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1 | =head1 NAME |
2 | ||
3 | perlport - Writing portable Perl | |
4 | ||
e41182b5 GS |
5 | =head1 DESCRIPTION |
6 | ||
b7df3edc GS |
7 | Perl runs on numerous operating systems. While most of them share |
8 | much in common, they also have their own unique features. | |
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9 | |
10 | This document is meant to help you to find out what constitutes portable | |
b7df3edc | 11 | Perl code. That way once you make a decision to write portably, |
e41182b5 GS |
12 | you know where the lines are drawn, and you can stay within them. |
13 | ||
b7df3edc GS |
14 | There is a tradeoff between taking full advantage of one particular |
15 | type of computer and taking advantage of a full range of them. | |
16 | Naturally, as you broaden your range and become more diverse, the | |
17 | common factors drop, and you are left with an increasingly smaller | |
18 | area of common ground in which you can operate to accomplish a | |
19 | particular task. Thus, when you begin attacking a problem, it is | |
20 | important to consider under which part of the tradeoff curve you | |
21 | want to operate. Specifically, you must decide whether it is | |
22 | important that the task that you are coding have the full generality | |
23 | of being portable, or whether to just get the job done right now. | |
24 | This is the hardest choice to be made. The rest is easy, because | |
25 | Perl provides many choices, whichever way you want to approach your | |
0a47030a GS |
26 | problem. |
27 | ||
28 | Looking at it another way, writing portable code is usually about | |
b7df3edc GS |
29 | willfully limiting your available choices. Naturally, it takes |
30 | discipline and sacrifice to do that. The product of portability | |
31 | and convenience may be a constant. You have been warned. | |
e41182b5 GS |
32 | |
33 | Be aware of two important points: | |
34 | ||
35 | =over 4 | |
36 | ||
37 | =item Not all Perl programs have to be portable | |
38 | ||
b7df3edc | 39 | There is no reason you should not use Perl as a language to glue Unix |
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40 | tools together, or to prototype a Macintosh application, or to manage the |
41 | Windows registry. If it makes no sense to aim for portability for one | |
42 | reason or another in a given program, then don't bother. | |
43 | ||
b7df3edc | 44 | =item Nearly all of Perl already I<is> portable |
e41182b5 GS |
45 | |
46 | Don't be fooled into thinking that it is hard to create portable Perl | |
47 | code. It isn't. Perl tries its level-best to bridge the gaps between | |
48 | what's available on different platforms, and all the means available to | |
49 | use those features. Thus almost all Perl code runs on any machine | |
6ab3f9cb | 50 | without modification. But there are some significant issues in |
e41182b5 GS |
51 | writing portable code, and this document is entirely about those issues. |
52 | ||
53 | =back | |
54 | ||
b7df3edc GS |
55 | Here's the general rule: When you approach a task commonly done |
56 | using a whole range of platforms, think about writing portable | |
e41182b5 GS |
57 | code. That way, you don't sacrifice much by way of the implementation |
58 | choices you can avail yourself of, and at the same time you can give | |
59 | your users lots of platform choices. On the other hand, when you have to | |
60 | take advantage of some unique feature of a particular platform, as is | |
61 | often the case with systems programming (whether for Unix, Windows, | |
62 | S<Mac OS>, VMS, etc.), consider writing platform-specific code. | |
63 | ||
b7df3edc GS |
64 | When the code will run on only two or three operating systems, you |
65 | may need to consider only the differences of those particular systems. | |
66 | The important thing is to decide where the code will run and to be | |
0a47030a GS |
67 | deliberate in your decision. |
68 | ||
69 | The material below is separated into three main sections: main issues of | |
70 | portability (L<"ISSUES">, platform-specific issues (L<"PLATFORMS">, and | |
b7df3edc | 71 | built-in perl functions that behave differently on various ports |
0a47030a | 72 | (L<"FUNCTION IMPLEMENTATIONS">. |
e41182b5 GS |
73 | |
74 | This information should not be considered complete; it includes possibly | |
b8099c3d | 75 | transient information about idiosyncrasies of some of the ports, almost |
b7df3edc | 76 | all of which are in a state of constant evolution. Thus, this material |
e41182b5 | 77 | should be considered a perpetual work in progress |
c47ff5f1 | 78 | (<IMG SRC="yellow_sign.gif" ALT="Under Construction">). |
e41182b5 | 79 | |
e41182b5 GS |
80 | =head1 ISSUES |
81 | ||
82 | =head2 Newlines | |
83 | ||
638bc118 | 84 | In most operating systems, lines in files are terminated by newlines. |
e41182b5 | 85 | Just what is used as a newline may vary from OS to OS. Unix |
b7df3edc | 86 | traditionally uses C<\012>, one type of DOSish I/O uses C<\015\012>, |
e41182b5 GS |
87 | and S<Mac OS> uses C<\015>. |
88 | ||
b7df3edc GS |
89 | Perl uses C<\n> to represent the "logical" newline, where what is |
90 | logical may depend on the platform in use. In MacPerl, C<\n> always | |
91 | means C<\015>. In DOSish perls, C<\n> usually means C<\012>, but | |
92 | when accessing a file in "text" mode, STDIO translates it to (or | |
56d7751a | 93 | from) C<\015\012>, depending on whether you're reading or writing. |
b7df3edc GS |
94 | Unix does the same thing on ttys in canonical mode. C<\015\012> |
95 | is commonly referred to as CRLF. | |
96 | ||
5b3eff12 MS |
97 | A common cause of unportable programs is the misuse of chop() to trim |
98 | newlines: | |
99 | ||
100 | # XXX UNPORTABLE! | |
101 | while(<FILE>) { | |
102 | chop; | |
103 | @array = split(/:/); | |
104 | #... | |
105 | } | |
106 | ||
107 | You can get away with this on Unix and MacOS (they have a single | |
108 | character end-of-line), but the same program will break under DOSish | |
109 | perls because you're only chop()ing half the end-of-line. Instead, | |
110 | chomp() should be used to trim newlines. The Dunce::Files module can | |
111 | help audit your code for misuses of chop(). | |
112 | ||
113 | When dealing with binary files (or text files in binary mode) be sure | |
114 | to explicitly set $/ to the appropriate value for your file format | |
115 | before using chomp(). | |
116 | ||
b7df3edc GS |
117 | Because of the "text" mode translation, DOSish perls have limitations |
118 | in using C<seek> and C<tell> on a file accessed in "text" mode. | |
119 | Stick to C<seek>-ing to locations you got from C<tell> (and no | |
120 | others), and you are usually free to use C<seek> and C<tell> even | |
121 | in "text" mode. Using C<seek> or C<tell> or other file operations | |
122 | may be non-portable. If you use C<binmode> on a file, however, you | |
123 | can usually C<seek> and C<tell> with arbitrary values in safety. | |
e41182b5 GS |
124 | |
125 | A common misconception in socket programming is that C<\n> eq C<\012> | |
0a47030a | 126 | everywhere. When using protocols such as common Internet protocols, |
e41182b5 GS |
127 | C<\012> and C<\015> are called for specifically, and the values of |
128 | the logical C<\n> and C<\r> (carriage return) are not reliable. | |
129 | ||
130 | print SOCKET "Hi there, client!\r\n"; # WRONG | |
131 | print SOCKET "Hi there, client!\015\012"; # RIGHT | |
132 | ||
0a47030a GS |
133 | However, using C<\015\012> (or C<\cM\cJ>, or C<\x0D\x0A>) can be tedious |
134 | and unsightly, as well as confusing to those maintaining the code. As | |
6ab3f9cb | 135 | such, the Socket module supplies the Right Thing for those who want it. |
e41182b5 GS |
136 | |
137 | use Socket qw(:DEFAULT :crlf); | |
138 | print SOCKET "Hi there, client!$CRLF" # RIGHT | |
139 | ||
6ab3f9cb | 140 | When reading from a socket, remember that the default input record |
b7df3edc GS |
141 | separator C<$/> is C<\n>, but robust socket code will recognize as |
142 | either C<\012> or C<\015\012> as end of line: | |
e41182b5 GS |
143 | |
144 | while (<SOCKET>) { | |
145 | # ... | |
146 | } | |
147 | ||
b7df3edc GS |
148 | Because both CRLF and LF end in LF, the input record separator can |
149 | be set to LF and any CR stripped later. Better to write: | |
e41182b5 GS |
150 | |
151 | use Socket qw(:DEFAULT :crlf); | |
152 | local($/) = LF; # not needed if $/ is already \012 | |
153 | ||
154 | while (<SOCKET>) { | |
155 | s/$CR?$LF/\n/; # not sure if socket uses LF or CRLF, OK | |
156 | # s/\015?\012/\n/; # same thing | |
157 | } | |
158 | ||
b7df3edc GS |
159 | This example is preferred over the previous one--even for Unix |
160 | platforms--because now any C<\015>'s (C<\cM>'s) are stripped out | |
e41182b5 GS |
161 | (and there was much rejoicing). |
162 | ||
6ab3f9cb | 163 | Similarly, functions that return text data--such as a function that |
b7df3edc GS |
164 | fetches a web page--should sometimes translate newlines before |
165 | returning the data, if they've not yet been translated to the local | |
166 | newline representation. A single line of code will often suffice: | |
2ee0eb3c | 167 | |
b7df3edc GS |
168 | $data =~ s/\015?\012/\n/g; |
169 | return $data; | |
2ee0eb3c | 170 | |
6ab3f9cb GS |
171 | Some of this may be confusing. Here's a handy reference to the ASCII CR |
172 | and LF characters. You can print it out and stick it in your wallet. | |
173 | ||
174 | LF == \012 == \x0A == \cJ == ASCII 10 | |
175 | CR == \015 == \x0D == \cM == ASCII 13 | |
176 | ||
177 | | Unix | DOS | Mac | | |
178 | --------------------------- | |
179 | \n | LF | LF | CR | | |
180 | \r | CR | CR | LF | | |
181 | \n * | LF | CRLF | CR | | |
182 | \r * | CR | CR | LF | | |
183 | --------------------------- | |
184 | * text-mode STDIO | |
185 | ||
b7df3edc GS |
186 | The Unix column assumes that you are not accessing a serial line |
187 | (like a tty) in canonical mode. If you are, then CR on input becomes | |
188 | "\n", and "\n" on output becomes CRLF. | |
189 | ||
6ab3f9cb GS |
190 | These are just the most common definitions of C<\n> and C<\r> in Perl. |
191 | There may well be others. | |
192 | ||
322422de GS |
193 | =head2 Numbers endianness and Width |
194 | ||
195 | Different CPUs store integers and floating point numbers in different | |
196 | orders (called I<endianness>) and widths (32-bit and 64-bit being the | |
b7df3edc GS |
197 | most common today). This affects your programs when they attempt to transfer |
198 | numbers in binary format from one CPU architecture to another, | |
199 | usually either "live" via network connection, or by storing the | |
200 | numbers to secondary storage such as a disk file or tape. | |
322422de | 201 | |
b7df3edc | 202 | Conflicting storage orders make utter mess out of the numbers. If a |
d1e3b762 | 203 | little-endian host (Intel, VAX) stores 0x12345678 (305419896 in |
b84d4f81 JH |
204 | decimal), a big-endian host (Motorola, Sparc, PA) reads it as |
205 | 0x78563412 (2018915346 in decimal). Alpha and MIPS can be either: | |
206 | Digital/Compaq used/uses them in little-endian mode; SGI/Cray uses | |
207 | them in big-endian mode. To avoid this problem in network (socket) | |
208 | connections use the C<pack> and C<unpack> formats C<n> and C<N>, the | |
209 | "network" orders. These are guaranteed to be portable. | |
322422de | 210 | |
d1e3b762 GS |
211 | You can explore the endianness of your platform by unpacking a |
212 | data structure packed in native format such as: | |
213 | ||
214 | print unpack("h*", pack("s2", 1, 2)), "\n"; | |
215 | # '10002000' on e.g. Intel x86 or Alpha 21064 in little-endian mode | |
216 | # '00100020' on e.g. Motorola 68040 | |
217 | ||
218 | If you need to distinguish between endian architectures you could use | |
219 | either of the variables set like so: | |
220 | ||
221 | $is_big_endian = unpack("h*", pack("s", 1)) =~ /01/; | |
4375e838 | 222 | $is_little_endian = unpack("h*", pack("s", 1)) =~ /^1/; |
d1e3b762 | 223 | |
b7df3edc GS |
224 | Differing widths can cause truncation even between platforms of equal |
225 | endianness. The platform of shorter width loses the upper parts of the | |
322422de GS |
226 | number. There is no good solution for this problem except to avoid |
227 | transferring or storing raw binary numbers. | |
228 | ||
b7df3edc | 229 | One can circumnavigate both these problems in two ways. Either |
322422de | 230 | transfer and store numbers always in text format, instead of raw |
b7df3edc | 231 | binary, or else consider using modules like Data::Dumper (included in |
83df6a1d JH |
232 | the standard distribution as of Perl 5.005) and Storable (included as |
233 | of perl 5.8). Keeping all data as text significantly simplifies matters. | |
322422de | 234 | |
433acd8a | 235 | =head2 Files and Filesystems |
