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1 | =head1 NAME |
2 | |
3 | perlport - Writing portable Perl |
4 | |
5 | |
6 | =head1 DESCRIPTION |
7 | |
8 | Perl runs on a variety of operating systems. While most of them share |
9 | a lot in common, they also have their own very particular and unique |
10 | features. |
11 | |
12 | This document is meant to help you to find out what constitutes portable |
13 | perl code, so that once you have made your decision to write portably, |
14 | you know where the lines are drawn, and you can stay within them. |
15 | |
16 | There is a tradeoff between taking full advantage of B<a> particular type |
17 | of computer, and taking advantage of a full B<range> of them. Naturally, |
18 | as you make your range bigger (and thus more diverse), the common denominators |
19 | drop, and you are left with fewer areas of common ground in which |
20 | you can operate to accomplish a particular task. Thus, when you begin |
21 | attacking a problem, it is important to consider which part of the tradeoff |
22 | curve you want to operate under. Specifically, whether it is important to |
23 | you that the task that you are coding needs the full generality of being |
24 | portable, or if it is sufficient to just get the job done. This is the |
25 | hardest choice to be made. The rest is easy, because Perl provides lots |
26 | of choices, whichever way you want to approach your problem. |
27 | |
28 | Looking at it another way, writing portable code is usually about willfully |
29 | limiting your available choices. Naturally, it takes discipline to do that. |
30 | |
31 | Be aware of two important points: |
32 | |
33 | =over 4 |
34 | |
35 | =item Not all Perl programs have to be portable |
36 | |
37 | There is no reason why you should not use Perl as a language to glue Unix |
38 | tools together, or to prototype a Macintosh application, or to manage the |
39 | Windows registry. If it makes no sense to aim for portability for one |
40 | reason or another in a given program, then don't bother. |
41 | |
42 | =item The vast majority of Perl B<is> portable |
43 | |
44 | Don't be fooled into thinking that it is hard to create portable Perl |
45 | code. It isn't. Perl tries its level-best to bridge the gaps between |
46 | what's available on different platforms, and all the means available to |
47 | use those features. Thus almost all Perl code runs on any machine |
48 | without modification. But there I<are> some significant issues in |
49 | writing portable code, and this document is entirely about those issues. |
50 | |
51 | =back |
52 | |
53 | Here's the general rule: When you approach a task that is commonly done |
54 | using a whole range of platforms, think in terms of writing portable |
55 | code. That way, you don't sacrifice much by way of the implementation |
56 | choices you can avail yourself of, and at the same time you can give |
57 | your users lots of platform choices. On the other hand, when you have to |
58 | take advantage of some unique feature of a particular platform, as is |
59 | often the case with systems programming (whether for Unix, Windows, |
60 | S<Mac OS>, VMS, etc.), consider writing platform-specific code. |
61 | |
62 | When the code will run on only two or three operating systems, then you may |
63 | only need to consider the differences of those particular systems. The |
64 | important thing is to decide where the code will run, and to be deliberate |
65 | in your decision. |
66 | |
67 | This information should not be considered complete; it includes possibly |
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68 | transient information about idiosyncrasies of some of the ports, almost |
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69 | all of which are in a state of constant evolution. Thus this material |
70 | should be considered a perpetual work in progress |
71 | (E<lt>IMG SRC="yellow_sign.gif" ALT="Under Construction"E<gt>). |
72 | |
73 | |
74 | =head1 ISSUES |
75 | |
76 | =head2 Newlines |
77 | |
78 | In most operating systems, lines in files are separated with newlines. |
79 | Just what is used as a newline may vary from OS to OS. Unix |
80 | traditionally uses C<\012>, one kind of Windows I/O uses C<\015\012>, |
81 | and S<Mac OS> uses C<\015>. |
82 | |
83 | Perl uses C<\n> to represent the "logical" newline, where what |
84 | is logical may depend on the platform in use. In MacPerl, C<\n> |
85 | always means C<\015>. In DOSish perls, C<\n> usually means C<\012>, but |
86 | when accessing a file in "text" mode, STDIO translates it to (or from) |
87 | C<\015\012>. |
88 | |
89 | Due to the "text" mode translation, DOSish perls have limitations |
90 | of using C<seek> and C<tell> when a file is being accessed in "text" |
91 | mode. Specifically, if you stick to C<seek>-ing to locations you got |
92 | from C<tell> (and no others), you are usually free to use C<seek> and |
93 | C<tell> even in "text" mode. In general, using C<seek> or C<tell> or |
94 | other file operations that count bytes instead of characters, without |
95 | considering the length of C<\n>, may be non-portable. If you use |
96 | C<binmode> on a file, however, you can usually use C<seek> and C<tell> |
97 | with arbitrary values quite safely. |
98 | |
99 | A common misconception in socket programming is that C<\n> eq C<\012> |
100 | everywhere. When using protocols, such as common Internet protocols, |
101 | C<\012> and C<\015> are called for specifically, and the values of |
102 | the logical C<\n> and C<\r> (carriage return) are not reliable. |
103 | |
104 | print SOCKET "Hi there, client!\r\n"; # WRONG |
105 | print SOCKET "Hi there, client!\015\012"; # RIGHT |
106 | |
107 | [NOTE: this does not necessarily apply to communications that are |
108 | filtered by another program or module before sending to the socket; the |
109 | the most popular EBCDIC webserver, for instance, accepts C<\r\n>, |
110 | which translates those characters, along with all other |
111 | characters in text streams, from EBCDIC to ASCII.] |
112 | |
113 | However, C<\015\012> (or C<\cM\cJ>, or C<\x0D\x0A>) can be tedious and |
114 | unsightly, as well as confusing to those maintaining the code. As such, |
115 | the C<Socket> module supplies the Right Thing for those who want it. |
116 | |
117 | use Socket qw(:DEFAULT :crlf); |
118 | print SOCKET "Hi there, client!$CRLF" # RIGHT |
119 | |
120 | When reading I<from> a socket, remember that the default input record |
121 | separator (C<$/>) is C<\n>, but code like this should recognize C<$/> as |
122 | C<\012> or C<\015\012>: |
123 | |
124 | while (<SOCKET>) { |
125 | # ... |
126 | } |
127 | |
128 | Better: |
129 | |
130 | use Socket qw(:DEFAULT :crlf); |
131 | local($/) = LF; # not needed if $/ is already \012 |
132 | |
133 | while (<SOCKET>) { |
134 | s/$CR?$LF/\n/; # not sure if socket uses LF or CRLF, OK |
135 | # s/\015?\012/\n/; # same thing |
136 | } |
137 | |
138 | And this example is actually better than the previous one even for Unix |
139 | platforms, because now any C<\015>'s (C<\cM>'s) are stripped out |
140 | (and there was much rejoicing). |
141 | |
142 | |
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143 | =head2 Files |
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144 | |
145 | Most platforms these days structure files in a hierarchical fashion. |
146 | So, it is reasonably safe to assume that any platform supports the |
147 | notion of a "path" to uniquely identify a file on the system. Just |
