '>>filename')>
1467or C<sysopen(FH,...,O_APPEND|O_RDWR)>. If a filename is supplied, it
1468should not be held open elsewhere. (Win32)
1469
e41182b5
GS
1470=item umask EXPR
1471
1472=item umask
1473
1474Returns undef where unavailable, as of version 5.005.
1475
1476=item utime LIST
1477
b8099c3d 1478Only the modification time is updated. (S<Mac OS>, VMS, S<RISC OS>)
e41182b5 1479
322422de
GS
1480May not behave as expected. Behavior depends on the C runtime
1481library's implementation of utime(), and the filesystem being
1482used. The FAT filesystem typically does not support an "access
1483time" field, and it may limit timestamps to a granularity of
1484two seconds. (Win32)
e41182b5
GS
1485
1486=item wait
1487
1488=item waitpid PID,FLAGS
1489
495c5fdc 1490Not implemented. (S<Mac OS>, VOS)
e41182b5
GS
1491
1492Can only be applied to process handles returned for processes spawned
1493using C<system(1, ...)>. (Win32)
1494
b8099c3d
CN
1495Not useful. (S<RISC OS>)
1496
e41182b5
GS
1497=back
1498
b8099c3d
CN
1499=head1 CHANGES
1500
1501=over 4
1502
3c075c7d
CN
1503=item v1.37, 19 December 1998
1504
1505More minor changes. Merge two separate version 1.35 documents.
1506
1507=item v1.36, 9 September 1998
1508
1509Updated for Stratus VOS. Also known as version 1.35.
1510
1511=item v1.35, 13 August 1998
495c5fdc 1512
3c075c7d
CN
1513Integrate more minor changes, plus addition of new sections under
1514L<"ISSUES">: L<"Numbers endianness and Width">,
1515L<"Character sets and character encoding">,
1516L<"Internationalisation">.
495c5fdc 1517
3c075c7d 1518=item v1.33, 06 August 1998
0a47030a
GS
1519
1520Integrate more minor changes.
1521
3c075c7d 1522=item v1.32, 05 August 1998
dd9f0070
CN
1523
1524Integrate more minor changes.
1525
3c075c7d 1526=item v1.30, 03 August 1998
b8099c3d
CN
1527
1528Major update for RISC OS, other minor changes.
1529
3c075c7d 1530=item v1.23, 10 July 1998
b8099c3d
CN
1531
1532First public release with perl5.005.
1533
1534=back
e41182b5
GS
1535
1536=head1 AUTHORS / CONTRIBUTORS
1537
dd9f0070 1538Abigail E<lt>abigail@fnx.comE<gt>,
bd3fa61c 1539Charles Bailey E<lt>bailey@newman.upenn.eduE<gt>,
dd9f0070 1540Graham Barr E<lt>gbarr@pobox.comE<gt>,
e41182b5 1541Tom Christiansen E<lt>tchrist@perl.comE<gt>,
dd9f0070
CN
1542Nicholas Clark E<lt>Nicholas.Clark@liverpool.ac.ukE<gt>,
1543Andy Dougherty E<lt>doughera@lafcol.lafayette.eduE<gt>,
1544Dominic Dunlop E<lt>domo@vo.luE<gt>,
7c5ffed3 1545Neale Ferguson E<lt>neale@mailbox.tabnsw.com.auE<gt>
495c5fdc 1546Paul Green E<lt>Paul_Green@stratus.comE<gt>,
dd9f0070 1547M.J.T. Guy E<lt>mjtg@cus.cam.ac.ukE<gt>,
7c5ffed3 1548Jarkko Hietaniemi E<lt>jhi@iki.fi<gt>,
dd9f0070
CN
1549Luther Huffman E<lt>lutherh@stratcom.comE<gt>,
1550Nick Ing-Simmons E<lt>nick@ni-s.u-net.comE<gt>,
322422de 1551Andreas J. KE<ouml>nig E<lt>koenig@kulturbox.deE<gt>,
3c075c7d 1552Markus Laker E<lt>mlaker@contax.co.ukE<gt>,
dd9f0070 1553Andrew M. Langmead E<lt>aml@world.std.comE<gt>,
e41182b5 1554Paul Moore E<lt>Paul.Moore@uk.origin-it.comE<gt>,
dd9f0070 1555Chris Nandor E<lt>pudge@pobox.comE<gt>,
322422de 1556Matthias Neeracher E<lt>neeri@iis.ee.ethz.chE<gt>,
e41182b5 1557Gary Ng E<lt>71564.1743@CompuServe.COME<gt>,
e41182b5 1558Tom Phoenix E<lt>rootbeer@teleport.comE<gt>,
dd9f0070 1559Peter Prymmer E<lt>pvhp@forte.comE<gt>,
322422de 1560Hugo van der Sanden E<lt>hv@crypt0.demon.co.ukE<gt>,
dd9f0070
CN
1561Gurusamy Sarathy E<lt>gsar@umich.eduE<gt>,
1562Paul J. Schinder E<lt>schinder@pobox.comE<gt>,
e41182b5 1563Dan Sugalski E<lt>sugalskd@ous.eduE<gt>,
dd9f0070 1564Nathan Torkington E<lt>gnat@frii.comE<gt>.
e41182b5 1565
3c075c7d
CN
1566This document is maintained by Chris Nandor
1567E<lt>pudge@pobox.comE<gt>.
e41182b5
GS
1568
1569=head1 VERSION
1570
3c075c7d 1571Version 1.37, last modified 19 December 1998
495c5fdc 1572