e41182b5 GS |
236 | |
237 | Most platforms these days structure files in a hierarchical fashion. | |
b7df3edc | 238 | So, it is reasonably safe to assume that all platforms support the |
6ab3f9cb | 239 | notion of a "path" to uniquely identify a file on the system. How |
b7df3edc | 240 | that path is really written, though, differs considerably. |
e41182b5 | 241 | |
4375e838 | 242 | Although similar, file path specifications differ between Unix, |
b7df3edc GS |
243 | Windows, S<Mac OS>, OS/2, VMS, VOS, S<RISC OS>, and probably others. |
244 | Unix, for example, is one of the few OSes that has the elegant idea | |
245 | of a single root directory. | |
322422de | 246 | |
6ab3f9cb GS |
247 | DOS, OS/2, VMS, VOS, and Windows can work similarly to Unix with C</> |
248 | as path separator, or in their own idiosyncratic ways (such as having | |
249 | several root directories and various "unrooted" device files such NIL: | |
250 | and LPT:). | |
322422de GS |
251 | |
252 | S<Mac OS> uses C<:> as a path separator instead of C</>. | |
253 | ||
6ab3f9cb GS |
254 | The filesystem may support neither hard links (C<link>) nor |
255 | symbolic links (C<symlink>, C<readlink>, C<lstat>). | |
433acd8a | 256 | |
6ab3f9cb | 257 | The filesystem may support neither access timestamp nor change |
433acd8a JH |
258 | timestamp (meaning that about the only portable timestamp is the |
259 | modification timestamp), or one second granularity of any timestamps | |
260 | (e.g. the FAT filesystem limits the time granularity to two seconds). | |
261 | ||
495c5fdc PG |
262 | VOS perl can emulate Unix filenames with C</> as path separator. The |
263 | native pathname characters greater-than, less-than, number-sign, and | |
264 | percent-sign are always accepted. | |
265 | ||
6ab3f9cb | 266 | S<RISC OS> perl can emulate Unix filenames with C</> as path |
322422de | 267 | separator, or go native and use C<.> for path separator and C<:> to |
6ab3f9cb | 268 | signal filesystems and disk names. |
e41182b5 | 269 | |
a1667ba3 JH |
270 | Don't assume UNIX filesystem access semantics: that read, write, |
271 | and execute are all the permissions there are, and even if they exist, | |
272 | that their semantics (for example what do r, w, and x mean on | |
273 | a directory) are the UNIX ones. The various UNIX/POSIX compatibility | |
274 | layers usually try to make interfaces like chmod() work, but sometimes | |
275 | there simply is no good mapping. | |
276 | ||
b7df3edc GS |
277 | If all this is intimidating, have no (well, maybe only a little) |
278 | fear. There are modules that can help. The File::Spec modules | |
279 | provide methods to do the Right Thing on whatever platform happens | |
280 | to be running the program. | |
e41182b5 | 281 | |
6ab3f9cb GS |
282 | use File::Spec::Functions; |
283 | chdir(updir()); # go up one directory | |
284 | $file = catfile(curdir(), 'temp', 'file.txt'); | |
e41182b5 GS |
285 | # on Unix and Win32, './temp/file.txt' |
286 | # on Mac OS, ':temp:file.txt' | |
d1e3b762 | 287 | # on VMS, '[.temp]file.txt' |
e41182b5 | 288 | |
b7df3edc | 289 | File::Spec is available in the standard distribution as of version |
d1e3b762 GS |
290 | 5.004_05. File::Spec::Functions is only in File::Spec 0.7 and later, |
291 | and some versions of perl come with version 0.6. If File::Spec | |
292 | is not updated to 0.7 or later, you must use the object-oriented | |
293 | interface from File::Spec (or upgrade File::Spec). | |
e41182b5 | 294 | |
b7df3edc GS |
295 | In general, production code should not have file paths hardcoded. |
296 | Making them user-supplied or read from a configuration file is | |
297 | better, keeping in mind that file path syntax varies on different | |
298 | machines. | |
e41182b5 GS |
299 | |
300 | This is especially noticeable in scripts like Makefiles and test suites, | |
301 | which often assume C</> as a path separator for subdirectories. | |
302 | ||
b7df3edc | 303 | Also of use is File::Basename from the standard distribution, which |
e41182b5 GS |
304 | splits a pathname into pieces (base filename, full path to directory, |
305 | and file suffix). | |
306 | ||
19799a22 | 307 | Even when on a single platform (if you can call Unix a single platform), |
b7df3edc | 308 | remember not to count on the existence or the contents of particular |
3c075c7d | 309 | system-specific files or directories, like F</etc/passwd>, |
b7df3edc GS |
310 | F</etc/sendmail.conf>, F</etc/resolv.conf>, or even F</tmp/>. For |
311 | example, F</etc/passwd> may exist but not contain the encrypted | |
312 | passwords, because the system is using some form of enhanced security. | |
313 | Or it may not contain all the accounts, because the system is using NIS. | |
3c075c7d | 314 | If code does need to rely on such a file, include a description of the |
b7df3edc | 315 | file and its format in the code's documentation, then make it easy for |
3c075c7d CN |
316 | the user to override the default location of the file. |
317 | ||
b7df3edc GS |
318 | Don't assume a text file will end with a newline. They should, |
319 | but people forget. | |
e41182b5 | 320 | |
dd9f0070 | 321 | Do not have two files of the same name with different case, like |
3c075c7d | 322 | F<test.pl> and F<Test.pl>, as many platforms have case-insensitive |
dd9f0070 | 323 | filenames. Also, try not to have non-word characters (except for C<.>) |
0a47030a | 324 | in the names, and keep them to the 8.3 convention, for maximum |
b7df3edc | 325 | portability, onerous a burden though this may appear. |
dd9f0070 | 326 | |
b7df3edc GS |
327 | Likewise, when using the AutoSplit module, try to keep your functions to |
328 | 8.3 naming and case-insensitive conventions; or, at the least, | |
dd9f0070 CN |
329 | make it so the resulting files have a unique (case-insensitively) |
330 | first 8 characters. | |
331 | ||
b7df3edc GS |
332 | Whitespace in filenames is tolerated on most systems, but not all. |
333 | Many systems (DOS, VMS) cannot have more than one C<.> in their filenames. | |
433acd8a | 334 | |
c47ff5f1 GS |
335 | Don't assume C<< > >> won't be the first character of a filename. |
336 | Always use C<< < >> explicitly to open a file for reading, | |
b7df3edc | 337 | unless you want the user to be able to specify a pipe open. |
0a47030a | 338 | |
6ab3f9cb | 339 | open(FILE, "< $existing_file") or die $!; |
0a47030a | 340 | |
6ab3f9cb GS |
341 | If filenames might use strange characters, it is safest to open it |
342 | with C<sysopen> instead of C<open>. C<open> is magic and can | |
c47ff5f1 | 343 | translate characters like C<< > >>, C<< < >>, and C<|>, which may |
b7df3edc | 344 | be the wrong thing to do. (Sometimes, though, it's the right thing.) |
e41182b5 GS |
345 | |
346 | =head2 System Interaction | |
347 | ||
b7df3edc GS |
348 | Not all platforms provide a command line. These are usually platforms |
349 | that rely primarily on a Graphical User Interface (GUI) for user | |
350 | interaction. A program requiring a command line interface might | |
351 | not work everywhere. This is probably for the user of the program | |
352 | to deal with, so don't stay up late worrying about it. | |
e41182b5 | 353 | |
b7df3edc GS |
354 | Some platforms can't delete or rename files held open by the system. |
355 | Remember to C<close> files when you are done with them. Don't | |
356 | C<unlink> or C<rename> an open file. Don't C<tie> or C<open> a | |
357 | file already tied or opened; C<untie> or C<close> it first. | |
e41182b5 | 358 | |
0a47030a GS |
359 | Don't open the same file more than once at a time for writing, as some |
360 | operating systems put mandatory locks on such files. | |
361 | ||
73e9292c JH |
362 | Don't assume that write/modify permission on a directory gives the |
363 | right to add or delete files/directories in that directory. That is | |
364 | filesystem specific: in some filesystems you need write/modify | |
365 | permission also (or even just) in the file/directory itself. In some | |
366 | filesystems (AFS, DFS) the permission to add/delete directory entries | |
367 | is a completely separate permission. | |
368 | ||
369 | Don't assume that a single C<unlink> completely gets rid of the file: | |
370 | some filesystems (most notably the ones in VMS) have versioned | |
371 | filesystems, and unlink() removes only the most recent one (it doesn't | |
372 | remove all the versions because by default the native tools on those | |
373 | platforms remove just the most recent version, too). The portable | |
374 | idiom to remove all the versions of a file is | |
375 | ||
94bb614c | 376 | 1 while unlink "file"; |
73e9292c JH |
377 | |
378 | This will terminate if the file is undeleteable for some reason | |
379 | (protected, not there, and so on). | |
380 | ||
e41182b5 | 381 | Don't count on a specific environment variable existing in C<%ENV>. |
0a47030a | 382 | Don't count on C<%ENV> entries being case-sensitive, or even |
4a0d0822 | 383 | case-preserving. Don't try to clear %ENV by saying C<%ENV = ();>, or, |
6be8f7a6 | 384 | if you really have to, make it conditional on C<$^O ne 'VMS'> since in |
4a0d0822 JH |
385 | VMS the C<%ENV> table is much more than a per-process key-value string |
386 | table. | |
e41182b5 | 387 | |
d1e3b762 | 388 | Don't count on signals or C<%SIG> for anything. |
e41182b5 GS |
389 | |
390 | Don't count on filename globbing. Use C<opendir>, C<readdir>, and | |
391 | C<closedir> instead. | |
392 | ||
b8099c3d | 393 | Don't count on per-program environment variables, or per-program current |
dd9f0070 | 394 | directories. |
b8099c3d | 395 | |
3c075c7d CN |
396 | Don't count on specific values of C<$!>. |
397 | ||
e41182b5 GS |
398 | =head2 Interprocess Communication (IPC) |
399 | ||
b7df3edc GS |
400 | In general, don't directly access the system in code meant to be |
401 | portable. That means, no C<system>, C<exec>, C<fork>, C<pipe>, | |
402 | C<``>, C<qx//>, C<open> with a C<|>, nor any of the other things | |
403 | that makes being a perl hacker worth being. | |
e41182b5 GS |
404 | |
405 | Commands that launch external processes are generally supported on | |
b7df3edc GS |
406 | most platforms (though many of them do not support any type of |
407 | forking). The problem with using them arises from what you invoke | |
408 | them on. External tools are often named differently on different | |
4375e838 | 409 | platforms, may not be available in the same location, might accept |
b7df3edc GS |
410 | different arguments, can behave differently, and often present their |
411 | results in a platform-dependent way. Thus, you should seldom depend | |
412 | on them to produce consistent results. (Then again, if you're calling | |
413 | I<netstat -a>, you probably don't expect it to run on both Unix and CP/M.) | |
e41182b5 | 414 | |
b7df3edc | 415 | One especially common bit of Perl code is opening a pipe to B<sendmail>: |
e41182b5 | 416 | |
b7df3edc GS |
417 | open(MAIL, '|/usr/lib/sendmail -t') |
418 | or die "cannot fork sendmail: $!"; | |
e41182b5 GS |
419 | |
420 | This is fine for systems programming when sendmail is known to be | |
421 | available. But it is not fine for many non-Unix systems, and even | |
422 | some Unix systems that may not have sendmail installed. If a portable | |
b7df3edc GS |
423 | solution is needed, see the various distributions on CPAN that deal |
424 | with it. Mail::Mailer and Mail::Send in the MailTools distribution are | |
425 | commonly used, and provide several mailing methods, including mail, | |
426 | sendmail, and direct SMTP (via Net::SMTP) if a mail transfer agent is | |
427 | not available. Mail::Sendmail is a standalone module that provides | |
428 | simple, platform-independent mailing. | |
429 | ||
430 | The Unix System V IPC (C<msg*(), sem*(), shm*()>) is not available | |
431 | even on all Unix platforms. | |
e41182b5 | 432 | |
a81e5e2e A |
433 | Do not use either the bare result of C<pack("N", 10, 20, 30, 40)> or |
434 | bare v-strings (such as C<v10.20.30.40>) to represent IPv4 addresses: | |
435 | both forms just pack the four bytes into network order. That this | |
436 | would be equal to the C language C<in_addr> struct (which is what the | |
437 | socket code internally uses) is not guaranteed. To be portable use | |
438 | the routines of the Socket extension, such as C<inet_aton()>, | |
439 | C<inet_ntoa()>, and C<sockaddr_in()>. | |
6b2463a0 | 440 | |
e41182b5 | 441 | The rule of thumb for portable code is: Do it all in portable Perl, or |
0a47030a GS |
442 | use a module (that may internally implement it with platform-specific |
443 | code, but expose a common interface). | |
e41182b5 | 444 | |
e41182b5 GS |
445 | =head2 External Subroutines (XS) |
446 | ||
b7df3edc | 447 | XS code can usually be made to work with any platform, but dependent |
e41182b5 GS |
448 | libraries, header files, etc., might not be readily available or |