148 | how that path is actually written, differs. |
149 | |
150 | While they are similar, file path specifications differ between Unix, |
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151 | Windows, S<Mac OS>, OS/2, VMS, S<RISC OS> and probably others. Unix, |
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152 | for example, is one of the few OSes that has the idea of a root directory. |
153 | S<Mac OS> uses C<:> as a path separator instead of C</>. VMS, Windows, and |
154 | OS/2 can work similarly to Unix with C</> as path separator, or in their own |
155 | idiosyncratic ways. C<RISC OS> perl can emulate Unix filenames with C</> |
156 | as path separator, or go native and use C<.> for path separator and C<:> |
157 | to signal filing systems and disc names. |
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158 | |
159 | As with the newline problem above, there are modules that can help. The |
160 | C<File::Spec> modules provide methods to do the Right Thing on whatever |
161 | platform happens to be running the program. |
162 | |
163 | use File::Spec; |
164 | chdir(File::Spec->updir()); # go up one directory |
165 | $file = File::Spec->catfile( |
166 | File::Spec->curdir(), 'temp', 'file.txt' |
167 | ); |
168 | # on Unix and Win32, './temp/file.txt' |
169 | # on Mac OS, ':temp:file.txt' |
170 | |
171 | File::Spec is available in the standard distribution, as of version |
172 | 5.004_05. |
173 | |
174 | In general, production code should not have file paths hardcoded; making |
175 | them user supplied or from a configuration file is better, keeping in mind |
176 | that file path syntax varies on different machines. |
177 | |
178 | This is especially noticeable in scripts like Makefiles and test suites, |
179 | which often assume C</> as a path separator for subdirectories. |
180 | |
181 | Also of use is C<File::Basename>, from the standard distribution, which |
182 | splits a pathname into pieces (base filename, full path to directory, |
183 | and file suffix). |
184 | |
185 | Remember not to count on the existence of system-specific files, like |
186 | F</etc/resolv.conf>. If code does need to rely on such a file, include a |
187 | description of the file and its format in the code's documentation, and |
188 | make it easy for the user to override the default location of the file. |
189 | |
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190 | Don't assume that a you can open a full pathname for input with |
191 | C<open (FILE, $name)>, as some platforms can use characters such as C<E<lt>> |
192 | which will perl C<open> will interpret and eat. |
193 | |
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194 | Do not have two files of the same name with different case, like |
195 | F<test.pl> and <Test.pl>, as many platforms have case-insensitive |
196 | filenames. Also, try not to have non-word characters (except for C<.>) |
197 | in the names, and keep them to the 8.3 convention, for maximum portability. |
198 | |
199 | Likewise, if using C<AutoSplit>, try to keep the split functions to |
200 | 8.3 naming and case-insensitive conventions; or, at the very least, |
201 | make it so the resulting files have a unique (case-insensitively) |
202 | first 8 characters. |
203 | |
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204 | |
205 | =head2 System Interaction |
206 | |
207 | Not all platforms provide for the notion of a command line, necessarily. |
208 | These are usually platforms that rely on a Graphical User Interface (GUI) |
209 | for user interaction. So a program requiring command lines might not work |
210 | everywhere. But this is probably for the user of the program to deal |
211 | with. |
212 | |
213 | Some platforms can't delete or rename files that are being held open by |
214 | the system. Remember to C<close> files when you are done with them. |
215 | Don't C<unlink> or C<rename> an open file. Don't C<tie> to or C<open> a |
216 | file that is already tied to or opened; C<untie> or C<close> first. |
217 | |
218 | Don't count on a specific environment variable existing in C<%ENV>. |
219 | Don't even count on C<%ENV> entries being case-sensitive, or even |
220 | case-preserving. |
221 | |
222 | Don't count on signals in portable programs. |
223 | |
224 | Don't count on filename globbing. Use C<opendir>, C<readdir>, and |
225 | C<closedir> instead. |
226 | |
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227 | Don't count on per-program environment variables, or per-program current |
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228 | directories. |
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229 | |
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230 | |
231 | =head2 Interprocess Communication (IPC) |
232 | |
233 | In general, don't directly access the system in code that is meant to be |
234 | portable. That means, no: C<system>, C<exec>, C<fork>, C<pipe>, C<``>, |
235 | C<qx//>, C<open> with a C<|>, or any of the other things that makes being |
236 | a Unix perl hacker worth being. |
237 | |
238 | Commands that launch external processes are generally supported on |
239 | most platforms (though many of them do not support any type of forking), |
240 | but the problem with using them arises from what you invoke with them. |
241 | External tools are often named differently on different platforms, often |
242 | not available in the same location, often accept different arguments, |
243 | often behave differently, and often represent their results in a |
244 | platform-dependent way. Thus you should seldom depend on them to produce |
245 | consistent results. |
246 | |
247 | One especially common bit of Perl code is opening a pipe to sendmail: |
248 | |
249 | open(MAIL, '|/usr/lib/sendmail -t') or die $!; |
250 | |
251 | This is fine for systems programming when sendmail is known to be |
252 | available. But it is not fine for many non-Unix systems, and even |
253 | some Unix systems that may not have sendmail installed. If a portable |
254 | solution is needed, see the C<Mail::Send> and C<Mail::Mailer> modules |
255 | in the C<MailTools> distribution. C<Mail::Mailer> provides several |
256 | mailing methods, including mail, sendmail, and direct SMTP |
257 | (via C<Net::SMTP>) if a mail transfer agent is not available. |
258 | |
259 | The rule of thumb for portable code is: Do it all in portable Perl, or |
260 | use a module that may internally implement it with platform-specific code, |
261 | but expose a common interface. By portable Perl, we mean code that |
262 | avoids the constructs described in this document as being non-portable. |
263 | |
264 | |
265 | =head2 External Subroutines (XS) |
266 | |
267 | XS code, in general, can be made to work with any platform; but dependent |
268 | libraries, header files, etc., might not be readily available or |
269 | portable, or the XS code itself might be platform-specific, just as Perl |
270 | code might be. If the libraries and headers are portable, then it is |
271 | normally reasonable to make sure the XS code is portable, too. |
272 | |
273 | There is a different kind of portability issue with writing XS |
274 | code: availability of a C compiler on the end-user's system. C brings with |
275 | it its own portability issues, and writing XS code will expose you to |
276 | some of those. Writing purely in perl is a comparatively easier way to |
277 | achieve portability. |
278 | |
279 | |
280 | =head2 Standard Modules |
281 | |
282 | In general, the standard modules work across platforms. Notable |
283 | exceptions are C<CPAN.pm> (which currently makes connections to external |
284 | programs that may not be available), platform-specific modules (like |
285 | C<ExtUtils::MM_VMS>), and DBM modules. |
286 | |
287 | There is no one DBM module that is available on all platforms. |
288 | C<SDBM_File> and the others are generally available on all Unix and DOSish |
289 | ports, but not in MacPerl, where C<NBDM_File> and C<DB_File> are available. |
290 | |
291 | The good news is that at least some DBM module should be available, and |
292 | C<AnyDBM_File> will use whichever module it can find. Of course, then |
293 | the code needs to be fairly strict, dropping to the lowest common |
294 | denominator (e.g., not exceeding 1K for each record). |
295 | |
296 | |
297 | =head2 Time and Date |
298 | |
299 | The system's notion of time of day and calendar date is controlled in widely |
300 | different ways. Don't assume the timezone is stored in C<$ENV{TZ}>, and even |
301 | if it is, don't assume that you can control the timezone through that |
302 | variable. |
303 | |
304 | Don't assume that the epoch starts at January 1, 1970, because that is |
305 | OS-specific. Better to store a date in an unambiguous representation. |
306 | A text representation (like C<1 Jan 1970>) can be easily converted into an |
307 | OS-specific value using a module like C<Date::Parse>. An array of values, |
308 | such as those returned by C<localtime>, can be converted to an OS-specific |
309 | representation using C<Time::Local>. |
310 | |
311 | |
312 | =head2 System Resources |
313 | |
314 | If your code is destined for systems with severely constrained (or missing!) |
315 | virtual memory systems then you want to be especially mindful of avoiding |
316 | wasteful constructs such as: |
317 | |
318 | # NOTE: this is no longer "bad" in perl5.005 |
319 | for (0..10000000) {} # bad |
320 | for (my $x = 0; $x <= 10000000; ++$x) {} # good |
321 | |
322 | @lines = <VERY_LARGE_FILE>; # bad |
323 | |
324 | while (<FILE>) {$file .= $_} # sometimes bad |
325 | $file = join '', <FILE>; # better |
326 | |
327 | The last two may appear unintuitive to most people. The first of those |
328 | two constructs repeatedly grows a string, while the second allocates a |
329 | large chunk of memory in one go. On some systems, the latter is more |
330 | efficient that the former. |
331 | |
332 | =head2 Security |
333 | |
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334 | Most multi-user platforms provide basic levels of security that is usually felt |
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335 | at the file-system level. Other platforms usually don't (unfortunately). |
336 | Thus the notion of User-ID, or "home" directory, or even the state of |
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337 | being logged-in may be unrecognizable on many platforms. If you write |
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338 | programs that are security conscious, it is usually best to know what |
339 | type of system you will be operating under, and write code explicitly |
340 | for that platform (or class of platforms). |
341 | |
342 | =head2 Style |
343 | |
344 | For those times when it is necessary to have platform-specific code, |
345 | consider keeping the platform-specific code in one place, making porting |
346 | to other platforms easier. Use the C<Config> module and the special |
347 | variable C<$^O> to differentiate platforms, as described in L<"PLATFORMS">. |
348 | |
349 | |
350 | =head1 CPAN TESTERS |
351 | |
352 | Module uploaded to CPAN are tested by a variety of volunteers on |
353 | different platforms. These CPAN testers are notified by e-mail of each |
354 | new upload, and reply to the list with PASS, FAIL, NA (not applicable to |
355 | this platform), or ???? (unknown), along with any relevant notations. |
356 | |
357 | The purpose of the testing is twofold: one, to help developers fix any |
358 | problems in their code; two, to provide users with information about |
359 | whether or not a given module works on a given platform. |
360 | |
361 | =over 4 |
362 | |
363 | =item Mailing list: cpan-testers@perl.org |
364 | |
365 | =item Testing results: C<http://www.connect.net/gbarr/cpan-test/> |
366 | |
367 | =back |
368 | |
369 | |
370 | =head1 PLATFORMS |
371 | |
372 | As of version 5.002, Perl is built with a C<$^O> variable that |
373 | indicates the operating system it was built on. This was implemented |
374 | to help speed up code that would otherwise have to C<use Config;> and |
375 | use the value of C<$Config{'osname'}>. Of course, to get |
376 | detailed information about the system, looking into C<%Config> is |
377 | certainly recommended. |
378 | |
379 | =head2 Unix |
380 | |
381 | Perl works on a bewildering variety of Unix and Unix-like platforms (see |
382 | e.g. most of the files in the F<hints/> directory in the source code kit). |
383 | On most of these systems, the value of C<$^O> (hence C<$Config{'osname'}>, |
384 | too) is determined by lowercasing and stripping punctuation from the first |
385 | field of the string returned by typing |
386 | |
387 | % uname -a |
388 | |
389 | (or a similar command) at the shell prompt. Here, for example, are a few |
390 | of the more popular Unix flavors: |
391 | |
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392 | uname $^O $Config{'archname'} |
393 | ------------------------------------------- |
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394 | AIX aix |
395 | FreeBSD freebsd |
396 | Linux linux |
397 | HP-UX hpux |
398 | OSF1 dec_osf |
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399 | SunOS solaris sun4-solaris |
400 | SunOS solaris i86pc-solaris |
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401 | SunOS4 sunos |
402 | |
403 | |
404 | =head2 DOS and Derivatives |
405 | |
406 | Perl has long been ported to PC style microcomputers running under |
407 | systems like PC-DOS, MS-DOS, OS/2, and most Windows platforms you can |
408 | bring yourself to mention (except for Windows CE, if you count that). |
409 | Users familiar with I<COMMAND.COM> and/or I<CMD.EXE> style shells should |
410 | be aware that each of these file specifications may have subtle |
411 | differences: |
412 | |
413 | $filespec0 = "c:/foo/bar/file.txt"; |
414 | $filespec1 = "c:\\foo\\bar\\file.txt"; |
415 | $filespec2 = 'c:\foo\bar\file.txt'; |
416 | $filespec3 = 'c:\\foo\\bar\\file.txt'; |
417 | |
418 | System calls accept either C</> or C<\> as the path separator. However, |
419 | many command-line utilities of DOS vintage treat C</> as the option |
420 | prefix, so they may get confused by filenames containing C</>. Aside |
421 | from calling any external programs, C</> will work just fine, and |
422 | probably better, as it is more consistent with popular usage, and avoids |
423 | the problem of remembering what to backwhack and what not to. |
424 | |
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425 | The DOS FAT file system can only accommodate "8.3" style filenames. Under |
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426 | the "case insensitive, but case preserving" HPFS (OS/2) and NTFS (NT) |
427 | file systems you may have to be careful about case returned with functions |
428 | like C<readdir> or used with functions like C<open> or C<opendir>. |
429 | |
430 | DOS also treats several filenames as special, such as AUX, PRN, NUL, CON, |
431 | COM1, LPT1, LPT2 etc. Unfortunately these filenames won't even work |
432 | if you include an explicit directory prefix, in some cases. It is best |