449 | portable, or the XS code itself might be platform-specific, just as Perl | |
450 | code might be. If the libraries and headers are portable, then it is | |
451 | normally reasonable to make sure the XS code is portable, too. | |
452 | ||
b7df3edc GS |
453 | A different type of portability issue arises when writing XS code: |
454 | availability of a C compiler on the end-user's system. C brings | |
455 | with it its own portability issues, and writing XS code will expose | |
456 | you to some of those. Writing purely in Perl is an easier way to | |
e41182b5 GS |
457 | achieve portability. |
458 | ||
e41182b5 GS |
459 | =head2 Standard Modules |
460 | ||
461 | In general, the standard modules work across platforms. Notable | |
6ab3f9cb | 462 | exceptions are the CPAN module (which currently makes connections to external |
e41182b5 | 463 | programs that may not be available), platform-specific modules (like |
6ab3f9cb | 464 | ExtUtils::MM_VMS), and DBM modules. |
e41182b5 | 465 | |
b7df3edc | 466 | There is no one DBM module available on all platforms. |
6ab3f9cb GS |
467 | SDBM_File and the others are generally available on all Unix and DOSish |
468 | ports, but not in MacPerl, where only NBDM_File and DB_File are | |
0a47030a | 469 | available. |
e41182b5 GS |
470 | |
471 | The good news is that at least some DBM module should be available, and | |
6ab3f9cb | 472 | AnyDBM_File will use whichever module it can find. Of course, then |
b7df3edc GS |
473 | the code needs to be fairly strict, dropping to the greatest common |
474 | factor (e.g., not exceeding 1K for each record), so that it will | |
6ab3f9cb | 475 | work with any DBM module. See L<AnyDBM_File> for more details. |
e41182b5 | 476 | |
e41182b5 GS |
477 | =head2 Time and Date |
478 | ||
0a47030a | 479 | The system's notion of time of day and calendar date is controlled in |
b7df3edc | 480 | widely different ways. Don't assume the timezone is stored in C<$ENV{TZ}>, |
0a47030a GS |
481 | and even if it is, don't assume that you can control the timezone through |
482 | that variable. | |
e41182b5 | 483 | |
322422de | 484 | Don't assume that the epoch starts at 00:00:00, January 1, 1970, |
6ab3f9cb GS |
485 | because that is OS- and implementation-specific. It is better to store a date |
486 | in an unambiguous representation. The ISO-8601 standard defines | |
487 | "YYYY-MM-DD" as the date format. A text representation (like "1987-12-18") | |
488 | can be easily converted into an OS-specific value using a module like | |
489 | Date::Parse. An array of values, such as those returned by | |
322422de | 490 | C<localtime>, can be converted to an OS-specific representation using |
6ab3f9cb | 491 | Time::Local. |
322422de | 492 | |
19799a22 GS |
493 | When calculating specific times, such as for tests in time or date modules, |
494 | it may be appropriate to calculate an offset for the epoch. | |
b7df3edc | 495 | |
19799a22 GS |
496 | require Time::Local; |
497 | $offset = Time::Local::timegm(0, 0, 0, 1, 0, 70); | |
b7df3edc | 498 | |
19799a22 GS |
499 | The value for C<$offset> in Unix will be C<0>, but in Mac OS will be |
500 | some large number. C<$offset> can then be added to a Unix time value | |
501 | to get what should be the proper value on any system. | |
322422de GS |
502 | |
503 | =head2 Character sets and character encoding | |
504 | ||
b7df3edc GS |
505 | Assume little about character sets. Assume nothing about |
506 | numerical values (C<ord>, C<chr>) of characters. Do not | |
322422de | 507 | assume that the alphabetic characters are encoded contiguously (in |
b7df3edc | 508 | the numeric sense). Do not assume anything about the ordering of the |
322422de | 509 | characters. The lowercase letters may come before or after the |
b7df3edc GS |
510 | uppercase letters; the lowercase and uppercase may be interlaced so |
511 | that both `a' and `A' come before `b'; the accented and other | |
322422de | 512 | international characters may be interlaced so that E<auml> comes |
b7df3edc | 513 | before `b'. |
322422de GS |
514 | |
515 | =head2 Internationalisation | |
516 | ||
b7df3edc GS |
517 | If you may assume POSIX (a rather large assumption), you may read |
518 | more about the POSIX locale system from L<perllocale>. The locale | |
519 | system at least attempts to make things a little bit more portable, | |
520 | or at least more convenient and native-friendly for non-English | |
521 | users. The system affects character sets and encoding, and date | |
522 | and time formatting--amongst other things. | |
e41182b5 GS |
523 | |
524 | =head2 System Resources | |
525 | ||
0a47030a GS |
526 | If your code is destined for systems with severely constrained (or |
527 | missing!) virtual memory systems then you want to be I<especially> mindful | |
528 | of avoiding wasteful constructs such as: | |
e41182b5 GS |
529 | |
530 | # NOTE: this is no longer "bad" in perl5.005 | |
531 | for (0..10000000) {} # bad | |
532 | for (my $x = 0; $x <= 10000000; ++$x) {} # good | |
533 | ||
534 | @lines = <VERY_LARGE_FILE>; # bad | |
535 | ||
536 | while (<FILE>) {$file .= $_} # sometimes bad | |
0a47030a | 537 | $file = join('', <FILE>); # better |
e41182b5 | 538 | |
b7df3edc GS |
539 | The last two constructs may appear unintuitive to most people. The |
540 | first repeatedly grows a string, whereas the second allocates a | |
541 | large chunk of memory in one go. On some systems, the second is | |
542 | more efficient that the first. | |
0a47030a | 543 | |
e41182b5 GS |
544 | =head2 Security |
545 | ||
b7df3edc GS |
546 | Most multi-user platforms provide basic levels of security, usually |
547 | implemented at the filesystem level. Some, however, do | |
a1667ba3 | 548 | not-- unfortunately. Thus the notion of user id, or "home" directory, |
b7df3edc GS |
549 | or even the state of being logged-in, may be unrecognizable on many |
550 | platforms. If you write programs that are security-conscious, it | |
551 | is usually best to know what type of system you will be running | |
552 | under so that you can write code explicitly for that platform (or | |
553 | class of platforms). | |
0a47030a | 554 | |
a1667ba3 JH |
555 | Don't assume the UNIX filesystem access semantics: the operating |
556 | system or the filesystem may be using some ACL systems, which are | |
557 | richer languages than the usual rwx. Even if the rwx exist, | |
558 | their semantics might be different. | |
559 | ||
560 | (From security viewpoint testing for permissions before attempting to | |
561 | do something is silly anyway: if one tries this, there is potential | |
562 | for race conditions-- someone or something might change the | |
563 | permissions between the permissions check and the actual operation. | |
564 | Just try the operation.) | |
565 | ||
566 | Don't assume the UNIX user and group semantics: especially, don't | |
2edcc0d9 | 567 | expect the C<< $< >> and C<< $> >> (or the C<$(> and C<$)>) to work |
a1667ba3 JH |
568 | for switching identities (or memberships). |
569 | ||
570 | Don't assume set-uid and set-gid semantics. (And even if you do, | |
571 | think twice: set-uid and set-gid are a known can of security worms.) | |
572 | ||
e41182b5 GS |
573 | =head2 Style |
574 | ||
575 | For those times when it is necessary to have platform-specific code, | |
576 | consider keeping the platform-specific code in one place, making porting | |
6ab3f9cb | 577 | to other platforms easier. Use the Config module and the special |
0a47030a GS |
578 | variable C<$^O> to differentiate platforms, as described in |
579 | L<"PLATFORMS">. | |
e41182b5 | 580 | |
b7df3edc GS |
581 | Be careful in the tests you supply with your module or programs. |
582 | Module code may be fully portable, but its tests might not be. This | |
583 | often happens when tests spawn off other processes or call external | |
584 | programs to aid in the testing, or when (as noted above) the tests | |
585 | assume certain things about the filesystem and paths. Be careful | |
586 | not to depend on a specific output style for errors, such as when | |
d1be9408 | 587 | checking C<$!> after a system call. Some platforms expect a certain |
b7df3edc GS |
588 | output format, and perl on those platforms may have been adjusted |
589 | accordingly. Most specifically, don't anchor a regex when testing | |
590 | an error value. | |
e41182b5 | 591 | |
0a47030a | 592 | =head1 CPAN Testers |
e41182b5 | 593 | |
0a47030a GS |
594 | Modules uploaded to CPAN are tested by a variety of volunteers on |
595 | different platforms. These CPAN testers are notified by mail of each | |
e41182b5 | 596 | new upload, and reply to the list with PASS, FAIL, NA (not applicable to |
0a47030a | 597 | this platform), or UNKNOWN (unknown), along with any relevant notations. |
e41182b5 GS |
598 | |
599 | The purpose of the testing is twofold: one, to help developers fix any | |
0a47030a | 600 | problems in their code that crop up because of lack of testing on other |
b7df3edc | 601 | platforms; two, to provide users with information about whether |
0a47030a | 602 | a given module works on a given platform. |
e41182b5 GS |
603 | |
604 | =over 4 | |
605 | ||
606 | =item Mailing list: cpan-testers@perl.org | |
607 | ||
c997b287 | 608 | =item Testing results: http://testers.cpan.org/ |
e41182b5 GS |
609 | |
610 | =back | |
611 | ||
e41182b5 GS |
612 | =head1 PLATFORMS |
613 | ||
614 | As of version 5.002, Perl is built with a C<$^O> variable that | |
615 | indicates the operating system it was built on. This was implemented | |
b7df3edc GS |
616 | to help speed up code that would otherwise have to C<use Config> |
617 | and use the value of C<$Config{osname}>. Of course, to get more | |
e41182b5 GS |
618 | detailed information about the system, looking into C<%Config> is |
619 | certainly recommended. | |
620 | ||
b7df3edc GS |
621 | C<%Config> cannot always be trusted, however, because it was built |
622 | at compile time. If perl was built in one place, then transferred | |
623 | elsewhere, some values may be wrong. The values may even have been | |
624 | edited after the fact. | |
6ab3f9cb | 625 | |
e41182b5 GS |
626 | =head2 Unix |
627 | ||
628 | Perl works on a bewildering variety of Unix and Unix-like platforms (see | |
629 | e.g. most of the files in the F<hints/> directory in the source code kit). | |
630 | On most of these systems, the value of C<$^O> (hence C<$Config{'osname'}>, | |
d1e3b762 GS |
631 | too) is determined either by lowercasing and stripping punctuation from the |
632 | first field of the string returned by typing C<uname -a> (or a similar command) | |
633 | at the shell prompt or by testing the file system for the presence of | |
634 | uniquely named files such as a kernel or header file. Here, for example, | |
635 | are a few of the more popular Unix flavors: | |
e41182b5 | 636 | |
b7df3edc | 637 | uname $^O $Config{'archname'} |
6ab3f9cb | 638 | -------------------------------------------- |
b7df3edc | 639 | AIX aix aix |
6ab3f9cb GS |
640 | BSD/OS bsdos i386-bsdos |
641 | dgux dgux AViiON-dgux | |
642 | DYNIX/ptx dynixptx i386-dynixptx | |
b7df3edc | 643 | FreeBSD freebsd freebsd-i386 |
d1e3b762 | 644 | Linux linux arm-linux |
b7df3edc | 645 | Linux linux i386-linux |
6ab3f9cb GS |
646 | Linux linux i586-linux |
647 | Linux linux ppc-linux | |
b7df3edc GS |
648 | HP-UX hpux PA-RISC1.1 |
649 | IRIX irix irix | |
b787fad4 | 650 | Mac OS X darwin darwin |
d1e3b762 GS |
651 | MachTen PPC machten powerpc-machten |
652 | NeXT 3 next next-fat | |
653 | NeXT 4 next OPENSTEP-Mach | |
6ab3f9cb | 654 | openbsd openbsd i386-openbsd |
b7df3edc | 655 | OSF1 dec_osf alpha-dec_osf |
6ab3f9cb GS |
656 | reliantunix-n svr4 RM400-svr4 |
657 | SCO_SV sco_sv i386-sco_sv | |
658 | SINIX-N svr4 RM400-svr4 | |
659 | sn4609 unicos CRAY_C90-unicos | |
660 | sn6521 unicosmk t3e-unicosmk | |
661 | sn9617 unicos CRAY_J90-unicos | |
b7df3edc GS |
662 | SunOS solaris sun4-solaris |
663 | SunOS solaris i86pc-solaris | |
664 | SunOS4 sunos sun4-sunos | |
e41182b5 | 665 | |
b7df3edc GS |
666 | Because the value of C<$Config{archname}> may depend on the |
667 | hardware architecture, it can vary more than the value of C<$^O>. | |
6ab3f9cb | 668 | |
e41182b5 GS |
669 | =head2 DOS and Derivatives |
670 | ||
b7df3edc | 671 | Perl has long been ported to Intel-style microcomputers running under |
e41182b5 GS |
672 | systems like PC-DOS, MS-DOS, OS/2, and most Windows platforms you can |
673 | bring yourself to mention (except for Windows CE, if you count that). | |
b7df3edc | 674 | Users familiar with I<COMMAND.COM> or I<CMD.EXE> style shells should |
e41182b5 GS |
675 | be aware that each of these file specifications may have subtle |
676 | differences: | |
677 | ||
678 | $filespec0 = "c:/foo/bar/file.txt"; | |
679 | $filespec1 = "c:\\foo\\bar\\file.txt"; | |
680 | $filespec2 = 'c:\foo\bar\file.txt'; | |