433 | to avoid such filenames, if you want your code to be portable to DOS |
434 | and its derivatives. |
435 | |
436 | Users of these operating systems may also wish to make use of |
437 | scripts such as I<pl2bat.bat> or I<pl2cmd> as appropriate to |
438 | put wrappers around your scripts. |
439 | |
440 | Newline (C<\n>) is translated as C<\015\012> by STDIO when reading from |
441 | and writing to files. C<binmode(FILEHANDLE)> will keep C<\n> translated |
442 | as C<\012> for that filehandle. Since it is a noop on other systems, |
443 | C<binmode> should be used for cross-platform code that deals with binary |
444 | data. |
445 | |
446 | The C<$^O> variable and the C<$Config{'archname'}> values for various |
447 | DOSish perls are as follows: |
448 | |
449 | OS $^O $Config{'archname'} |
450 | -------------------------------------------- |
451 | MS-DOS dos |
452 | PC-DOS dos |
453 | OS/2 os2 |
454 | Windows 95 MSWin32 MSWin32-x86 |
455 | Windows NT MSWin32 MSWin32-x86 |
456 | Windows NT MSWin32 MSWin32-alpha |
457 | Windows NT MSWin32 MSWin32-ppc |
458 | |
459 | Also see: |
460 | |
461 | =over 4 |
462 | |
463 | =item The djgpp environment for DOS, C<http://www.delorie.com/djgpp/> |
464 | |
465 | =item The EMX environment for DOS, OS/2, etc. C<emx@iaehv.nl>, |
466 | C<http://www.juge.com/bbs/Hobb.19.html> |
467 | |
468 | =item Build instructions for Win32, L<perlwin32>. |
469 | |
470 | =item The ActiveState Pages, C<http://www.activestate.com/> |
471 | |
472 | =back |
473 | |
474 | |
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475 | =head2 S<Mac OS> |
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476 | |
477 | Any module requiring XS compilation is right out for most people, because |
478 | MacPerl is built using non-free (and non-cheap!) compilers. Some XS |
479 | modules that can work with MacPerl are built and distributed in binary |
480 | form on CPAN. See I<MacPerl: Power and Ease> for more details. |
481 | |
482 | Directories are specified as: |
483 | |
484 | volume:folder:file for absolute pathnames |
485 | volume:folder: for absolute pathnames |
486 | :folder:file for relative pathnames |
487 | :folder: for relative pathnames |
488 | :file for relative pathnames |
489 | file for relative pathnames |
490 | |
491 | Files in a directory are stored in alphabetical order. Filenames are |
492 | limited to 31 characters, and may include any character except C<:>, |
493 | which is reserved as a path separator. |
494 | |
495 | Instead of C<flock>, see C<FSpSetFLock> and C<FSpRstFLock> in |
496 | C<Mac::Files>. |
497 | |
498 | In the MacPerl application, you can't run a program from the command line; |
499 | programs that expect C<@ARGV> to be populated can be edited with something |
500 | like the following, which brings up a dialog box asking for the command |
501 | line arguments. |
502 | |
503 | if (!@ARGV) { |
504 | @ARGV = split /\s+/, MacPerl::Ask('Arguments?'); |
505 | } |
506 | |
507 | A MacPerl script saved as a droplet will populate C<@ARGV> with the full |
508 | pathnames of the files dropped onto the script. |
509 | |
510 | Mac users can use programs on a kind of command line under MPW (Macintosh |
511 | Programmer's Workshop, a free development environment from Apple). |
512 | MacPerl was first introduced as an MPW tool, and MPW can be used like a |
513 | shell: |
514 | |
515 | perl myscript.plx some arguments |
516 | |
517 | ToolServer is another app from Apple that provides access to MPW tools |
518 | from MPW and the MacPerl app, which allows MacPerl program to use |
519 | C<system>, backticks, and piped C<open>. |
520 | |
521 | "S<Mac OS>" is the proper name for the operating system, but the value |
522 | in C<$^O> is "MacOS". To determine architecture, version, or whether |
523 | the application or MPW tool version is running, check: |
524 | |
525 | $is_app = $MacPerl::Version =~ /App/; |
526 | $is_tool = $MacPerl::Version =~ /MPW/; |
527 | ($version) = $MacPerl::Version =~ /^(\S+)/; |
528 | $is_ppc = $MacPerl::Architecture eq 'MacPPC'; |
529 | $is_68k = $MacPerl::Architecture eq 'Mac68K'; |
530 | |
dd9f0070 |
531 | S<Mac OS X>, to be based on NeXT's OpenStep OS, will be able to run MacPerl |
532 | natively (in the Blue Box, and even in the Yellow Box, once some changes |
533 | to the toolbox calls are made), but Unix perl will also run natively. |
e41182b5 |
534 | |
535 | Also see: |
536 | |
537 | =over 4 |
538 | |
539 | =item The MacPerl Pages, C<http://www.ptf.com/macperl/>. |
540 | |
541 | =item The MacPerl mailing list, C<mac-perl-request@iis.ee.ethz.ch>. |
542 | |
543 | =back |
544 | |
545 | |
546 | =head2 VMS |
547 | |
548 | Perl on VMS is discussed in F<vms/perlvms.pod> in the perl distribution. |
549 | Note that perl on VMS can accept either VMS or Unix style file |
550 | specifications as in either of the following: |
551 | |
552 | $ perl -ne "print if /perl_setup/i" SYS$LOGIN:LOGIN.COM |
553 | $ perl -ne "print if /perl_setup/i" /sys$login/login.com |
554 | |
555 | but not a mixture of both as in: |
556 | |
557 | $ perl -ne "print if /perl_setup/i" sys$login:/login.com |
558 | Can't open sys$login:/login.com: file specification syntax error |
559 | |
560 | Interacting with Perl from the Digital Command Language (DCL) shell |
561 | often requires a different set of quotation marks than Unix shells do. |
562 | For example: |
563 | |
564 | $ perl -e "print ""Hello, world.\n""" |
565 | Hello, world. |
566 | |
567 | There are a number of ways to wrap your perl scripts in DCL .COM files if |
568 | you are so inclined. For example: |
569 | |
570 | $ write sys$output "Hello from DCL!" |
571 | $ if p1 .eqs. "" |
572 | $ then perl -x 'f$environment("PROCEDURE") |
573 | $ else perl -x - 'p1 'p2 'p3 'p4 'p5 'p6 'p7 'p8 |
574 | $ deck/dollars="__END__" |
575 | #!/usr/bin/perl |
576 | |
577 | print "Hello from Perl!\n"; |
578 | |
579 | __END__ |
580 | $ endif |
581 | |
582 | Do take care with C<$ ASSIGN/nolog/user SYS$COMMAND: SYS$INPUT> if your |
583 | perl-in-DCL script expects to do things like C<$read = E<lt>STDINE<gt>;>. |
584 | |
585 | Filenames are in the format "name.extension;version". The maximum |
586 | length for filenames is 39 characters, and the maximum length for |
587 | extensions is also 39 characters. Version is a number from 1 to |
588 | 32767. Valid characters are C</[A-Z0-9$_-]/>. |
589 | |
590 | VMS' RMS filesystem is case insensitive and does not preserve case. |
591 | C<readdir> returns lowercased filenames, but specifying a file for |
b8099c3d |
592 | opening remains case insensitive. Files without extensions have a |
e41182b5 |
593 | trailing period on them, so doing a C<readdir> with a file named F<A.;5> |
594 | will return F<a.> (though that file could be opened with C<open(FH, 'A')>. |
595 | |
f34d0673 |
596 | RMS had an eight level limit on directory depths from any rooted logical |
dd9f0070 |
597 | (allowing 16 levels overall) prior to VMS 7.2. Hence |
598 | C<PERL_ROOT:[LIB.2.3.4.5.6.7.8]> is a valid directory specification but |
599 | C<PERL_ROOT:[LIB.2.3.4.5.6.7.8.9]> is not. F<Makefile.PL> authors might |
600 | have to take this into account, but at least they can refer to the former |
f34d0673 |
601 | as C</PERL_ROOT/lib/2/3/4/5/6/7/8/>. |
e41182b5 |
602 | |
603 | The C<VMS::Filespec> module, which gets installed as part |
604 | of the build process on VMS, is a pure Perl module that can easily be |
605 | installed on non-VMS platforms and can be helpful for conversions to |
606 | and from RMS native formats. |