681 | $filespec3 = 'c:\\foo\\bar\\file.txt'; | |
682 | ||
b7df3edc GS |
683 | System calls accept either C</> or C<\> as the path separator. |
684 | However, many command-line utilities of DOS vintage treat C</> as | |
685 | the option prefix, so may get confused by filenames containing C</>. | |
686 | Aside from calling any external programs, C</> will work just fine, | |
687 | and probably better, as it is more consistent with popular usage, | |
688 | and avoids the problem of remembering what to backwhack and what | |
689 | not to. | |
e41182b5 | 690 | |
b7df3edc GS |
691 | The DOS FAT filesystem can accommodate only "8.3" style filenames. Under |
692 | the "case-insensitive, but case-preserving" HPFS (OS/2) and NTFS (NT) | |
0a47030a | 693 | filesystems you may have to be careful about case returned with functions |
e41182b5 GS |
694 | like C<readdir> or used with functions like C<open> or C<opendir>. |
695 | ||
b7df3edc GS |
696 | DOS also treats several filenames as special, such as AUX, PRN, |
697 | NUL, CON, COM1, LPT1, LPT2, etc. Unfortunately, sometimes these | |
698 | filenames won't even work if you include an explicit directory | |
699 | prefix. It is best to avoid such filenames, if you want your code | |
700 | to be portable to DOS and its derivatives. It's hard to know what | |
701 | these all are, unfortunately. | |
e41182b5 GS |
702 | |
703 | Users of these operating systems may also wish to make use of | |
b7df3edc | 704 | scripts such as I<pl2bat.bat> or I<pl2cmd> to |
e41182b5 GS |
705 | put wrappers around your scripts. |
706 | ||
707 | Newline (C<\n>) is translated as C<\015\012> by STDIO when reading from | |
6ab3f9cb GS |
708 | and writing to files (see L<"Newlines">). C<binmode(FILEHANDLE)> |
709 | will keep C<\n> translated as C<\012> for that filehandle. Since it is a | |
710 | no-op on other systems, C<binmode> should be used for cross-platform code | |
b7df3edc GS |
711 | that deals with binary data. That's assuming you realize in advance |
712 | that your data is in binary. General-purpose programs should | |
713 | often assume nothing about their data. | |
e41182b5 | 714 | |
b7df3edc | 715 | The C<$^O> variable and the C<$Config{archname}> values for various |
e41182b5 GS |
716 | DOSish perls are as follows: |
717 | ||
67ac489e MS |
718 | OS $^O $Config{archname} ID Version |
719 | -------------------------------------------------------- | |
720 | MS-DOS dos ? | |
721 | PC-DOS dos ? | |
722 | OS/2 os2 ? | |
723 | Windows 3.1 ? ? 0 3 01 | |
724 | Windows 95 MSWin32 MSWin32-x86 1 4 00 | |
725 | Windows 98 MSWin32 MSWin32-x86 1 4 10 | |
726 | Windows ME MSWin32 MSWin32-x86 1 ? | |
727 | Windows NT MSWin32 MSWin32-x86 2 4 xx | |
728 | Windows NT MSWin32 MSWin32-ALPHA 2 4 xx | |
729 | Windows NT MSWin32 MSWin32-ppc 2 4 xx | |
730 | Windows 2000 MSWin32 MSWin32-x86 2 5 xx | |
731 | Windows XP MSWin32 MSWin32-x86 2 ? | |
732 | Windows CE MSWin32 ? 3 | |
733 | Cygwin cygwin ? | |
e41182b5 | 734 | |
34aaaa84 PP |
735 | The various MSWin32 Perl's can distinguish the OS they are running on |
736 | via the value of the fifth element of the list returned from | |
737 | Win32::GetOSVersion(). For example: | |
738 | ||
739 | if ($^O eq 'MSWin32') { | |
740 | my @os_version_info = Win32::GetOSVersion(); | |
741 | print +('3.1','95','NT')[$os_version_info[4]],"\n"; | |
742 | } | |
743 | ||
e41182b5 GS |
744 | Also see: |
745 | ||
746 | =over 4 | |
747 | ||
c997b287 | 748 | =item * |
e41182b5 | 749 | |
c997b287 GS |
750 | The djgpp environment for DOS, http://www.delorie.com/djgpp/ |
751 | and L<perldos>. | |
e41182b5 | 752 | |
c997b287 | 753 | =item * |
e41182b5 | 754 | |
c997b287 GS |
755 | The EMX environment for DOS, OS/2, etc. emx@iaehv.nl, |
756 | http://www.leo.org/pub/comp/os/os2/leo/gnu/emx+gcc/index.html or | |
757 | ftp://hobbes.nmsu.edu/pub/os2/dev/emx. Also L<perlos2>. | |
e41182b5 | 758 | |
c997b287 | 759 | =item * |
d1e3b762 | 760 | |
c997b287 GS |
761 | Build instructions for Win32 in L<perlwin32>, or under the Cygnus environment |
762 | in L<perlcygwin>. | |
763 | ||
764 | =item * | |
765 | ||
766 | The C<Win32::*> modules in L<Win32>. | |
767 | ||
768 | =item * | |
769 | ||
770 | The ActiveState Pages, http://www.activestate.com/ | |
771 | ||
772 | =item * | |
773 | ||
774 | The Cygwin environment for Win32; F<README.cygwin> (installed | |
47dafe4d | 775 | as L<perlcygwin>), http://www.cygwin.com/ |
c997b287 GS |
776 | |
777 | =item * | |
778 | ||
779 | The U/WIN environment for Win32, | |
cea6626f | 780 | http://www.research.att.com/sw/tools/uwin/ |
c997b287 | 781 | |
cea6626f | 782 | =item * |
d1e3b762 | 783 | |
cea6626f | 784 | Build instructions for OS/2, L<perlos2> |
d1e3b762 | 785 | |
e41182b5 GS |
786 | =back |
787 | ||
dd9f0070 | 788 | =head2 S<Mac OS> |
e41182b5 GS |
789 | |
790 | Any module requiring XS compilation is right out for most people, because | |
791 | MacPerl is built using non-free (and non-cheap!) compilers. Some XS | |
792 | modules that can work with MacPerl are built and distributed in binary | |
6ab3f9cb | 793 | form on CPAN. |
e41182b5 GS |
794 | |
795 | Directories are specified as: | |
796 | ||
797 | volume:folder:file for absolute pathnames | |
798 | volume:folder: for absolute pathnames | |
799 | :folder:file for relative pathnames | |
800 | :folder: for relative pathnames | |
801 | :file for relative pathnames | |
802 | file for relative pathnames | |
803 | ||
b7df3edc | 804 | Files are stored in the directory in alphabetical order. Filenames are |
6ab3f9cb | 805 | limited to 31 characters, and may include any character except for |
b7df3edc | 806 | null and C<:>, which is reserved as the path separator. |
e41182b5 | 807 | |
0a47030a | 808 | Instead of C<flock>, see C<FSpSetFLock> and C<FSpRstFLock> in the |
6ab3f9cb | 809 | Mac::Files module, or C<chmod(0444, ...)> and C<chmod(0666, ...)>. |
e41182b5 GS |
810 | |
811 | In the MacPerl application, you can't run a program from the command line; | |
812 | programs that expect C<@ARGV> to be populated can be edited with something | |
813 | like the following, which brings up a dialog box asking for the command | |
814 | line arguments. | |
815 | ||
816 | if (!@ARGV) { | |
817 | @ARGV = split /\s+/, MacPerl::Ask('Arguments?'); | |
818 | } | |
819 | ||
b7df3edc | 820 | A MacPerl script saved as a "droplet" will populate C<@ARGV> with the full |
e41182b5 GS |
821 | pathnames of the files dropped onto the script. |
822 | ||
b7df3edc GS |
823 | Mac users can run programs under a type of command line interface |
824 | under MPW (Macintosh Programmer's Workshop, a free development | |
825 | environment from Apple). MacPerl was first introduced as an MPW | |
826 | tool, and MPW can be used like a shell: | |
e41182b5 GS |
827 | |
828 | perl myscript.plx some arguments | |
829 | ||
830 | ToolServer is another app from Apple that provides access to MPW tools | |
0a47030a | 831 | from MPW and the MacPerl app, which allows MacPerl programs to use |
e41182b5 GS |
832 | C<system>, backticks, and piped C<open>. |
833 | ||
834 | "S<Mac OS>" is the proper name for the operating system, but the value | |
835 | in C<$^O> is "MacOS". To determine architecture, version, or whether | |
836 | the application or MPW tool version is running, check: | |
837 | ||
838 | $is_app = $MacPerl::Version =~ /App/; | |
839 | $is_tool = $MacPerl::Version =~ /MPW/; | |
840 | ($version) = $MacPerl::Version =~ /^(\S+)/; | |
841 | $is_ppc = $MacPerl::Architecture eq 'MacPPC'; | |
842 | $is_68k = $MacPerl::Architecture eq 'Mac68K'; | |
843 | ||
b787fad4 JH |
844 | S<Mac OS X>, based on NeXT's OpenStep OS, runs MacPerl natively, under the |
845 | "Classic" environment. There is no "Carbon" version of MacPerl to run | |
846 | under the primary Mac OS X environment. S<Mac OS X> and its Open Source | |
847 | version, Darwin, both run Unix perl natively. | |
6ab3f9cb | 848 | |
e41182b5 GS |
849 | Also see: |
850 | ||
851 | =over 4 | |
852 | ||
c997b287 GS |
853 | =item * |
854 | ||
862b5365 | 855 | MacPerl Development, http://dev.macperl.org/ . |
c997b287 GS |
856 | |
857 | =item * | |
858 | ||
862b5365 | 859 | The MacPerl Pages, http://www.macperl.com/ . |
e41182b5 | 860 | |
c997b287 | 861 | =item * |
6ab3f9cb | 862 | |
862b5365 | 863 | The MacPerl mailing lists, http://lists.perl.org/ . |
e41182b5 GS |
864 | |
865 | =back | |
866 | ||
e41182b5 GS |
867 | =head2 VMS |
868 | ||
c997b287 | 869 | Perl on VMS is discussed in L<perlvms> in the perl distribution. |
b7df3edc | 870 | Perl on VMS can accept either VMS- or Unix-style file |
e41182b5 GS |
871 | specifications as in either of the following: |
872 | ||
873 | $ perl -ne "print if /perl_setup/i" SYS$LOGIN:LOGIN.COM | |
874 | $ perl -ne "print if /perl_setup/i" /sys$login/login.com | |
875 | ||
876 | but not a mixture of both as in: | |
877 | ||
878 | $ perl -ne "print if /perl_setup/i" sys$login:/login.com | |
879 | Can't open sys$login:/login.com: file specification syntax error | |
880 | ||
881 | Interacting with Perl from the Digital Command Language (DCL) shell | |
882 | often requires a different set of quotation marks than Unix shells do. | |
883 | For example: | |
884 | ||
885 | $ perl -e "print ""Hello, world.\n""" | |
886 | Hello, world. | |
887 | ||
b7df3edc | 888 | There are several ways to wrap your perl scripts in DCL F<.COM> files, if |
e41182b5 GS |
889 | you are so inclined. For example: |
890 | ||
891 | $ write sys$output "Hello from DCL!" | |
892 | $ if p1 .eqs. "" | |
893 | $ then perl -x 'f$environment("PROCEDURE") | |
894 | $ else perl -x - 'p1 'p2 'p3 'p4 'p5 'p6 'p7 'p8 | |
895 | $ deck/dollars="__END__" | |
896 | #!/usr/bin/perl | |
897 | ||
898 | print "Hello from Perl!\n"; | |
899 | ||
900 | __END__ | |
901 | $ endif | |
902 | ||
903 | Do take care with C<$ ASSIGN/nolog/user SYS$COMMAND: SYS$INPUT> if your | |
c47ff5f1 | 904 | perl-in-DCL script expects to do things like C<< $read = <STDIN>; >>. |
e41182b5 GS |
905 | |
906 | Filenames are in the format "name.extension;version". The maximum | |
907 | length for filenames is 39 characters, and the maximum length for | |
908 | extensions is also 39 characters. Version is a number from 1 to | |
909 | 32767. Valid characters are C</[A-Z0-9$_-]/>. | |
910 | ||
b7df3edc | 911 | VMS's RMS filesystem is case-insensitive and does not preserve case. |
e41182b5 | 912 | C<readdir> returns lowercased filenames, but specifying a file for |
b7df3edc | 913 | opening remains case-insensitive. Files without extensions have a |
e41182b5 | 914 | trailing period on them, so doing a C<readdir> with a file named F<A.;5> |
0a47030a GS |
915 | will return F<a.> (though that file could be opened with |
916 | C<open(FH, 'A')>). | |
e41182b5 | 917 | |
f34d0673 | 918 | RMS had an eight level limit on directory depths from any rooted logical |
dd9f0070 CN |
919 | (allowing 16 levels overall) prior to VMS 7.2. Hence |
920 | C<PERL_ROOT:[LIB.2.3.4.5.6.7.8]> is a valid directory specification but | |
921 | C<PERL_ROOT:[LIB.2.3.4.5.6.7.8.9]> is not. F<Makefile.PL> authors might | |
922 | have to take this into account, but at least they can refer to the former | |
f34d0673 | 923 | as C</PERL_ROOT/lib/2/3/4/5/6/7/8/>. |
e41182b5 | 924 | |
6ab3f9cb | 925 | The VMS::Filespec module, which gets installed as part of the build |
0a47030a GS |
926 | process on VMS, is a pure Perl module that can easily be installed on |
927 | non-VMS platforms and can be helpful for conversions to and from RMS | |
928 | native formats. | |
e41182b5 | 929 | |
5e12dbfa PP |
930 | What C<\n> represents depends on the type of file opened. It usually |
931 | represents C<\012> but it could also be C<\015>, C<\012>, C<\015\012>, | |
932 | C<\000>, C<\040>, or nothing depending on the file organiztion and | |
933 | record format. The VMS::Stdio module provides access to the | |
934 | special fopen() requirements of files with unusual attributes on VMS. | |
e41182b5 GS |
935 | |
936 | TCP/IP stacks are optional on VMS, so socket routines might not be | |
937 | implemented. UDP sockets may not be supported. | |
938 | ||
939 | The value of C<$^O> on OpenVMS is "VMS". To determine the architecture | |
940 | that you are running on without resorting to loading all of C<%Config> | |
941 | you can examine the content of the C<@INC> array like so: | |
942 | ||
943 | if (grep(/VMS_AXP/, @INC)) { | |
944 | print "I'm on Alpha!\n"; | |
6ab3f9cb | 945 | |
e41182b5 GS |
946 | } elsif (grep(/VMS_VAX/, @INC)) { |
947 | print "I'm on VAX!\n"; | |
6ab3f9cb | 948 | |
e41182b5 GS |
949 | } else { |
950 | print "I'm not so sure about where $^O is...\n"; | |
951 | } | |
952 | ||
b7df3edc GS |
953 | On VMS, perl determines the UTC offset from the C<SYS$TIMEZONE_DIFFERENTIAL> |
954 | logical name. Although the VMS epoch began at 17-NOV-1858 00:00:00.00, | |
6ab3f9cb | 955 | calls to C<localtime> are adjusted to count offsets from |
b7df3edc | 956 | 01-JAN-1970 00:00:00.00, just like Unix. |
6ab3f9cb | 957 | |
e41182b5 GS |
958 | Also see: |
959 | ||
960 | =over 4 | |
961 | ||
c997b287 GS |
962 | =item * |
963 | ||
964 | F<README.vms> (installed as L<README_vms>), L<perlvms> | |
965 | ||
966 | =item * | |
967 | ||
968 | vmsperl list, majordomo@perl.org | |
e41182b5 | 969 | |
c997b287 | 970 | (Put the words C<subscribe vmsperl> in message body.) |
e41182b5 | 971 | |
c997b287 | 972 | =item * |
e41182b5 | 973 | |
c997b287 | 974 | vmsperl on the web, http://www.sidhe.org/vmsperl/index.html |
e41182b5 GS |
975 | |
976 | =back | |
977 | ||
495c5fdc PG |
978 | =head2 VOS |
979 | ||
9a997319 JH |
980 | Perl on VOS is discussed in F<README.vos> in the perl distribution |
981 | (installed as L<perlvos>). Perl on VOS can accept either VOS- or | |
982 | Unix-style file specifications as in either of the following: | |
495c5fdc PG |
983 | |
984 | $ perl -ne "print if /perl_setup/i" >system>notices | |
985 | $ perl -ne "print if /perl_setup/i" /system/notices | |
986 | ||
987 | or even a mixture of both as in: | |
988 | ||
989 | $ perl -ne "print if /perl_setup/i" >system/notices | |
990 | ||
b7df3edc | 991 | Even though VOS allows the slash character to appear in object |
495c5fdc PG |
992 | names, because the VOS port of Perl interprets it as a pathname |
993 | delimiting character, VOS files, directories, or links whose names | |
994 | contain a slash character cannot be processed. Such files must be | |
a3dfe201 GS |
995 | renamed before they can be processed by Perl. Note that VOS limits |
996 | file names to 32 or fewer characters. | |
495c5fdc | 997 | |
5b8c1387 JH |
998 | See F<README.vos> for restrictions that apply when Perl is built |
999 | with the alpha version of VOS POSIX.1 support. | |
1000 | ||
1001 | Perl on VOS is built without any extensions and does not support | |
1002 | dynamic loading. | |
495c5fdc PG |
1003 | |
1004 | The value of C<$^O> on VOS is "VOS". To determine the architecture that | |
1005 | you are running on without resorting to loading all of C<%Config> you | |
c997b287 | 1006 | can examine the content of the @INC array like so: |
495c5fdc | 1007 | |
24e8e380 | 1008 | if ($^O =~ /VOS/) { |
495c5fdc PG |
1009 | print "I'm on a Stratus box!\n"; |
1010 | } else { | |
1011 | print "I'm not on a Stratus box!\n"; | |
1012 | die; | |
1013 | } | |
1014 | ||
1015 | if (grep(/860/, @INC)) { | |
1016 | print "This box is a Stratus XA/R!\n"; | |
6ab3f9cb | 1017 | |
495c5fdc | 1018 | } elsif (grep(/7100/, @INC)) { |
24e8e380 | 1019 | print "This box is a Stratus HP 7100 or 8xxx!\n"; |
6ab3f9cb | 1020 | |
495c5fdc | 1021 | } elsif (grep(/8000/, @INC)) { |
24e8e380 | 1022 | print "This box is a Stratus HP 8xxx!\n"; |
6ab3f9cb | 1023 | |
495c5fdc | 1024 | } else { |
24e8e380 | 1025 | print "This box is a Stratus 68K!\n"; |
495c5fdc PG |
1026 | } |
1027 | ||
1028 | Also see: | |
1029 | ||
1030 | =over 4 | |
1031 | ||
c997b287 | 1032 | =item * |
495c5fdc | 1033 | |
c997b287 GS |
1034 | F<README.vos> |
1035 | ||
1036 | =item * | |
1037 | ||
1038 | The VOS mailing list. | |
495c5fdc PG |
1039 | |
1040 | There is no specific mailing list for Perl on VOS. You can post | |
1041 | comments to the comp.sys.stratus newsgroup, or subscribe to the general | |
1042 | Stratus mailing list. Send a letter with "Subscribe Info-Stratus" in | |
1043 | the message body to majordomo@list.stratagy.com. | |
1044 | ||
c997b287 GS |
1045 | =item * |
1046 | ||
1047 | VOS Perl on the web at http://ftp.stratus.com/pub/vos/vos.html | |
495c5fdc PG |
1048 | |
1049 | =back | |
1050 | ||
e41182b5 GS |
1051 | =head2 EBCDIC Platforms |
1052 | ||
1053 | Recent versions of Perl have been ported to platforms such as OS/400 on | |
d1e3b762 GS |
1054 | AS/400 minicomputers as well as OS/390, VM/ESA, and BS2000 for S/390 |
1055 | Mainframes. Such computers use EBCDIC character sets internally (usually | |
0cc436d0 GS |
1056 | Character Code Set ID 0037 for OS/400 and either 1047 or POSIX-BC for S/390 |
1057 | systems). On the mainframe perl currently works under the "Unix system | |
1058 | services for OS/390" (formerly known as OpenEdition), VM/ESA OpenEdition, or | |
1059 | the BS200 POSIX-BC system (BS2000 is supported in perl 5.6 and greater). | |
c997b287 | 1060 | See L<perlos390> for details. |
e41182b5 | 1061 | |
7c5ffed3 JH |
1062 | As of R2.5 of USS for OS/390 and Version 2.3 of VM/ESA these Unix |
1063 | sub-systems do not support the C<#!> shebang trick for script invocation. | |
1064 | Hence, on OS/390 and VM/ESA perl scripts can be executed with a header | |
1065 | similar to the following simple script: | |
e41182b5 GS |
1066 | |
1067 | : # use perl | |
1068 | eval 'exec /usr/local/bin/perl -S $0 ${1+"$@"}' | |
1069 | if 0; | |
1070 | #!/usr/local/bin/perl # just a comment really | |
1071 | ||
1072 | print "Hello from perl!\n"; | |
1073 | ||
d1e3b762 GS |
1074 | OS/390 will support the C<#!> shebang trick in release 2.8 and beyond. |
1075 | Calls to C<system> and backticks can use POSIX shell syntax on all | |
1076 | S/390 systems. | |
1077 | ||
b7df3edc | 1078 | On the AS/400, if PERL5 is in your library list, you may need |
6ab3f9cb GS |
1079 | to wrap your perl scripts in a CL procedure to invoke them like so: |
1080 | ||
1081 | BEGIN | |
1082 | CALL PGM(PERL5/PERL) PARM('/QOpenSys/hello.pl') | |
1083 | ENDPGM | |
1084 | ||
1085 | This will invoke the perl script F<hello.pl> in the root of the | |
1086 | QOpenSys file system. On the AS/400 calls to C<system> or backticks | |
1087 | must use CL syntax. | |
1088 | ||
e41182b5 | 1089 | On these platforms, bear in mind that the EBCDIC character set may have |
0a47030a GS |
1090 | an effect on what happens with some perl functions (such as C<chr>, |
1091 | C<pack>, C<print>, C<printf>, C<ord>, C<sort>, C<sprintf>, C<unpack>), as | |
1092 | well as bit-fiddling with ASCII constants using operators like C<^>, C<&> | |
1093 | and C<|>, not to mention dealing with socket interfaces to ASCII computers | |
6ab3f9cb | 1094 | (see L<"Newlines">). |
e41182b5 | 1095 | |
b7df3edc GS |
1096 | Fortunately, most web servers for the mainframe will correctly |
1097 | translate the C<\n> in the following statement to its ASCII equivalent | |
1098 | (C<\r> is the same under both Unix and OS/390 & VM/ESA): | |
e41182b5 GS |
1099 | |
1100 | print "Content-type: text/html\r\n\r\n"; | |
1101 | ||
d1e3b762 | 1102 | The values of C<$^O> on some of these platforms includes: |
e41182b5 | 1103 | |
d1e3b762 GS |
1104 | uname $^O $Config{'archname'} |
1105 | -------------------------------------------- | |
1106 | OS/390 os390 os390 | |
1107 | OS400 os400 os400 | |
1108 | POSIX-BC posix-bc BS2000-posix-bc | |
1109 | VM/ESA vmesa vmesa | |
3c075c7d | 1110 | |
e41182b5 GS |
1111 | Some simple tricks for determining if you are running on an EBCDIC |
1112 | platform could include any of the following (perhaps all): | |
1113 | ||
1114 | if ("\t" eq "\05") { print "EBCDIC may be spoken here!\n"; } | |
1115 | ||
1116 | if (ord('A') == 193) { print "EBCDIC may be spoken here!\n"; } | |
1117 | ||
1118 | if (chr(169) eq 'z') { print "EBCDIC may be spoken here!\n"; } | |
1119 | ||
b7df3edc | 1120 | One thing you may not want to rely on is the EBCDIC encoding |
0a47030a GS |
1121 | of punctuation characters since these may differ from code page to code |
1122 | page (and once your module or script is rumoured to work with EBCDIC, | |
1123 | folks will want it to work with all EBCDIC character sets). | |
e41182b5 GS |
1124 | |
1125 | Also see: | |
1126 | ||
1127 | =over 4 | |
1128 | ||
c997b287 GS |
1129 | =item * |
1130 | ||
1131 | * | |
d1e3b762 | 1132 | |
dc5c060f | 1133 | L<perlos390>, F<README.os390>, F<perlbs2000>, F<README.vmesa>, |
bb462878 | 1134 | L<perlebcdic>. |
c997b287 GS |
1135 | |
1136 | =item * | |
e41182b5 GS |
1137 | |
1138 | The perl-mvs@perl.org list is for discussion of porting issues as well as | |
1139 | general usage issues for all EBCDIC Perls. Send a message body of | |
1140 | "subscribe perl-mvs" to majordomo@perl.org. | |
1141 | ||
c997b287 GS |
1142 | =item * |
1143 | ||
1144 | AS/400 Perl information at | |
b1866b2d | 1145 | http://as400.rochester.ibm.com/ |
d1e3b762 | 1146 | as well as on CPAN in the F<ports/> directory. |
e41182b5 GS |
1147 | |
1148 | =back | |
1149 | ||
b8099c3d CN |
1150 | =head2 Acorn RISC OS |
1151 | ||
b7df3edc GS |
1152 | Because Acorns use ASCII with newlines (C<\n>) in text files as C<\012> like |
1153 | Unix, and because Unix filename emulation is turned on by default, | |
1154 | most simple scripts will probably work "out of the box". The native | |
6ab3f9cb | 1155 | filesystem is modular, and individual filesystems are free to be |
0a47030a | 1156 | case-sensitive or insensitive, and are usually case-preserving. Some |
b7df3edc | 1157 | native filesystems have name length limits, which file and directory |
6ab3f9cb GS |
1158 | names are silently truncated to fit. Scripts should be aware that the |
1159 | standard filesystem currently has a name length limit of B<10> | |
1160 | characters, with up to 77 items in a directory, but other filesystems | |
0a47030a | 1161 | may not impose such limitations. |
b8099c3d CN |
1162 | |
1163 | Native filenames are of the form | |
1164 | ||
6ab3f9cb | 1165 | Filesystem#Special_Field::DiskName.$.Directory.Directory.File |
dd9f0070 | 1166 | |
b8099c3d CN |
1167 | where |
1168 | ||
1169 | Special_Field is not usually present, but may contain . and $ . | |
1170 | Filesystem =~ m|[A-Za-z0-9_]| | |
1171 | DsicName =~ m|[A-Za-z0-9_/]| | |
1172 | $ represents the root directory | |
1173 | . is the path separator | |
1174 | @ is the current directory (per filesystem but machine global) | |
1175 | ^ is the parent directory | |
1176 | Directory and File =~ m|[^\0- "\.\$\%\&:\@\\^\|\177]+| | |
1177 | ||
1178 | The default filename translation is roughly C<tr|/.|./|;> | |
1179 | ||
6ab3f9cb | 1180 | Note that C<"ADFS::HardDisk.$.File" ne 'ADFS::HardDisk.$.File'> and that |
0a47030a GS |
1181 | the second stage of C<$> interpolation in regular expressions will fall |
1182 | foul of the C<$.> if scripts are not careful. | |
1183 | ||
1184 | Logical paths specified by system variables containing comma-separated | |
b7df3edc | 1185 | search lists are also allowed; hence C<System:Modules> is a valid |
0a47030a | 1186 | filename, and the filesystem will prefix C<Modules> with each section of |
6ab3f9cb | 1187 | C<System$Path> until a name is made that points to an object on disk. |
b7df3edc | 1188 | Writing to a new file C<System:Modules> would be allowed only if |
0a47030a GS |
1189 | C<System$Path> contains a single item list. The filesystem will also |
1190 | expand system variables in filenames if enclosed in angle brackets, so | |
c47ff5f1 | 1191 | C<< <System$Dir>.Modules >> would look for the file |
0a47030a | 1192 | S<C<$ENV{'System$Dir'} . 'Modules'>>. The obvious implication of this is |
c47ff5f1 | 1193 | that B<fully qualified filenames can start with C<< <> >>> and should |
0a47030a | 1194 | be protected when C<open> is used for input. |
b8099c3d CN |
1195 | |
1196 | Because C<.> was in use as a directory separator and filenames could not | |
1197 | be assumed to be unique after 10 characters, Acorn implemented the C | |
1198 | compiler to strip the trailing C<.c> C<.h> C<.s> and C<.o> suffix from | |
1199 | filenames specified in source code and store the respective files in | |
b7df3edc | 1200 | subdirectories named after the suffix. Hence files are translated: |
b8099c3d CN |
1201 | |
1202 | foo.h h.foo | |
1203 | C:foo.h C:h.foo (logical path variable) | |
1204 | sys/os.h sys.h.os (C compiler groks Unix-speak) | |
1205 | 10charname.c c.10charname | |
1206 | 10charname.o o.10charname | |
1207 | 11charname_.c c.11charname (assuming filesystem truncates at 10) | |
1208 | ||
1209 | The Unix emulation library's translation of filenames to native assumes | |
b7df3edc GS |
1210 | that this sort of translation is required, and it allows a user-defined list |
1211 | of known suffixes that it will transpose in this fashion. This may | |
1212 | seem transparent, but consider that with these rules C<foo/bar/baz.h> | |
0a47030a GS |
1213 | and C<foo/bar/h/baz> both map to C<foo.bar.h.baz>, and that C<readdir> and |
1214 | C<glob> cannot and do not attempt to emulate the reverse mapping. Other | |
6ab3f9cb | 1215 | C<.>'s in filenames are translated to C</>. |
0a47030a | 1216 | |
b7df3edc | 1217 | As implied above, the environment accessed through C<%ENV> is global, and |
0a47030a | 1218 | the convention is that program specific environment variables are of the |
6ab3f9cb GS |
1219 | form C<Program$Name>. Each filesystem maintains a current directory, |
1220 | and the current filesystem's current directory is the B<global> current | |
b7df3edc GS |
1221 | directory. Consequently, sociable programs don't change the current |