607 | |
608 | What C<\n> represents depends on the type of file that is open. It could |
609 | be C<\015>, C<\012>, C<\015\012>, or nothing. Reading from a file |
610 | translates newlines to C<\012>, unless C<binmode> was executed on that |
611 | handle, just like DOSish perls. |
612 | |
613 | TCP/IP stacks are optional on VMS, so socket routines might not be |
614 | implemented. UDP sockets may not be supported. |
615 | |
616 | The value of C<$^O> on OpenVMS is "VMS". To determine the architecture |
617 | that you are running on without resorting to loading all of C<%Config> |
618 | you can examine the content of the C<@INC> array like so: |
619 | |
620 | if (grep(/VMS_AXP/, @INC)) { |
621 | print "I'm on Alpha!\n"; |
622 | } elsif (grep(/VMS_VAX/, @INC)) { |
623 | print "I'm on VAX!\n"; |
624 | } else { |
625 | print "I'm not so sure about where $^O is...\n"; |
626 | } |
627 | |
628 | Also see: |
629 | |
630 | =over 4 |
631 | |
632 | =item L<perlvms.pod> |
633 | |
634 | =item vmsperl list, C<vmsperl-request@newman.upenn.edu> |
635 | |
636 | Put words C<SUBSCRIBE VMSPERL> in message body. |
637 | |
638 | =item vmsperl on the web, C<http://www.sidhe.org/vmsperl/index.html> |
639 | |
640 | =back |
641 | |
642 | |
643 | =head2 EBCDIC Platforms |
644 | |
645 | Recent versions of Perl have been ported to platforms such as OS/400 on |
646 | AS/400 minicomputers as well as OS/390 for IBM Mainframes. Such computers |
647 | use EBCDIC character sets internally (usually Character Code Set ID 00819 |
648 | for OS/400 and IBM-1047 for OS/390). Note that on the mainframe perl |
649 | currently works under the "Unix system services for OS/390" (formerly |
650 | known as OpenEdition). |
651 | |
652 | As of R2.5 of USS for OS/390 that Unix sub-system did not support the |
653 | C<#!> shebang trick for script invocation. Hence, on OS/390 perl scripts |
654 | can executed with a header similar to the following simple script: |
655 | |
656 | : # use perl |
657 | eval 'exec /usr/local/bin/perl -S $0 ${1+"$@"}' |
658 | if 0; |
659 | #!/usr/local/bin/perl # just a comment really |
660 | |
661 | print "Hello from perl!\n"; |
662 | |
663 | On these platforms, bear in mind that the EBCDIC character set may have |
664 | an effect on what happens with perl functions such as C<chr>, C<pack>, |
665 | C<print>, C<printf>, C<ord>, C<sort>, C<sprintf>, C<unpack>; as well as |
666 | bit-fiddling with ASCII constants using operators like C<^>, C<&> and |
667 | C<|>; not to mention dealing with socket interfaces to ASCII computers |
668 | (see L<"NEWLINES">). |
669 | |
670 | Fortunately, most web servers for the mainframe will correctly translate |
671 | the C<\n> in the following statement to its ASCII equivalent (note that |
672 | C<\r> is the same under both ASCII and EBCDIC): |
673 | |
674 | print "Content-type: text/html\r\n\r\n"; |
675 | |
676 | The value of C<$^O> on OS/390 is "os390". |
677 | |
678 | Some simple tricks for determining if you are running on an EBCDIC |
679 | platform could include any of the following (perhaps all): |
680 | |
681 | if ("\t" eq "\05") { print "EBCDIC may be spoken here!\n"; } |
682 | |
683 | if (ord('A') == 193) { print "EBCDIC may be spoken here!\n"; } |
684 | |
685 | if (chr(169) eq 'z') { print "EBCDIC may be spoken here!\n"; } |
686 | |
687 | Note that one thing you may not want to rely on is the EBCDIC encoding |
688 | of punctuation characters since these may differ from code page to code page |
689 | (and once your module or script is rumoured to work with EBCDIC, folks will |
690 | want it to work with all EBCDIC character sets). |
691 | |
692 | Also see: |
693 | |
694 | =over 4 |
695 | |
696 | =item perl-mvs list |
697 | |
698 | The perl-mvs@perl.org list is for discussion of porting issues as well as |
699 | general usage issues for all EBCDIC Perls. Send a message body of |
700 | "subscribe perl-mvs" to majordomo@perl.org. |
701 | |
702 | =item AS/400 Perl information at C<http://as400.rochester.ibm.com> |
703 | |
704 | =back |
705 | |
b8099c3d |
706 | |
707 | =head2 Acorn RISC OS |
708 | |
709 | As Acorns use ASCII with newlines (C<\n>) in text files as C<\012> like Unix |
710 | and Unix filename emulation is turned on by default, it is quite likely that |
711 | most simple scripts will work "out of the box". The native filing system is |
712 | modular, and individual filing systems are free to be case sensitive or |
713 | insensitive, usually case preserving. Some native filing systems have name |
714 | length limits which file and directory names are silently truncated to fit - |
715 | scripts should be aware that the standard disc filing system currently has |
716 | a name length limit of B<10> characters, with up to 77 items in a directory, |
717 | but other filing systems may not impose such limitations. |
718 | |
719 | Native filenames are of the form |
720 | |
721 | Filesystem#Special_Field::DiscName.$.Directory.Directory.File |
dd9f0070 |
722 | |
b8099c3d |
723 | where |
724 | |
725 | Special_Field is not usually present, but may contain . and $ . |
726 | Filesystem =~ m|[A-Za-z0-9_]| |
727 | DsicName =~ m|[A-Za-z0-9_/]| |
728 | $ represents the root directory |
729 | . is the path separator |
730 | @ is the current directory (per filesystem but machine global) |
731 | ^ is the parent directory |
732 | Directory and File =~ m|[^\0- "\.\$\%\&:\@\\^\|\177]+| |
733 | |
734 | The default filename translation is roughly C<tr|/.|./|;> |
735 | |
736 | Note that C<"ADFS::HardDisc.$.File" ne 'ADFS::HardDisc.$.File'> and that |
737 | the second stage of $ interpolation in regular expressions will fall foul |
738 | of the C<$.> if scripts are not careful. |
739 | |
740 | Logical paths specified by system variables containing comma separated |
741 | search lists are also allowed, hence C<System:Modules> is a valid filename, |
742 | and the filesystem will prefix C<Modules> with each section of C<System$Path> |
743 | until a name is made that points to an object on disc. Writing to a new |
744 | file C<System:Modules> would only be allowed if C<System$Path> contains a |
745 | single item list. The filesystem will also expand system variables in |
746 | filenames if enclosed in angle brackets, so C<E<lt>System$DirE<gt>.Modules> |
747 | would look for the file S<C<$ENV{'System$Dir'} . 'Modules'>>. The obvious |
748 | implication of this is that B<fully qualified filenames can start with C<E<lt>E<gt>>> |
749 | and should be protected when C<open> is used for input. |
750 | |
751 | Because C<.> was in use as a directory separator and filenames could not |
752 | be assumed to be unique after 10 characters, Acorn implemented the C |
753 | compiler to strip the trailing C<.c> C<.h> C<.s> and C<.o> suffix from |
754 | filenames specified in source code and store the respective files in |
755 | subdirectories named after the suffix. Hence files are translated: |
756 | |
757 | foo.h h.foo |
758 | C:foo.h C:h.foo (logical path variable) |
759 | sys/os.h sys.h.os (C compiler groks Unix-speak) |
760 | 10charname.c c.10charname |
761 | 10charname.o o.10charname |
762 | 11charname_.c c.11charname (assuming filesystem truncates at 10) |
763 | |
764 | The Unix emulation library's translation of filenames to native assumes |
765 | that this sort of translation is required, and allows a user defined list of |
766 | known suffixes which it will transpose in this fashion. This may appear |
767 | transparent, but consider that with these rules C<foo/bar/baz.h> and |