1222 | directory but rely on full pathnames, and programs (and Makefiles) cannot | |
0a47030a GS |
1223 | assume that they can spawn a child process which can change the current |
1224 | directory without affecting its parent (and everyone else for that | |
1225 | matter). | |
1226 | ||
b7df3edc GS |
1227 | Because native operating system filehandles are global and are currently |
1228 | allocated down from 255, with 0 being a reserved value, the Unix emulation | |
0a47030a GS |
1229 | library emulates Unix filehandles. Consequently, you can't rely on |
1230 | passing C<STDIN>, C<STDOUT>, or C<STDERR> to your children. | |
1231 | ||
1232 | The desire of users to express filenames of the form | |
c47ff5f1 | 1233 | C<< <Foo$Dir>.Bar >> on the command line unquoted causes problems, |
0a47030a | 1234 | too: C<``> command output capture has to perform a guessing game. It |
c47ff5f1 | 1235 | assumes that a string C<< <[^<>]+\$[^<>]> >> is a |
0a47030a | 1236 | reference to an environment variable, whereas anything else involving |
c47ff5f1 | 1237 | C<< < >> or C<< > >> is redirection, and generally manages to be 99% |
0a47030a GS |
1238 | right. Of course, the problem remains that scripts cannot rely on any |
1239 | Unix tools being available, or that any tools found have Unix-like command | |
1240 | line arguments. | |
1241 | ||
b7df3edc GS |
1242 | Extensions and XS are, in theory, buildable by anyone using free |
1243 | tools. In practice, many don't, as users of the Acorn platform are | |
1244 | used to binary distributions. MakeMaker does run, but no available | |
1245 | make currently copes with MakeMaker's makefiles; even if and when | |
1246 | this should be fixed, the lack of a Unix-like shell will cause | |
1247 | problems with makefile rules, especially lines of the form C<cd | |
1248 | sdbm && make all>, and anything using quoting. | |
b8099c3d CN |
1249 | |
1250 | "S<RISC OS>" is the proper name for the operating system, but the value | |
1251 | in C<$^O> is "riscos" (because we don't like shouting). | |
1252 | ||
e41182b5 GS |
1253 | =head2 Other perls |
1254 | ||
b7df3edc GS |
1255 | Perl has been ported to many platforms that do not fit into any of |
1256 | the categories listed above. Some, such as AmigaOS, Atari MiNT, | |
1257 | BeOS, HP MPE/iX, QNX, Plan 9, and VOS, have been well-integrated | |
1258 | into the standard Perl source code kit. You may need to see the | |
1259 | F<ports/> directory on CPAN for information, and possibly binaries, | |
1260 | for the likes of: aos, Atari ST, lynxos, riscos, Novell Netware, | |
1261 | Tandem Guardian, I<etc.> (Yes, we know that some of these OSes may | |
1262 | fall under the Unix category, but we are not a standards body.) | |
e41182b5 | 1263 | |
d1e3b762 GS |
1264 | Some approximate operating system names and their C<$^O> values |
1265 | in the "OTHER" category include: | |
1266 | ||
1267 | OS $^O $Config{'archname'} | |
1268 | ------------------------------------------ | |
1269 | Amiga DOS amigaos m68k-amigos | |
1270 | MPE/iX mpeix PA-RISC1.1 | |
1271 | ||
e41182b5 GS |
1272 | See also: |
1273 | ||
1274 | =over 4 | |
1275 | ||
c997b287 GS |
1276 | =item * |
1277 | ||
1278 | Amiga, F<README.amiga> (installed as L<perlamiga>). | |
1279 | ||
1280 | =item * | |
d1e3b762 | 1281 | |
c997b287 GS |
1282 | Atari, F<README.mint> and Guido Flohr's web page |
1283 | http://stud.uni-sb.de/~gufl0000/ | |
e41182b5 | 1284 | |
c997b287 | 1285 | =item * |
d1e3b762 | 1286 | |
c997b287 | 1287 | Be OS, F<README.beos> |
e41182b5 | 1288 | |
c997b287 GS |
1289 | =item * |
1290 | ||
1291 | HP 300 MPE/iX, F<README.mpeix> and Mark Bixby's web page | |
34aaaa84 | 1292 | http://www.bixby.org/mark/perlix.html |
c997b287 GS |
1293 | |
1294 | =item * | |
e41182b5 | 1295 | |
6ab3f9cb | 1296 | A free perl5-based PERL.NLM for Novell Netware is available in |
c997b287 | 1297 | precompiled binary and source code form from http://www.novell.com/ |
6ab3f9cb | 1298 | as well as from CPAN. |
e41182b5 | 1299 | |
13a2d996 | 1300 | =item * |
c997b287 GS |
1301 | |
1302 | Plan 9, F<README.plan9> | |
d1e3b762 | 1303 | |
e41182b5 GS |
1304 | =back |
1305 | ||
e41182b5 GS |
1306 | =head1 FUNCTION IMPLEMENTATIONS |
1307 | ||
b7df3edc GS |
1308 | Listed below are functions that are either completely unimplemented |
1309 | or else have been implemented differently on various platforms. | |
1310 | Following each description will be, in parentheses, a list of | |
1311 | platforms that the description applies to. | |
e41182b5 | 1312 | |
b7df3edc GS |
1313 | The list may well be incomplete, or even wrong in some places. When |
1314 | in doubt, consult the platform-specific README files in the Perl | |
1315 | source distribution, and any other documentation resources accompanying | |
1316 | a given port. | |
e41182b5 | 1317 | |
0a47030a | 1318 | Be aware, moreover, that even among Unix-ish systems there are variations. |
e41182b5 | 1319 | |
b7df3edc GS |
1320 | For many functions, you can also query C<%Config>, exported by |
1321 | default from the Config module. For example, to check whether the | |
1322 | platform has the C<lstat> call, check C<$Config{d_lstat}>. See | |
1323 | L<Config> for a full description of available variables. | |
e41182b5 GS |
1324 | |
1325 | =head2 Alphabetical Listing of Perl Functions | |
1326 | ||
1327 | =over 8 | |
1328 | ||
1329 | =item -X FILEHANDLE | |
1330 | ||
1331 | =item -X EXPR | |
1332 | ||
1333 | =item -X | |
1334 | ||
b7df3edc | 1335 | C<-r>, C<-w>, and C<-x> have a limited meaning only; directories |
e41182b5 | 1336 | and applications are executable, and there are no uid/gid |
b7df3edc | 1337 | considerations. C<-o> is not supported. (S<Mac OS>) |
e41182b5 | 1338 | |
b7df3edc GS |
1339 | C<-r>, C<-w>, C<-x>, and C<-o> tell whether the file is accessible, |
1340 | which may not reflect UIC-based file protections. (VMS) | |
e41182b5 | 1341 | |
b8099c3d CN |
1342 | C<-s> returns the size of the data fork, not the total size of data fork |
1343 | plus resource fork. (S<Mac OS>). | |
1344 | ||
1345 | C<-s> by name on an open file will return the space reserved on disk, | |
1346 | rather than the current extent. C<-s> on an open filehandle returns the | |
b7df3edc | 1347 | current size. (S<RISC OS>) |
b8099c3d | 1348 | |
e41182b5 | 1349 | C<-R>, C<-W>, C<-X>, C<-O> are indistinguishable from C<-r>, C<-w>, |
b8099c3d | 1350 | C<-x>, C<-o>. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 GS |
1351 | |
1352 | C<-b>, C<-c>, C<-k>, C<-g>, C<-p>, C<-u>, C<-A> are not implemented. | |
1353 | (S<Mac OS>) | |
1354 | ||
1355 | C<-g>, C<-k>, C<-l>, C<-p>, C<-u>, C<-A> are not particularly meaningful. | |
b8099c3d | 1356 | (Win32, VMS, S<RISC OS>) |
e41182b5 GS |
1357 | |
1358 | C<-d> is true if passed a device spec without an explicit directory. | |
1359 | (VMS) | |
1360 | ||
1361 | C<-T> and C<-B> are implemented, but might misclassify Mac text files | |
0a47030a | 1362 | with foreign characters; this is the case will all platforms, but may |
b7df3edc | 1363 | affect S<Mac OS> often. (S<Mac OS>) |
e41182b5 GS |
1364 | |
1365 | C<-x> (or C<-X>) determine if a file ends in one of the executable | |
b7df3edc | 1366 | suffixes. C<-S> is meaningless. (Win32) |
e41182b5 | 1367 | |
b8099c3d CN |
1368 | C<-x> (or C<-X>) determine if a file has an executable file type. |
1369 | (S<RISC OS>) | |
1370 | ||
63f87e49 GS |
1371 | =item alarm SECONDS |
1372 | ||
1373 | =item alarm | |
1374 | ||
1375 | Not implemented. (Win32) | |
1376 | ||
e41182b5 GS |
1377 | =item binmode FILEHANDLE |
1378 | ||
b7df3edc | 1379 | Meaningless. (S<Mac OS>, S<RISC OS>) |
e41182b5 GS |
1380 | |
1381 | Reopens file and restores pointer; if function fails, underlying | |
1382 | filehandle may be closed, or pointer may be in a different position. | |
1383 | (VMS) | |
1384 | ||
1385 | The value returned by C<tell> may be affected after the call, and | |
1386 | the filehandle may be flushed. (Win32) | |
1387 | ||
1388 | =item chmod LIST | |
1389 | ||
b7df3edc | 1390 | Only limited meaning. Disabling/enabling write permission is mapped to |
e41182b5 GS |
1391 | locking/unlocking the file. (S<Mac OS>) |
1392 | ||
1393 | Only good for changing "owner" read-write access, "group", and "other" | |
1394 | bits are meaningless. (Win32) | |
1395 | ||
b8099c3d CN |
1396 | Only good for changing "owner" and "other" read-write access. (S<RISC OS>) |
1397 | ||
495c5fdc PG |
1398 | Access permissions are mapped onto VOS access-control list changes. (VOS) |
1399 | ||
e41182b5 GS |
1400 | =item chown LIST |
1401 | ||
495c5fdc | 1402 | Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>, VOS) |
e41182b5 GS |
1403 | |
1404 | Does nothing, but won't fail. (Win32) | |
1405 | ||
1406 | =item chroot FILENAME | |
1407 | ||
1408 | =item chroot | |
1409 | ||
7c5ffed3 | 1410 | Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>, VOS, VM/ESA) |
e41182b5 GS |
1411 | |
1412 | =item crypt PLAINTEXT,SALT | |
1413 | ||
1414 | May not be available if library or source was not provided when building | |
b8099c3d | 1415 | perl. (Win32) |
e41182b5 | 1416 | |
495c5fdc PG |
1417 | Not implemented. (VOS) |
1418 | ||
e41182b5 GS |
1419 | =item dbmclose HASH |
1420 | ||
495c5fdc | 1421 | Not implemented. (VMS, Plan9, VOS) |
e41182b5 GS |
1422 | |
1423 | =item dbmopen HASH,DBNAME,MODE | |
1424 | ||
495c5fdc | 1425 | Not implemented. (VMS, Plan9, VOS) |
e41182b5 GS |
1426 | |
1427 | =item dump LABEL | |
1428 | ||
b8099c3d | 1429 | Not useful. (S<Mac OS>, S<RISC OS>) |
e41182b5 GS |
1430 | |
1431 | Not implemented. (Win32) | |
1432 | ||
b8099c3d | 1433 | Invokes VMS debugger. (VMS) |
e41182b5 GS |
1434 | |
1435 | =item exec LIST | |
1436 | ||
1437 | Not implemented. (S<Mac OS>) | |
1438 | ||
7c5ffed3 | 1439 | Implemented via Spawn. (VM/ESA) |
3c075c7d | 1440 | |
0f897271 GS |
1441 | Does not automatically flush output handles on some platforms. |
1442 | (SunOS, Solaris, HP-UX) | |
1443 | ||
fe12c0e8 MS |
1444 | =item exit EXPR |
1445 | ||
1446 | =item exit | |
1447 | ||
1448 | Emulates UNIX exit() (which considers C<exit 1> to indicate an error) by | |
1449 | mapping the C<1> to SS$_ABORT (C<44>). This behavior may be overridden | |
1450 | with the pragma C<use vmsish 'exit'>. As with the CRTL's exit() | |
1451 | function, C<exit 0> is also mapped to an exit status of SS$_NORMAL | |
1452 | (C<1>); this mapping cannot be overridden. Any other argument to exit() | |
1453 | is used directly as Perl's exit status. (VMS) | |
1454 | ||
e41182b5 GS |
1455 | =item fcntl FILEHANDLE,FUNCTION,SCALAR |
1456 | ||
1457 | Not implemented. (Win32, VMS) | |
1458 | ||
1459 | =item flock FILEHANDLE,OPERATION | |
1460 | ||
495c5fdc | 1461 | Not implemented (S<Mac OS>, VMS, S<RISC OS>, VOS). |
e41182b5 GS |
1462 | |
1463 | Available only on Windows NT (not on Windows 95). (Win32) | |
1464 | ||
1465 | =item fork | |
1466 | ||
0f897271 GS |
1467 | Not implemented. (S<Mac OS>, AmigaOS, S<RISC OS>, VOS, VM/ESA) |
1468 | ||
1469 | Emulated using multiple interpreters. See L<perlfork>. (Win32) | |
1470 | ||
1471 | Does not automatically flush output handles on some platforms. | |
1472 | (SunOS, Solaris, HP-UX) | |
e41182b5 GS |
1473 | |
1474 | =item getlogin | |
1475 | ||
b8099c3d | 1476 | Not implemented. (S<Mac OS>, S<RISC OS>) |
e41182b5 GS |
1477 | |
1478 | =item getpgrp PID | |
1479 | ||
495c5fdc | 1480 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS) |
e41182b5 GS |
1481 | |
1482 | =item getppid | |
1483 | ||
b8099c3d | 1484 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 GS |
1485 | |
1486 | =item getpriority WHICH,WHO | |
1487 | ||
7c5ffed3 | 1488 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA) |
e41182b5 GS |
1489 | |
1490 | =item getpwnam NAME | |
1491 | ||
1492 | Not implemented. (S<Mac OS>, Win32) | |
1493 | ||
b8099c3d CN |
1494 | Not useful. (S<RISC OS>) |
1495 | ||
e41182b5 GS |
1496 | =item getgrnam NAME |
1497 | ||
b8099c3d | 1498 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 GS |
1499 | |
1500 | =item getnetbyname NAME | |
1501 | ||
1502 | Not implemented. (S<Mac OS>, Win32, Plan9) | |
1503 | ||
1504 | =item getpwuid UID | |
1505 | ||
1506 | Not implemented. (S<Mac OS>, Win32) | |
1507 | ||
b8099c3d CN |
1508 | Not useful. (S<RISC OS>) |
1509 | ||
e41182b5 GS |
1510 | =item getgrgid GID |
1511 | ||
b8099c3d | 1512 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 GS |
1513 | |
1514 | =item getnetbyaddr ADDR,ADDRTYPE | |
1515 | ||
1516 | Not implemented. (S<Mac OS>, Win32, Plan9) | |
1517 | ||
1518 | =item getprotobynumber NUMBER | |
1519 | ||
1520 | Not implemented. (S<Mac OS>) | |
1521 | ||
1522 | =item getservbyport PORT,PROTO | |
1523 | ||
1524 | Not implemented. (S<Mac OS>) | |
1525 | ||
1526 | =item getpwent | |
1527 | ||
7c5ffed3 | 1528 | Not implemented. (S<Mac OS>, Win32, VM/ESA) |
e41182b5 GS |
1529 | |
1530 | =item getgrent | |