768 | C<foo/bar/h/baz> both map to C<foo.bar.h.baz>, and that C<readdir> and |
769 | C<glob> cannot and do not attempt to emulate the reverse mapping. Other '.'s |
770 | in filenames are translated to '/'. |
771 | |
772 | S<RISC OS> has "image files", files that behave as directories. For |
773 | example with suitable software this allows the contents of a zip file to |
774 | be treated as a directory at command line (and therefore script) level, |
775 | with full read-write random access. At present the perl port treats images |
776 | as directories: C<-d> returns true, C<-f> false, and C<unlink> checks to |
777 | ensure that recognised images are empty before deleting them. In theory |
778 | images should never trouble a script, but in practice they may do so if |
779 | the software to deal with an image file is loaded and registered while the |
780 | script is running, as suddenly "files" that it had cached information on |
781 | metamorphose into directories. |
782 | |
783 | As implied above the environment accessed through C<%ENV> is global, and the |
784 | convention is that program specific environment variables are of the form |
785 | C<Program$Name>. Each filing system maintains a current directory, and |
786 | the current filing system's current directory is the B<global> current |
787 | directory. Consequently sociable scripts don't change the current directory |
788 | but rely on full pathnames, and scripts (and Makefiles) cannot assume that |
789 | they can spawn a child process which can change the current directory |
790 | without affecting its parent (and everyone else for that matter). |
791 | |
792 | As native operating system filehandles are global and currently are allocated |
793 | down from 255, with 0 being a reserved value the Unix emulation library |
794 | emulates Unix filehandles. Consequently you can't rely on passing C<STDIN> |
795 | C<STDOUT> or C<STDERR> to your children. Run time libraries perform |
796 | command line processing to emulate Unix shell style C<>> redirection, but |
797 | the core operating system is written in assembler and has its own private, |
798 | obscure and somewhat broken convention. All this is further complicated by |
799 | the desire of users to express filenames of the form C<E<lt>Foo$DirE<gt>.Bar> on |
800 | the command line unquoted. (Oh yes, it's run time libraries interpreting the |
801 | quoting convention.) Hence C<``> command output capture has to perform |
dd9f0070 |
802 | a guessing game as to how the command is going to interpret the command line |
803 | so that it can bodge it correctly to capture output. It assumes that a |
b8099c3d |
804 | string C<E<lt>[^E<lt>E<gt>]+\$[^E<lt>E<gt>]E<gt>> is a reference to an environment |
805 | variable, whereas anything else involving C<E<lt>> or C<E<gt>> is redirection, |
806 | and generally manages to be 99% right. Despite all this the problem remains |
807 | that scripts cannot rely on any Unix tools being available, or that any tools |
808 | found have Unix-like command line arguments. |
809 | |
810 | Extensions and XS are in theory buildable by anyone using free tools. In |
811 | practice many don't as the Acorn platform is used to binary distribution. |
812 | MakeMaker does itself run, but no make currently copes with MakeMaker's |
813 | makefiles! Even if (when) this is fixed os that the lack of a Unix-like |
814 | shell can cause problems with makefile rules, especially lines of the form |
815 | C<cd sdbm && make all> and anything using quoting. |
816 | |
817 | "S<RISC OS>" is the proper name for the operating system, but the value |
818 | in C<$^O> is "riscos" (because we don't like shouting). |
819 | |
820 | Also see: |
821 | |
822 | =over 4 |
823 | |
824 | =item perl list |
825 | |
826 | =back |
827 | |
828 | |
e41182b5 |
829 | =head2 Other perls |
830 | |
b8099c3d |
831 | Perl has been ported to a variety of platforms that do not fit into any of |
832 | the above categories. Some, such as AmigaOS, BeOS, QNX, and Plan 9, have |
833 | been well integrated into the standard Perl source code kit. You may need |
834 | to see the F<ports/> directory on CPAN for information, and possibly |
dd9f0070 |
835 | binaries, for the likes of: aos, atari, lynxos, HP-MPE/iX, riscos, |
b8099c3d |
836 | Tandem Guardian, vos, I<etc.> (yes we know that some of these OSes may fall |
837 | under the Unix category but we are not a standards body.) |
e41182b5 |
838 | |
839 | See also: |
840 | |
841 | =over 4 |
842 | |
843 | =item Atari, Guido Flohr's page C<http://stud.uni-sb.de/~gufl0000/> |
844 | |
845 | =item HP 300 MPE/iX C<http://www.cccd.edu/~markb/perlix.html> |
846 | |
847 | =item Novell Netware |
848 | |
849 | A free Perl 5 based PERL.NLM for Novell Netware is available from |
850 | C<http://www.novell.com/> |
851 | |
852 | =back |
853 | |
854 | |
855 | =head1 FUNCTION IMPLEMENTATIONS |
856 | |
857 | Listed below are functions unimplemented or implemented differently on |
858 | various platforms. Following each description will be, in parentheses, a |
859 | list of platforms that the description applies to. |
860 | |
861 | The list may very well be incomplete, or wrong in some places. When in |
862 | doubt, consult the platform-specific README files in the Perl source |
863 | distribution, and other documentation resources for a given port. |
864 | |
865 | Be aware, moreover, that even among Unix-ish systems there are variations, |
866 | and not all functions listed here are necessarily available, though |
867 | most usually are. |
868 | |
869 | For many functions, you can also query C<%Config>, exported by default |
870 | from C<Config.pm>. For example, to check if the platform has the C<lstat> |
871 | call, check C<$Config{'d_lstat'}>. See L<Config> for a full description |
872 | of available variables. |
873 | |
874 | |
875 | =head2 Alphabetical Listing of Perl Functions |
876 | |
877 | =over 8 |
878 | |
879 | =item -X FILEHANDLE |
880 | |
881 | =item -X EXPR |
882 | |
883 | =item -X |
884 | |
885 | C<-r>, C<-w>, and C<-x> have only a very limited meaning; directories |
886 | and applications are executable, and there are no uid/gid |
887 | considerations. C<-o> is not supported. (S<Mac OS>) |
888 | |
889 | C<-r>, C<-w>, C<-x>, and C<-o> tell whether or not file is accessible, |
890 | which may not reflect UIC-based file protections. (VMS) |
891 | |
b8099c3d |
892 | C<-s> returns the size of the data fork, not the total size of data fork |
893 | plus resource fork. (S<Mac OS>). |
894 | |
895 | C<-s> by name on an open file will return the space reserved on disk, |
896 | rather than the current extent. C<-s> on an open filehandle returns the |
897 | current size. (S<RISC OS>) |
898 | |
e41182b5 |
899 | C<-R>, C<-W>, C<-X>, C<-O> are indistinguishable from C<-r>, C<-w>, |
b8099c3d |
900 | C<-x>, C<-o>. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
901 | |
902 | C<-b>, C<-c>, C<-k>, C<-g>, C<-p>, C<-u>, C<-A> are not implemented. |
903 | (S<Mac OS>) |
904 | |
905 | C<-g>, C<-k>, C<-l>, C<-p>, C<-u>, C<-A> are not particularly meaningful. |
b8099c3d |
906 | (Win32, VMS, S<RISC OS>) |
e41182b5 |
907 | |
908 | C<-d> is true if passed a device spec without an explicit directory. |
909 | (VMS) |
910 | |
911 | C<-T> and C<-B> are implemented, but might misclassify Mac text files |
912 | with foreign characters; this is the case will all platforms, but |
913 | affects S<Mac OS> a lot. (S<Mac OS>) |
914 | |
915 | C<-x> (or C<-X>) determine if a file ends in one of the executable |
916 | suffixes. C<-S> is meaningless. (Win32) |
917 | |
b8099c3d |
918 | C<-x> (or C<-X>) determine if a file has an executable file type. |
919 | (S<RISC OS>) |
920 | |
e41182b5 |
921 | =item binmode FILEHANDLE |
922 | |
b8099c3d |
923 | Meaningless. (S<Mac OS>, S<RISC OS>) |
e41182b5 |
924 | |
925 | Reopens file and restores pointer; if function fails, underlying |
926 | filehandle may be closed, or pointer may be in a different position. |
927 | (VMS) |
928 | |
929 | The value returned by C<tell> may be affected after the call, and |
930 | the filehandle may be flushed. (Win32) |
931 | |
932 | =item chmod LIST |
933 | |
934 | Only limited meaning. Disabling/enabling write permission is mapped to |
935 | locking/unlocking the file. (S<Mac OS>) |
936 | |
937 | Only good for changing "owner" read-write access, "group", and "other" |
938 | bits are meaningless. (Win32) |
939 | |
b8099c3d |
940 | Only good for changing "owner" and "other" read-write access. (S<RISC OS>) |
941 | |
e41182b5 |
942 | =item chown LIST |
943 | |
b8099c3d |
944 | Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>) |
e41182b5 |
945 | |
946 | Does nothing, but won't fail. (Win32) |
947 | |
948 | =item chroot FILENAME |
949 | |
950 | =item chroot |
951 | |
b8099c3d |
952 | Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>) |
e41182b5 |
953 | |
954 | =item crypt PLAINTEXT,SALT |
955 | |
956 | May not be available if library or source was not provided when building |
b8099c3d |
957 | perl. (Win32) |
e41182b5 |
958 | |
959 | =item dbmclose HASH |
960 | |
961 | Not implemented. (VMS, Plan9) |
962 | |
963 | =item dbmopen HASH,DBNAME,MODE |
964 | |
965 | Not implemented. (VMS, Plan9) |
966 | |
967 | =item dump LABEL |
968 | |
b8099c3d |
969 | Not useful. (S<Mac OS>, S<RISC OS>) |
e41182b5 |
970 | |
971 | Not implemented. (Win32) |
972 | |
b8099c3d |
973 | Invokes VMS debugger. (VMS) |
e41182b5 |
974 | |
975 | =item exec LIST |
976 | |
977 | Not implemented. (S<Mac OS>) |
978 | |
979 | =item fcntl FILEHANDLE,FUNCTION,SCALAR |
980 | |
981 | Not implemented. (Win32, VMS) |
982 | |
983 | =item flock FILEHANDLE,OPERATION |
984 | |
b8099c3d |
985 | Not implemented (S<Mac OS>, VMS, S<RISC OS>). |
e41182b5 |
986 | |
987 | Available only on Windows NT (not on Windows 95). (Win32) |
988 | |
989 | =item fork |
990 | |
b8099c3d |
991 | Not implemented. (S<Mac OS>, Win32, AmigaOS, S<RISC OS>) |
e41182b5 |
992 | |
993 | =item getlogin |
994 | |
b8099c3d |
995 | Not implemented. (S<Mac OS>, S<RISC OS>) |
e41182b5 |
996 | |
997 | =item getpgrp PID |
998 | |
b8099c3d |
999 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1000 | |
1001 | =item getppid |
1002 | |
b8099c3d |
1003 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1004 | |
1005 | =item getpriority WHICH,WHO |
1006 | |
b8099c3d |
1007 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1008 | |
1009 | =item getpwnam NAME |
1010 | |
1011 | Not implemented. (S<Mac OS>, Win32) |
1012 | |
b8099c3d |
1013 | Not useful. (S<RISC OS>) |
1014 | |
e41182b5 |
1015 | =item getgrnam NAME |
1016 | |
b8099c3d |
1017 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1018 | |
1019 | =item getnetbyname NAME |
1020 | |
1021 | Not implemented. (S<Mac OS>, Win32, Plan9) |
1022 | |
1023 | =item getpwuid UID |
1024 | |
1025 | Not implemented. (S<Mac OS>, Win32) |
1026 | |
b8099c3d |
1027 | Not useful. (S<RISC OS>) |
1028 | |
e41182b5 |
1029 | =item getgrgid GID |
1030 | |
b8099c3d |
1031 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1032 | |
1033 | =item getnetbyaddr ADDR,ADDRTYPE |
1034 | |
1035 | Not implemented. (S<Mac OS>, Win32, Plan9) |
1036 | |
1037 | =item getprotobynumber NUMBER |
1038 | |
1039 | Not implemented. (S<Mac OS>) |
1040 | |
1041 | =item getservbyport PORT,PROTO |
1042 | |
1043 | Not implemented. (S<Mac OS>) |
1044 | |
1045 | =item getpwent |
1046 | |
1047 | Not implemented. (S<Mac OS>, Win32) |
1048 | |
1049 | =item getgrent |
1050 | |
1051 | Not implemented. (S<Mac OS>, Win32, VMS) |
1052 | |
1053 | =item gethostent |
1054 | |
1055 | Not implemented. (S<Mac OS>, Win32) |
1056 | |
1057 | =item getnetent |
1058 | |
1059 | Not implemented. (S<Mac OS>, Win32, Plan9) |
1060 | |
1061 | =item getprotoent |
1062 | |
1063 | Not implemented. (S<Mac OS>, Win32, Plan9) |
1064 | |
1065 | =item getservent |
1066 | |
1067 | Not implemented. (Win32, Plan9) |
1068 | |
1069 | =item setpwent |
1070 | |
b8099c3d |
1071 | Not implemented. (S<Mac OS>, Win32, S<RISC OS>) |
e41182b5 |
1072 | |
1073 | =item setgrent |
1074 | |
b8099c3d |
1075 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1076 | |
1077 | =item sethostent STAYOPEN |
1078 | |
b8099c3d |
1079 | Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>) |
e41182b5 |
1080 | |
1081 | =item setnetent STAYOPEN |
1082 | |
b8099c3d |
1083 | Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>) |
e41182b5 |
1084 | |
1085 | =item setprotoent STAYOPEN |
1086 | |
b8099c3d |
1087 | Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>) |
e41182b5 |
1088 | |
1089 | =item setservent STAYOPEN |
1090 | |
b8099c3d |
1091 | Not implemented. (Plan9, Win32, S<RISC OS>) |
e41182b5 |
1092 | |
1093 | =item endpwent |
1094 | |
1095 | Not implemented. (S<Mac OS>, Win32) |
1096 | |
1097 | =item endgrent |
1098 | |
b8099c3d |
1099 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1100 | |
1101 | =item endhostent |
1102 | |
1103 | Not implemented. (S<Mac OS>, Win32) |
1104 | |
1105 | =item endnetent |
1106 | |
1107 | Not implemented. (S<Mac OS>, Win32, Plan9) |
1108 | |
1109 | =item endprotoent |
1110 | |
1111 | Not implemented. (S<Mac OS>, Win32, Plan9) |
1112 | |
1113 | =item endservent |
1114 | |
1115 | Not implemented. (Plan9, Win32) |
1116 | |
1117 | =item getsockopt SOCKET,LEVEL,OPTNAME |
1118 | |
1119 | Not implemented. (S<Mac OS>, Plan9) |
1120 | |
1121 | =item glob EXPR |
1122 | |
1123 | =item glob |
1124 | |
1125 | Globbing built-in, but only C<*> and C<?> metacharacters are supported. |
1126 | (S<Mac OS>) |
1127 | |
1128 | Features depend on external perlglob.exe or perlglob.bat. May be overridden |
1129 | with something like File::DosGlob, which is recommended. (Win32) |
1130 | |
b8099c3d |
1131 | Globbing built-in, but only C<*> and C<?> metacharacters are supported. |
1132 | Globbing relies on operating system calls, which may return filenames in |
1133 | any order. As most filesystems are case insensitive even "sorted" |
1134 | filenames will not be in case sensitive order. (S<RISC OS>) |
1135 | |
e41182b5 |
1136 | =item ioctl FILEHANDLE,FUNCTION,SCALAR |
1137 | |
1138 | Not implemented. (VMS) |
1139 | |
1140 | Available only for socket handles, and it does what the ioctlsocket() call |
1141 | in the Winsock API does. (Win32) |
1142 | |
b8099c3d |
1143 | Available only for socket handles. (S<RISC OS>) |
1144 | |
e41182b5 |
1145 | =item kill LIST |
1146 | |
b8099c3d |
1147 | Not implemented, hence not useful for taint checking. (S<Mac OS>, S<RISC OS>) |
e41182b5 |
1148 | |
1149 | Available only for process handles returned by the C<system(1, ...)> method of |
b8099c3d |
1150 | spawning a process. (Win32) |
e41182b5 |
1151 | |
1152 | =item link OLDFILE,NEWFILE |
1153 | |
b8099c3d |
1154 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1155 | |
1156 | =item lstat FILEHANDLE |
1157 | |
1158 | =item lstat EXPR |
1159 | |
1160 | =item lstat |
1161 | |
b8099c3d |
1162 | Not implemented. (VMS, S<RISC OS>) |
e41182b5 |
1163 | |
b8099c3d |
1164 | Return values may be bogus. (Win32) |
e41182b5 |
1165 | |
1166 | =item msgctl ID,CMD,ARG |
1167 | |
1168 | =item msgget KEY,FLAGS |
1169 | |
1170 | =item msgsnd ID,MSG,FLAGS |