1531 | ||
7c5ffed3 | 1532 | Not implemented. (S<Mac OS>, Win32, VMS, VM/ESA) |
e41182b5 GS |
1533 | |
1534 | =item gethostent | |
1535 | ||
1536 | Not implemented. (S<Mac OS>, Win32) | |
1537 | ||
1538 | =item getnetent | |
1539 | ||
1540 | Not implemented. (S<Mac OS>, Win32, Plan9) | |
1541 | ||
1542 | =item getprotoent | |
1543 | ||
1544 | Not implemented. (S<Mac OS>, Win32, Plan9) | |
1545 | ||
1546 | =item getservent | |
1547 | ||
1548 | Not implemented. (Win32, Plan9) | |
1549 | ||
1550 | =item setpwent | |
1551 | ||
b8099c3d | 1552 | Not implemented. (S<Mac OS>, Win32, S<RISC OS>) |
e41182b5 GS |
1553 | |
1554 | =item setgrent | |
1555 | ||
b8099c3d | 1556 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 GS |
1557 | |
1558 | =item sethostent STAYOPEN | |
1559 | ||
b8099c3d | 1560 | Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>) |
e41182b5 GS |
1561 | |
1562 | =item setnetent STAYOPEN | |
1563 | ||
b8099c3d | 1564 | Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>) |
e41182b5 GS |
1565 | |
1566 | =item setprotoent STAYOPEN | |
1567 | ||
b8099c3d | 1568 | Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>) |
e41182b5 GS |
1569 | |
1570 | =item setservent STAYOPEN | |
1571 | ||
b8099c3d | 1572 | Not implemented. (Plan9, Win32, S<RISC OS>) |
e41182b5 GS |
1573 | |
1574 | =item endpwent | |
1575 | ||
a3dfe201 | 1576 | Not implemented. (S<Mac OS>, MPE/iX, VM/ESA, Win32) |
e41182b5 GS |
1577 | |
1578 | =item endgrent | |
1579 | ||
a3dfe201 | 1580 | Not implemented. (S<Mac OS>, MPE/iX, S<RISC OS>, VM/ESA, VMS, Win32) |
e41182b5 GS |
1581 | |
1582 | =item endhostent | |
1583 | ||
1584 | Not implemented. (S<Mac OS>, Win32) | |
1585 | ||
1586 | =item endnetent | |
1587 | ||
1588 | Not implemented. (S<Mac OS>, Win32, Plan9) | |
1589 | ||
1590 | =item endprotoent | |
1591 | ||
1592 | Not implemented. (S<Mac OS>, Win32, Plan9) | |
1593 | ||
1594 | =item endservent | |
1595 | ||
1596 | Not implemented. (Plan9, Win32) | |
1597 | ||
1598 | =item getsockopt SOCKET,LEVEL,OPTNAME | |
1599 | ||
97c10e77 | 1600 | Not implemented. (Plan9) |
e41182b5 GS |
1601 | |
1602 | =item glob EXPR | |
1603 | ||
1604 | =item glob | |
1605 | ||
63f87e49 GS |
1606 | This operator is implemented via the File::Glob extension on most |
1607 | platforms. See L<File::Glob> for portability information. | |
b8099c3d | 1608 | |
e41182b5 GS |
1609 | =item ioctl FILEHANDLE,FUNCTION,SCALAR |
1610 | ||
1611 | Not implemented. (VMS) | |
1612 | ||
1613 | Available only for socket handles, and it does what the ioctlsocket() call | |
1614 | in the Winsock API does. (Win32) | |
1615 | ||
b8099c3d CN |
1616 | Available only for socket handles. (S<RISC OS>) |
1617 | ||
b350dd2f | 1618 | =item kill SIGNAL, LIST |
e41182b5 | 1619 | |
862b5365 JH |
1620 | C<kill(0, LIST)> is implemented for the sake of taint checking; |
1621 | use with other signals is unimplemented. (S<Mac OS>) | |
1622 | ||
1623 | Not implemented, hence not useful for taint checking. (S<RISC OS>) | |
e41182b5 | 1624 | |
63f87e49 GS |
1625 | C<kill()> doesn't have the semantics of C<raise()>, i.e. it doesn't send |
1626 | a signal to the identified process like it does on Unix platforms. | |
1627 | Instead C<kill($sig, $pid)> terminates the process identified by $pid, | |
1628 | and makes it exit immediately with exit status $sig. As in Unix, if | |
1629 | $sig is 0 and the specified process exists, it returns true without | |
1630 | actually terminating it. (Win32) | |
e41182b5 GS |
1631 | |
1632 | =item link OLDFILE,NEWFILE | |
1633 | ||
a3dfe201 | 1634 | Not implemented. (S<Mac OS>, MPE/iX, VMS, S<RISC OS>) |
e41182b5 | 1635 | |
433acd8a JH |
1636 | Link count not updated because hard links are not quite that hard |
1637 | (They are sort of half-way between hard and soft links). (AmigaOS) | |
1638 | ||
a3dfe201 GS |
1639 | Hard links are implemented on Win32 (Windows NT and Windows 2000) |
1640 | under NTFS only. | |
1641 | ||
e41182b5 GS |
1642 | =item lstat FILEHANDLE |
1643 | ||
1644 | =item lstat EXPR | |
1645 | ||
1646 | =item lstat | |
1647 | ||
b8099c3d | 1648 | Not implemented. (VMS, S<RISC OS>) |
e41182b5 | 1649 | |
63f87e49 | 1650 | Return values (especially for device and inode) may be bogus. (Win32) |
e41182b5 GS |
1651 | |
1652 | =item msgctl ID,CMD,ARG | |
1653 | ||
1654 | =item msgget KEY,FLAGS | |
1655 | ||
1656 | =item msgsnd ID,MSG,FLAGS | |
1657 | ||
1658 | =item msgrcv ID,VAR,SIZE,TYPE,FLAGS | |
1659 | ||
495c5fdc | 1660 | Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>, VOS) |
e41182b5 GS |
1661 | |
1662 | =item open FILEHANDLE,EXPR | |
1663 | ||
1664 | =item open FILEHANDLE | |
1665 | ||
b7df3edc | 1666 | The C<|> variants are supported only if ToolServer is installed. |
e41182b5 GS |
1667 | (S<Mac OS>) |
1668 | ||
c47ff5f1 | 1669 | open to C<|-> and C<-|> are unsupported. (S<Mac OS>, Win32, S<RISC OS>) |
e41182b5 | 1670 | |
0f897271 GS |
1671 | Opening a process does not automatically flush output handles on some |
1672 | platforms. (SunOS, Solaris, HP-UX) | |
1673 | ||
e41182b5 GS |
1674 | =item pipe READHANDLE,WRITEHANDLE |
1675 | ||
433acd8a JH |
1676 | Very limited functionality. (MiNT) |
1677 | ||
e41182b5 GS |
1678 | =item readlink EXPR |
1679 | ||
1680 | =item readlink | |
1681 | ||
b8099c3d | 1682 | Not implemented. (Win32, VMS, S<RISC OS>) |
e41182b5 GS |
1683 | |
1684 | =item select RBITS,WBITS,EBITS,TIMEOUT | |
1685 | ||
689c5c24 | 1686 | Only implemented on sockets. (Win32, VMS) |
e41182b5 | 1687 | |
b8099c3d CN |
1688 | Only reliable on sockets. (S<RISC OS>) |
1689 | ||
76e05f0b | 1690 | Note that the C<select FILEHANDLE> form is generally portable. |
63f87e49 | 1691 | |
e41182b5 GS |
1692 | =item semctl ID,SEMNUM,CMD,ARG |
1693 | ||
1694 | =item semget KEY,NSEMS,FLAGS | |
1695 | ||
1696 | =item semop KEY,OPSTRING | |
1697 | ||
495c5fdc | 1698 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS) |
e41182b5 | 1699 | |
a3dfe201 GS |
1700 | =item setgrent |
1701 | ||
1702 | Not implemented. (MPE/iX, Win32) | |
1703 | ||
e41182b5 GS |
1704 | =item setpgrp PID,PGRP |
1705 | ||
495c5fdc | 1706 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS) |
e41182b5 GS |
1707 | |
1708 | =item setpriority WHICH,WHO,PRIORITY | |
1709 | ||
495c5fdc | 1710 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS) |
e41182b5 | 1711 | |
a3dfe201 GS |
1712 | =item setpwent |
1713 | ||
1714 | Not implemented. (MPE/iX, Win32) | |
1715 | ||
e41182b5 GS |
1716 | =item setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL |
1717 | ||
97c10e77 | 1718 | Not implemented. (Plan9) |
e41182b5 GS |
1719 | |
1720 | =item shmctl ID,CMD,ARG | |
1721 | ||
1722 | =item shmget KEY,SIZE,FLAGS | |
1723 | ||
1724 | =item shmread ID,VAR,POS,SIZE | |
1725 | ||
1726 | =item shmwrite ID,STRING,POS,SIZE | |
1727 | ||
495c5fdc | 1728 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS) |
e41182b5 | 1729 | |
80cbd5ad JH |
1730 | =item sockatmark SOCKET |
1731 | ||
1732 | A relatively recent addition to socket functions, may not | |
1733 | be implemented even in UNIX platforms. | |
1734 | ||
e41182b5 GS |
1735 | =item socketpair SOCKET1,SOCKET2,DOMAIN,TYPE,PROTOCOL |
1736 | ||
862b5365 | 1737 | Not implemented. (Win32, VMS, S<RISC OS>, VOS, VM/ESA) |
e41182b5 GS |
1738 | |
1739 | =item stat FILEHANDLE | |
1740 | ||
1741 | =item stat EXPR | |
1742 | ||
1743 | =item stat | |
1744 | ||
d62e1b7f JH |
1745 | Platforms that do not have rdev, blksize, or blocks will return these |
1746 | as '', so numeric comparison or manipulation of these fields may cause | |
1747 | 'not numeric' warnings. | |
1748 | ||
e41182b5 GS |
1749 | mtime and atime are the same thing, and ctime is creation time instead of |
1750 | inode change time. (S<Mac OS>) | |
1751 | ||
1752 | device and inode are not meaningful. (Win32) | |
1753 | ||
1754 | device and inode are not necessarily reliable. (VMS) | |
1755 | ||
b8099c3d CN |
1756 | mtime, atime and ctime all return the last modification time. Device and |
1757 | inode are not necessarily reliable. (S<RISC OS>) | |
1758 | ||
d62e1b7f JH |
1759 | dev, rdev, blksize, and blocks are not available. inode is not |
1760 | meaningful and will differ between stat calls on the same file. (os2) | |
1761 | ||
73e9292c JH |
1762 | some versions of cygwin when doing a stat("foo") and if not finding it |
1763 | may then attempt to stat("foo.exe") (Cygwin) | |
1764 | ||
e41182b5 GS |
1765 | =item symlink OLDFILE,NEWFILE |
1766 | ||
b8099c3d | 1767 | Not implemented. (Win32, VMS, S<RISC OS>) |
e41182b5 GS |
1768 | |
1769 | =item syscall LIST | |
1770 | ||
7c5ffed3 | 1771 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA) |
e41182b5 | 1772 | |
f34d0673 GS |
1773 | =item sysopen FILEHANDLE,FILENAME,MODE,PERMS |
1774 | ||
dd9f0070 | 1775 | The traditional "0", "1", and "2" MODEs are implemented with different |
322422de GS |
1776 | numeric values on some systems. The flags exported by C<Fcntl> |
1777 | (O_RDONLY, O_WRONLY, O_RDWR) should work everywhere though. (S<Mac | |
7c5ffed3 | 1778 | OS>, OS/390, VM/ESA) |
f34d0673 | 1779 | |
e41182b5 GS |
1780 | =item system LIST |
1781 | ||
9d6eb86e | 1782 | In general, do not assume the UNIX/POSIX semantics that you can shift |
7717d0e7 | 1783 | C<$?> right by eight to get the exit value, or that C<$? & 127> |
9d6eb86e JH |
1784 | would give you the number of the signal that terminated the program, |
1785 | or that C<$? & 128> would test true if the program was terminated by a | |
1786 | coredump. Instead, use the POSIX W*() interfaces: for example, use | |
1787 | WIFEXITED($?) an WEXITVALUE($?) to test for a normal exit and the exit | |
1788 | value, and WIFSIGNALED($?) and WTERMSIG($?) for a signal exit and the | |
7717d0e7 | 1789 | signal. Core dumping is not a portable concept, so there's no portable |
9d6eb86e JH |
1790 | way to test for that. |
1791 | ||
e41182b5 GS |
1792 | Only implemented if ToolServer is installed. (S<Mac OS>) |
1793 | ||
1794 | As an optimization, may not call the command shell specified in | |
b7df3edc | 1795 | C<$ENV{PERL5SHELL}>. C<system(1, @args)> spawns an external |
e41182b5 GS |
1796 | process and immediately returns its process designator, without |
1797 | waiting for it to terminate. Return value may be used subsequently | |
63f87e49 GS |
1798 | in C<wait> or C<waitpid>. Failure to spawn() a subprocess is indicated |
1799 | by setting $? to "255 << 8". C<$?> is set in a way compatible with | |
1800 | Unix (i.e. the exitstatus of the subprocess is obtained by "$? >> 8", | |
1801 | as described in the documentation). (Win32) | |
e41182b5 | 1802 | |
b8099c3d CN |
1803 | There is no shell to process metacharacters, and the native standard is |
1804 | to pass a command line terminated by "\n" "\r" or "\0" to the spawned | |
c47ff5f1 | 1805 | program. Redirection such as C<< > foo >> is performed (if at all) by |
b8099c3d CN |
1806 | the run time library of the spawned program. C<system> I<list> will call |
1807 | the Unix emulation library's C<exec> emulation, which attempts to provide | |
1808 | emulation of the stdin, stdout, stderr in force in the parent, providing | |
1809 | the child program uses a compatible version of the emulation library. | |
1810 | I<scalar> will call the native command line direct and no such emulation | |
1811 | of a child Unix program will exists. Mileage B<will> vary. (S<RISC OS>) | |
1812 | ||
433acd8a JH |
1813 | Far from being POSIX compliant. Because there may be no underlying |
1814 | /bin/sh tries to work around the problem by forking and execing the | |
9b63e9ec | 1815 | first token in its argument string. Handles basic redirection |
c47ff5f1 | 1816 | ("<" or ">") on its own behalf. (MiNT) |
433acd8a | 1817 | |
0f897271 GS |
1818 | Does not automatically flush output handles on some platforms. |
1819 | (SunOS, Solaris, HP-UX) | |
1820 | ||
9bc98430 CB |
1821 | The return value is POSIX-like (shifted up by 8 bits), which only allows |
1822 | room for a made-up value derived from the severity bits of the native | |
1823 | 32-bit condition code (unless overridden by C<use vmsish 'status'>). | |
1824 | For more details see L<perlvms/$?>. (VMS) | |
1825 | ||
e41182b5 GS |
1826 | =item times |
1827 | ||
1828 | Only the first entry returned is nonzero. (S<Mac OS>) | |
1829 | ||
63f87e49 GS |
1830 | "cumulative" times will be bogus. On anything other than Windows NT |
1831 | or Windows 2000, "system" time will be bogus, and "user" time is | |
1832 | actually the time returned by the clock() function in the C runtime | |
1833 | library. (Win32) | |
e41182b5 | 1834 | |
b8099c3d CN |
1835 | Not useful. (S<RISC OS>) |
1836 | ||
e41182b5 GS |
1837 | =item truncate FILEHANDLE,LENGTH |
1838 | ||
1839 | =item truncate EXPR,LENGTH | |
1840 | ||
6d738113 | 1841 | Not implemented. (Older versions of VMS) |
e41182b5 | 1842 | |
495c5fdc PG |
1843 | Truncation to zero-length only. (VOS) |