1171 | |
1172 | =item msgrcv ID,VAR,SIZE,TYPE,FLAGS |
1173 | |
b8099c3d |
1174 | Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>) |
e41182b5 |
1175 | |
1176 | =item open FILEHANDLE,EXPR |
1177 | |
1178 | =item open FILEHANDLE |
1179 | |
1180 | The C<|> variants are only supported if ToolServer is installed. |
1181 | (S<Mac OS>) |
1182 | |
b8099c3d |
1183 | open to C<|-> and C<-|> are unsupported. (S<Mac OS>, Win32, S<RISC OS>) |
e41182b5 |
1184 | |
1185 | =item pipe READHANDLE,WRITEHANDLE |
1186 | |
1187 | Not implemented. (S<Mac OS>) |
1188 | |
1189 | =item readlink EXPR |
1190 | |
1191 | =item readlink |
1192 | |
b8099c3d |
1193 | Not implemented. (Win32, VMS, S<RISC OS>) |
e41182b5 |
1194 | |
1195 | =item select RBITS,WBITS,EBITS,TIMEOUT |
1196 | |
1197 | Only implemented on sockets. (Win32) |
1198 | |
b8099c3d |
1199 | Only reliable on sockets. (S<RISC OS>) |
1200 | |
e41182b5 |
1201 | =item semctl ID,SEMNUM,CMD,ARG |
1202 | |
1203 | =item semget KEY,NSEMS,FLAGS |
1204 | |
1205 | =item semop KEY,OPSTRING |
1206 | |
b8099c3d |
1207 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1208 | |
1209 | =item setpgrp PID,PGRP |
1210 | |
b8099c3d |
1211 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1212 | |
1213 | =item setpriority WHICH,WHO,PRIORITY |
1214 | |
b8099c3d |
1215 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1216 | |
1217 | =item setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL |
1218 | |
1219 | Not implemented. (S<Mac OS>, Plan9) |
1220 | |
1221 | =item shmctl ID,CMD,ARG |
1222 | |
1223 | =item shmget KEY,SIZE,FLAGS |
1224 | |
1225 | =item shmread ID,VAR,POS,SIZE |
1226 | |
1227 | =item shmwrite ID,STRING,POS,SIZE |
1228 | |
b8099c3d |
1229 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1230 | |
1231 | =item socketpair SOCKET1,SOCKET2,DOMAIN,TYPE,PROTOCOL |
1232 | |
b8099c3d |
1233 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1234 | |
1235 | =item stat FILEHANDLE |
1236 | |
1237 | =item stat EXPR |
1238 | |
1239 | =item stat |
1240 | |
1241 | mtime and atime are the same thing, and ctime is creation time instead of |
1242 | inode change time. (S<Mac OS>) |
1243 | |
1244 | device and inode are not meaningful. (Win32) |
1245 | |
1246 | device and inode are not necessarily reliable. (VMS) |
1247 | |
b8099c3d |
1248 | mtime, atime and ctime all return the last modification time. Device and |
1249 | inode are not necessarily reliable. (S<RISC OS>) |
1250 | |
e41182b5 |
1251 | =item symlink OLDFILE,NEWFILE |
1252 | |
b8099c3d |
1253 | Not implemented. (Win32, VMS, S<RISC OS>) |
e41182b5 |
1254 | |
1255 | =item syscall LIST |
1256 | |
b8099c3d |
1257 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1258 | |
f34d0673 |
1259 | =item sysopen FILEHANDLE,FILENAME,MODE,PERMS |
1260 | |
dd9f0070 |
1261 | The traditional "0", "1", and "2" MODEs are implemented with different |
f34d0673 |
1262 | numeric values on some systems. The flags exported by C<Fcntl> should work |
1263 | everywhere though. (S<Mac OS>, OS/390) |
1264 | |
e41182b5 |
1265 | =item system LIST |
1266 | |
1267 | Only implemented if ToolServer is installed. (S<Mac OS>) |
1268 | |
1269 | As an optimization, may not call the command shell specified in |
1270 | C<$ENV{PERL5SHELL}>. C<system(1, @args)> spawns an external |
1271 | process and immediately returns its process designator, without |
1272 | waiting for it to terminate. Return value may be used subsequently |
1273 | in C<wait> or C<waitpid>. (Win32) |
1274 | |
b8099c3d |
1275 | There is no shell to process metacharacters, and the native standard is |
1276 | to pass a command line terminated by "\n" "\r" or "\0" to the spawned |
1277 | program. Redirection such as C<E<gt> foo> is performed (if at all) by |
1278 | the run time library of the spawned program. C<system> I<list> will call |
1279 | the Unix emulation library's C<exec> emulation, which attempts to provide |
1280 | emulation of the stdin, stdout, stderr in force in the parent, providing |
1281 | the child program uses a compatible version of the emulation library. |
1282 | I<scalar> will call the native command line direct and no such emulation |
1283 | of a child Unix program will exists. Mileage B<will> vary. (S<RISC OS>) |
1284 | |
e41182b5 |
1285 | =item times |
1286 | |
1287 | Only the first entry returned is nonzero. (S<Mac OS>) |
1288 | |
1289 | "cumulative" times will be bogus. On anything other than Windows NT, |
1290 | "system" time will be bogus, and "user" time is actually the time |
1291 | returned by the clock() function in the C runtime library. (Win32) |
1292 | |
b8099c3d |
1293 | Not useful. (S<RISC OS>) |
1294 | |
e41182b5 |
1295 | =item truncate FILEHANDLE,LENGTH |
1296 | |
1297 | =item truncate EXPR,LENGTH |
1298 | |
1299 | Not implemented. (VMS) |
1300 | |
1301 | =item umask EXPR |
1302 | |
1303 | =item umask |
1304 | |
1305 | Returns undef where unavailable, as of version 5.005. |
1306 | |
1307 | =item utime LIST |
1308 | |
b8099c3d |
1309 | Only the modification time is updated. (S<Mac OS>, VMS, S<RISC OS>) |
e41182b5 |
1310 | |
1311 | May not behave as expected. (Win32) |
1312 | |
1313 | =item wait |
1314 | |
1315 | =item waitpid PID,FLAGS |
1316 | |
1317 | Not implemented. (S<Mac OS>) |
1318 | |
1319 | Can only be applied to process handles returned for processes spawned |
1320 | using C<system(1, ...)>. (Win32) |
1321 | |
b8099c3d |
1322 | Not useful. (S<RISC OS>) |
1323 | |
e41182b5 |
1324 | =back |
1325 | |
b8099c3d |
1326 | =head1 CHANGES |
1327 | |
1328 | =over 4 |
1329 | |
dd9f0070 |
1330 | =item 1.32, 05 August 1998 |
1331 | |
1332 | Integrate more minor changes. |
1333 | |
b8099c3d |
1334 | =item 1.30, 03 August 1998 |
1335 | |
1336 | Major update for RISC OS, other minor changes. |
1337 | |
1338 | =item 1.23, 10 July 1998 |
1339 | |
1340 | First public release with perl5.005. |
1341 | |
1342 | =back |
e41182b5 |
1343 | |
1344 | =head1 AUTHORS / CONTRIBUTORS |
1345 | |
dd9f0070 |
1346 | Abigail E<lt>abigail@fnx.comE<gt>, |
1347 | Charles Bailey E<lt>bailey@genetics.upenn.eduE<gt>, |
1348 | Graham Barr E<lt>gbarr@pobox.comE<gt>, |
e41182b5 |
1349 | Tom Christiansen E<lt>tchrist@perl.comE<gt>, |
dd9f0070 |
1350 | Nicholas Clark E<lt>Nicholas.Clark@liverpool.ac.ukE<gt>, |
1351 | Andy Dougherty E<lt>doughera@lafcol.lafayette.eduE<gt>, |
1352 | Dominic Dunlop E<lt>domo@vo.luE<gt>, |
1353 | M.J.T. Guy E<lt>mjtg@cus.cam.ac.ukE<gt>, |
1354 | Luther Huffman E<lt>lutherh@stratcom.comE<gt>, |
1355 | Nick Ing-Simmons E<lt>nick@ni-s.u-net.comE<gt>, |
1356 | Andreas J. Koenig E<lt>koenig@kulturbox.deE<gt>, |
1357 | Andrew M. Langmead E<lt>aml@world.std.comE<gt>, |
e41182b5 |
1358 | Paul Moore E<lt>Paul.Moore@uk.origin-it.comE<gt>, |
dd9f0070 |
1359 | Chris Nandor E<lt>pudge@pobox.comE<gt>, |
e41182b5 |
1360 | Matthias Neercher E<lt>neeri@iis.ee.ethz.chE<gt>, |
e41182b5 |
1361 | Gary Ng E<lt>71564.1743@CompuServe.COME<gt>, |
e41182b5 |
1362 | Tom Phoenix E<lt>rootbeer@teleport.comE<gt>, |
dd9f0070 |
1363 | Peter Prymmer E<lt>pvhp@forte.comE<gt>, |
e41182b5 |
1364 | Hugo van der Sanden E<lt>h.sanden@elsevier.nlE<gt>, |
dd9f0070 |
1365 | Gurusamy Sarathy E<lt>gsar@umich.eduE<gt>, |
1366 | Paul J. Schinder E<lt>schinder@pobox.comE<gt>, |
e41182b5 |
1367 | Dan Sugalski E<lt>sugalskd@ous.eduE<gt>, |
dd9f0070 |
1368 | Nathan Torkington E<lt>gnat@frii.comE<gt>. |
e41182b5 |
1369 | |
1370 | This document is maintained by Chris Nandor. |
1371 | |
1372 | =head1 VERSION |
1373 | |
dd9f0070 |
1374 | Version 1.32, last modified 05 August 1998. |
e41182b5 |
1375 | |