1844 | ||
4cfdb94f | 1845 | If a FILEHANDLE is supplied, it must be writable and opened in append |
e71a7dc8 | 1846 | mode (i.e., use C<<< open(FH, '>>filename') >>> |
4cfdb94f GS |
1847 | or C<sysopen(FH,...,O_APPEND|O_RDWR)>. If a filename is supplied, it |
1848 | should not be held open elsewhere. (Win32) | |
1849 | ||
e41182b5 GS |
1850 | =item umask EXPR |
1851 | ||
1852 | =item umask | |
1853 | ||
1854 | Returns undef where unavailable, as of version 5.005. | |
1855 | ||
b7df3edc GS |
1856 | C<umask> works but the correct permissions are set only when the file |
1857 | is finally closed. (AmigaOS) | |
433acd8a | 1858 | |
e41182b5 GS |
1859 | =item utime LIST |
1860 | ||
15c65113 | 1861 | Only the modification time is updated. (S<BeOS>, S<Mac OS>, VMS, S<RISC OS>) |
e41182b5 | 1862 | |
322422de GS |
1863 | May not behave as expected. Behavior depends on the C runtime |
1864 | library's implementation of utime(), and the filesystem being | |
1865 | used. The FAT filesystem typically does not support an "access | |
1866 | time" field, and it may limit timestamps to a granularity of | |
1867 | two seconds. (Win32) | |
e41182b5 GS |
1868 | |
1869 | =item wait | |
1870 | ||
1871 | =item waitpid PID,FLAGS | |
1872 | ||
495c5fdc | 1873 | Not implemented. (S<Mac OS>, VOS) |
e41182b5 GS |
1874 | |
1875 | Can only be applied to process handles returned for processes spawned | |
a6f858fb | 1876 | using C<system(1, ...)> or pseudo processes created with C<fork()>. (Win32) |
e41182b5 | 1877 | |
b8099c3d CN |
1878 | Not useful. (S<RISC OS>) |
1879 | ||
e41182b5 GS |
1880 | =back |
1881 | ||
b8099c3d CN |
1882 | =head1 CHANGES |
1883 | ||
1884 | =over 4 | |
1885 | ||
fd46a41b JH |
1886 | =item v1.48, 02 February 2001 |
1887 | ||
1888 | Various updates from perl5-porters over the past year, supported | |
1889 | platforms update from Jarkko Hietaniemi. | |
1890 | ||
c997b287 GS |
1891 | =item v1.47, 22 March 2000 |
1892 | ||
1893 | Various cleanups from Tom Christiansen, including migration of | |
1894 | long platform listings from L<perl>. | |
1895 | ||
56d7751a GS |
1896 | =item v1.46, 12 February 2000 |
1897 | ||
1898 | Updates for VOS and MPE/iX. (Peter Prymmer) Other small changes. | |
1899 | ||
0cc436d0 GS |
1900 | =item v1.45, 20 December 1999 |
1901 | ||
1902 | Small changes from 5.005_63 distribution, more changes to EBCDIC info. | |
1903 | ||
d1e3b762 GS |
1904 | =item v1.44, 19 July 1999 |
1905 | ||
1906 | A bunch of updates from Peter Prymmer for C<$^O> values, | |
1907 | endianness, File::Spec, VMS, BS2000, OS/400. | |
1908 | ||
b7df3edc GS |
1909 | =item v1.43, 24 May 1999 |
1910 | ||
1911 | Added a lot of cleaning up from Tom Christiansen. | |
1912 | ||
19799a22 | 1913 | =item v1.42, 22 May 1999 |
b7df3edc | 1914 | |
19799a22 | 1915 | Added notes about tests, sprintf/printf, and epoch offsets. |
b7df3edc | 1916 | |
6ab3f9cb GS |
1917 | =item v1.41, 19 May 1999 |
1918 | ||
1919 | Lots more little changes to formatting and content. | |
1920 | ||
d1e3b762 | 1921 | Added a bunch of C<$^O> and related values |
6ab3f9cb GS |
1922 | for various platforms; fixed mail and web addresses, and added |
1923 | and changed miscellaneous notes. (Peter Prymmer) | |
1924 | ||
1925 | =item v1.40, 11 April 1999 | |
1926 | ||
1927 | Miscellaneous changes. | |
1928 | ||
1929 | =item v1.39, 11 February 1999 | |
2ee0eb3c CN |
1930 | |
1931 | Changes from Jarkko and EMX URL fixes Michael Schwern. Additional | |
1932 | note about newlines added. | |
1933 | ||
9b63e9ec CN |
1934 | =item v1.38, 31 December 1998 |
1935 | ||
1936 | More changes from Jarkko. | |
1937 | ||
3c075c7d CN |
1938 | =item v1.37, 19 December 1998 |
1939 | ||
1940 | More minor changes. Merge two separate version 1.35 documents. | |
1941 | ||
1942 | =item v1.36, 9 September 1998 | |
1943 | ||
1944 | Updated for Stratus VOS. Also known as version 1.35. | |
1945 | ||
1946 | =item v1.35, 13 August 1998 | |
495c5fdc | 1947 | |
3c075c7d CN |
1948 | Integrate more minor changes, plus addition of new sections under |
1949 | L<"ISSUES">: L<"Numbers endianness and Width">, | |
1950 | L<"Character sets and character encoding">, | |
1951 | L<"Internationalisation">. | |
495c5fdc | 1952 | |
3c075c7d | 1953 | =item v1.33, 06 August 1998 |
0a47030a GS |
1954 | |
1955 | Integrate more minor changes. | |
1956 | ||
3c075c7d | 1957 | =item v1.32, 05 August 1998 |
dd9f0070 CN |
1958 | |
1959 | Integrate more minor changes. | |
1960 | ||
3c075c7d | 1961 | =item v1.30, 03 August 1998 |
b8099c3d CN |
1962 | |
1963 | Major update for RISC OS, other minor changes. | |
1964 | ||
3c075c7d | 1965 | =item v1.23, 10 July 1998 |
b8099c3d CN |
1966 | |
1967 | First public release with perl5.005. | |
1968 | ||
1969 | =back | |
e41182b5 | 1970 | |
ba58ab26 JH |
1971 | =head1 Supported Platforms |
1972 | ||
9ca74005 JH |
1973 | As of early 2001 (the Perl releases 5.6.1 and 5.7.1), the following |
1974 | platforms are able to build Perl from the standard source code | |
a93751fa | 1975 | distribution available at http://www.cpan.org/src/index.html |
ba58ab26 JH |
1976 | |
1977 | AIX | |
fd46a41b | 1978 | AmigaOS |
b787fad4 | 1979 | Darwin (Mac OS X) |
fd46a41b | 1980 | DG/UX |
ba58ab26 | 1981 | DOS DJGPP 1) |
fd46a41b | 1982 | DYNIX/ptx |
6ba81f13 | 1983 | EPOC |
ba58ab26 JH |
1984 | FreeBSD |
1985 | HP-UX | |
1986 | IRIX | |
1987 | Linux | |
ba58ab26 | 1988 | MachTen |
fd46a41b JH |
1989 | MacOS Classic 2) |
1990 | NonStop-UX | |
1991 | ReliantUNIX (SINIX) | |
ba58ab26 | 1992 | OpenBSD |
fd46a41b | 1993 | OpenVMS (VMS) |
ba58ab26 | 1994 | OS/2 |
fd46a41b | 1995 | OS X |
ba58ab26 | 1996 | QNX |
ba58ab26 | 1997 | Solaris |
fd46a41b | 1998 | Tru64 UNIX (DEC OSF/1, Digital UNIX) |
ba58ab26 JH |
1999 | UNICOS |
2000 | UNICOS/mk | |
ba58ab26 | 2001 | VOS |
fd46a41b | 2002 | Win32/NT/2K 3) |
ba58ab26 JH |
2003 | |
2004 | 1) in DOS mode either the DOS or OS/2 ports can be used | |
fd46a41b JH |
2005 | 2) Mac OS Classic (pre-X) is almost 5.6.1-ready; building from |
2006 | the source does work with 5.6.1, but additional MacOS specific | |
862b5365 JH |
2007 | source code is needed for a complete build. See the web |
2008 | site http://dev.macperl.org/ for more information. | |
fd46a41b | 2009 | 3) compilers: Borland, Cygwin, Mingw32 EGCS/GCC, VC++ |
ba58ab26 | 2010 | |
9ca74005 JH |
2011 | The following platforms worked for the previous releases (5.6.0 and 5.7.0), |
2012 | but we did not manage to test these in time for the 5.7.1 release. | |
2013 | There is a very good chance that these will work fine with the 5.7.1. | |
ba58ab26 | 2014 | |
ba58ab26 JH |
2015 | DomainOS |
2016 | Hurd | |
fd46a41b JH |
2017 | LynxOS |
2018 | MinGW | |
2019 | MPE/iX | |
2020 | NetBSD | |
ba58ab26 | 2021 | PowerMAX |
fd46a41b | 2022 | SCO SV |
ba58ab26 | 2023 | SunOS |
fd46a41b JH |
2024 | SVR4 |
2025 | Unixware | |
2026 | Windows 3.1 | |
2027 | Windows 95 | |
2028 | Windows 98 | |
2029 | Windows Me | |
ba58ab26 | 2030 | |
fd46a41b | 2031 | The following platform worked for the 5.005_03 major release but not |
9ca74005 JH |
2032 | for 5.6.0. Standardization on UTF-8 as the internal string |
2033 | representation in 5.6.0 and 5.6.1 introduced incompatibilities in this | |
2034 | EBCDIC platform. While Perl 5.7.1 will build on this platform some | |
fd46a41b | 2035 | regression tests may fail and the C<use utf8;> pragma typically |
9ca74005 | 2036 | introduces text handling errors. |
ba58ab26 | 2037 | |
fd46a41b | 2038 | OS/390 1) |
ba58ab26 | 2039 | |
fd46a41b | 2040 | 1) previously known as MVS, about to become z/OS. |
ba58ab26 | 2041 | |
fd46a41b | 2042 | Strongly related to the OS/390 platform by also being EBCDIC-based |
ba58ab26 JH |
2043 | mainframe platforms are the following platforms: |
2044 | ||
fd46a41b | 2045 | POSIX-BC (BS2000) |
ba58ab26 JH |
2046 | VM/ESA |
2047 | ||
fd46a41b JH |
2048 | These are also expected to work, albeit with no UTF-8 support, under 5.6.1 |
2049 | for the same reasons as OS/390. Contact the mailing list perl-mvs@perl.org | |
2050 | for more details. | |
ba58ab26 JH |
2051 | |
2052 | The following platforms have been known to build Perl from source in | |
fd46a41b JH |
2053 | the past (5.005_03 and earlier), but we haven't been able to verify |
2054 | their status for the current release, either because the | |
2055 | hardware/software platforms are rare or because we don't have an | |
2056 | active champion on these platforms--or both. They used to work, | |
2057 | though, so go ahead and try compiling them, and let perlbug@perl.org | |
2058 | of any trouble. | |
ba58ab26 JH |
2059 | |
2060 | 3b1 | |
fd46a41b JH |
2061 | A/UX |
2062 | BeOS | |
2063 | BSD/OS | |
ba58ab26 JH |
2064 | ConvexOS |
2065 | CX/UX | |
2066 | DC/OSx | |
2067 | DDE SMES | |
2068 | DOS EMX | |
2069 | Dynix | |
2070 | EP/IX | |
2071 | ESIX | |
2072 | FPS | |
2073 | GENIX | |
2074 | Greenhills | |
2075 | ISC | |
2076 | MachTen 68k | |
2077 | MiNT | |
2078 | MPC | |
2079 | NEWS-OS | |
fd46a41b JH |
2080 | NextSTEP |
2081 | OpenSTEP | |
ba58ab26 JH |
2082 | Opus |
2083 | Plan 9 | |
2084 | PowerUX | |
2085 | RISC/os | |
fd46a41b | 2086 | SCO ODT/OSR |
ba58ab26 JH |
2087 | Stellar |
2088 | SVR2 | |
2089 | TI1500 | |
2090 | TitanOS | |
fd46a41b | 2091 | Ultrix |
ba58ab26 JH |
2092 | Unisys Dynix |
2093 | Unixware | |
fd46a41b | 2094 | UTS |
ba58ab26 JH |
2095 | |
2096 | Support for the following platform is planned for a future Perl release: | |
2097 | ||
2098 | Netware | |
2099 | ||
2100 | The following platforms have their own source code distributions and | |
a93751fa | 2101 | binaries available via http://www.cpan.org/ports/index.html: |
ba58ab26 JH |
2102 | |
2103 | Perl release | |
2104 | ||
ba58ab26 | 2105 | Netware 5.003_07 |
fd46a41b | 2106 | OS/400 5.005_02 |
ba58ab26 JH |
2107 | Tandem Guardian 5.004 |
2108 | ||
2109 | The following platforms have only binaries available via | |
a93751fa | 2110 | http://www.cpan.org/ports/index.html : |
ba58ab26 JH |
2111 | |
2112 | Perl release | |
2113 | ||
2114 | Acorn RISCOS 5.005_02 | |
2115 | AOS 5.002 | |
2116 | LynxOS 5.004_02 | |
2117 | ||
2118 | Although we do suggest that you always build your own Perl from | |
2119 | the source code, both for maximal configurability and for security, | |
2120 | in case you are in a hurry you can check | |
a93751fa | 2121 | http://www.cpan.org/ports/index.html for binary distributions. |
ba58ab26 | 2122 | |
c997b287 GS |
2123 | =head1 SEE ALSO |
2124 | ||
a83b6f46 | 2125 | L<perlaix>, L<perlapollo>, L<perlamiga>, L<perlbeos>, L<perlbs200>, |
a1f19229 | 2126 | L<perlce>, L<perlcygwin>, L<perldgux>, L<perldos>, L<perlepoc>, L<perlebcdic>, |
a83b6f46 | 2127 | L<perlhurd>, L<perlhpux>, L<perlmachten>, L<perlmacos>, L<perlmint>, |
9038e305 JH |
2128 | L<perlmpeix>, L<perlnetware>, L<perlos2>, L<perlos390>, L<perlplan9>, |
2129 | L<perlqnx>, L<perlsolaris>, L<perltru64>, L<perlunicode>, | |
2130 | L<perlvmesa>, L<perlvms>, L<perlvos>, L<perlwin32>, and L<Win32>. | |
c997b287 | 2131 | |
e41182b5 GS |
2132 | =head1 AUTHORS / CONTRIBUTORS |
2133 | ||
06e9666b | 2134 | Abigail <abigail@foad.org>, |
c47ff5f1 GS |
2135 | Charles Bailey <bailey@newman.upenn.edu>, |
2136 | Graham Barr <gbarr@pobox.com>, | |
2137 | Tom Christiansen <tchrist@perl.com>, | |
06e9666b | 2138 | Nicholas Clark <nick@ccl4.org>, |
c47ff5f1 | 2139 | Thomas Dorner <Thomas.Dorner@start.de>, |
06e9666b A |
2140 | Andy Dougherty <doughera@lafayette.edu>, |
2141 | Dominic Dunlop <domo@computer.org>, | |
2142 | Neale Ferguson <neale@vma.tabnsw.com.au>, | |
c47ff5f1 GS |
2143 | David J. Fiander <davidf@mks.com>, |
2144 | Paul Green <Paul_Green@stratus.com>, | |
06e9666b | 2145 | M.J.T. Guy <mjtg@cam.ac.uk>, |
61f30a5e | 2146 | Jarkko Hietaniemi <jhi@iki.fi>, |
c47ff5f1 | 2147 | Luther Huffman <lutherh@stratcom.com>, |
06e9666b A |
2148 | Nick Ing-Simmons <nick@ing-simmons.net>, |
2149 | Andreas J. KE<ouml>nig <a.koenig@mind.de>, | |
c47ff5f1 GS |
2150 | Markus Laker <mlaker@contax.co.uk>, |
2151 | Andrew M. Langmead <aml@world.std.com>, | |
2152 | Larry Moore <ljmoore@freespace.net>, | |
2153 | Paul Moore <Paul.Moore@uk.origin-it.com>, | |
2154 | Chris Nandor <pudge@pobox.com>, | |
2155 | Matthias Neeracher <neeri@iis.ee.ethz.ch>, | |
e71a7dc8 | 2156 | Philip Newton <pne@cpan.org>, |
c47ff5f1 GS |
2157 | Gary Ng <71564.1743@CompuServe.COM>, |
2158 | Tom Phoenix <rootbeer@teleport.com>, | |
2159 | AndrE<eacute> Pirard <A.Pirard@ulg.ac.be>, | |
2160 | Peter Prymmer <pvhp@forte.com>, | |
2161 | Hugo van der Sanden <hv@crypt0.demon.co.uk>, | |
2162 | Gurusamy Sarathy <gsar@activestate.com>, | |
2163 | Paul J. Schinder <schinder@pobox.com>, | |
2164 | Michael G Schwern <schwern@pobox.com>, | |
06e9666b | 2165 | Dan Sugalski <dan@sidhe.org>, |
c47ff5f1 | 2166 | Nathan Torkington <gnat@frii.com>. |
e41182b5 | 2167 | |
e41182b5 GS |
2168 | =head1 VERSION |
2169 | ||
b787fad4 | 2170 | Version 1.50, last modified 10 Jul 2001 |