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1=head1 NAME
2
3perlport - Writing portable Perl
4
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5=head1 DESCRIPTION
6
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7Perl runs on numerous operating systems. While most of them share
8much in common, they also have their own unique features.
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9
10This document is meant to help you to find out what constitutes portable
b7df3edc 11Perl code. That way once you make a decision to write portably,
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12you know where the lines are drawn, and you can stay within them.
13
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14There is a tradeoff between taking full advantage of one particular
15type of computer and taking advantage of a full range of them.
16Naturally, as you broaden your range and become more diverse, the
17common factors drop, and you are left with an increasingly smaller
18area of common ground in which you can operate to accomplish a
19particular task. Thus, when you begin attacking a problem, it is
20important to consider under which part of the tradeoff curve you
21want to operate. Specifically, you must decide whether it is
22important that the task that you are coding have the full generality
23of being portable, or whether to just get the job done right now.
24This is the hardest choice to be made. The rest is easy, because
25Perl provides many choices, whichever way you want to approach your
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26problem.
27
28Looking at it another way, writing portable code is usually about
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29willfully limiting your available choices. Naturally, it takes
30discipline and sacrifice to do that. The product of portability
31and convenience may be a constant. You have been warned.
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32
33Be aware of two important points:
34
35=over 4
36
37=item Not all Perl programs have to be portable
38
b7df3edc 39There is no reason you should not use Perl as a language to glue Unix
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40tools together, or to prototype a Macintosh application, or to manage the
41Windows registry. If it makes no sense to aim for portability for one
42reason or another in a given program, then don't bother.
43
b7df3edc 44=item Nearly all of Perl already I<is> portable
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45
46Don't be fooled into thinking that it is hard to create portable Perl
47code. It isn't. Perl tries its level-best to bridge the gaps between
48what's available on different platforms, and all the means available to
49use those features. Thus almost all Perl code runs on any machine
6ab3f9cb 50without modification. But there are some significant issues in
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51writing portable code, and this document is entirely about those issues.
52
53=back
54
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55Here's the general rule: When you approach a task commonly done
56using a whole range of platforms, think about writing portable
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57code. That way, you don't sacrifice much by way of the implementation
58choices you can avail yourself of, and at the same time you can give
59your users lots of platform choices. On the other hand, when you have to
60take advantage of some unique feature of a particular platform, as is
61often the case with systems programming (whether for Unix, Windows,
62S<Mac OS>, VMS, etc.), consider writing platform-specific code.
63
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64When the code will run on only two or three operating systems, you
65may need to consider only the differences of those particular systems.
66The important thing is to decide where the code will run and to be
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67deliberate in your decision.
68
69The material below is separated into three main sections: main issues of
7ee27b7c 70portability (L<"ISSUES">), platform-specific issues (L<"PLATFORMS">), and
b7df3edc 71built-in perl functions that behave differently on various ports
7ee27b7c 72(L<"FUNCTION IMPLEMENTATIONS">).
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73
74This information should not be considered complete; it includes possibly
b8099c3d 75transient information about idiosyncrasies of some of the ports, almost
b7df3edc 76all of which are in a state of constant evolution. Thus, this material
e41182b5 77should be considered a perpetual work in progress
cc07ed0b 78(C<< <IMG SRC="yellow_sign.gif" ALT="Under Construction"> >>).
e41182b5 79
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80=head1 ISSUES
81
82=head2 Newlines
83
638bc118 84In most operating systems, lines in files are terminated by newlines.
e41182b5 85Just what is used as a newline may vary from OS to OS. Unix
b7df3edc 86traditionally uses C<\012>, one type of DOSish I/O uses C<\015\012>,
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87and S<Mac OS> uses C<\015>.
88
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89Perl uses C<\n> to represent the "logical" newline, where what is
90logical may depend on the platform in use. In MacPerl, C<\n> always
51d9476f 91means C<\015>. In DOSish perls, C<\n> usually means C<\012>, but when
92accessing a file in "text" mode, perl uses the C<:crlf> layer that
93translates it to (or from) C<\015\012>, depending on whether you're
94reading or writing. Unix does the same thing on ttys in canonical
95mode. C<\015\012> is commonly referred to as CRLF.
b7df3edc 96
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97To trim trailing newlines from text lines use chomp(). With default
98settings that function looks for a trailing C<\n> character and thus
99trims in a portable way.
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100
101When dealing with binary files (or text files in binary mode) be sure
102to explicitly set $/ to the appropriate value for your file format
103before using chomp().
104
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105Because of the "text" mode translation, DOSish perls have limitations
106in using C<seek> and C<tell> on a file accessed in "text" mode.
107Stick to C<seek>-ing to locations you got from C<tell> (and no
108others), and you are usually free to use C<seek> and C<tell> even
109in "text" mode. Using C<seek> or C<tell> or other file operations
110may be non-portable. If you use C<binmode> on a file, however, you
111can usually C<seek> and C<tell> with arbitrary values in safety.
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112
113A common misconception in socket programming is that C<\n> eq C<\012>
0a47030a 114everywhere. When using protocols such as common Internet protocols,
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115C<\012> and C<\015> are called for specifically, and the values of
116the logical C<\n> and C<\r> (carriage return) are not reliable.
117
118 print SOCKET "Hi there, client!\r\n"; # WRONG
119 print SOCKET "Hi there, client!\015\012"; # RIGHT
120
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121However, using C<\015\012> (or C<\cM\cJ>, or C<\x0D\x0A>) can be tedious
122and unsightly, as well as confusing to those maintaining the code. As
6ab3f9cb 123such, the Socket module supplies the Right Thing for those who want it.
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124
125 use Socket qw(:DEFAULT :crlf);
126 print SOCKET "Hi there, client!$CRLF" # RIGHT
127
6ab3f9cb 128When reading from a socket, remember that the default input record
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129separator C<$/> is C<\n>, but robust socket code will recognize as
130either C<\012> or C<\015\012> as end of line:
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131
132 while (<SOCKET>) {
133 # ...
134 }
135
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136Because both CRLF and LF end in LF, the input record separator can
137be set to LF and any CR stripped later. Better to write:
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138
139 use Socket qw(:DEFAULT :crlf);
140 local($/) = LF; # not needed if $/ is already \012
141
142 while (<SOCKET>) {
143 s/$CR?$LF/\n/; # not sure if socket uses LF or CRLF, OK
144 # s/\015?\012/\n/; # same thing
145 }
146
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147This example is preferred over the previous one--even for Unix
148platforms--because now any C<\015>'s (C<\cM>'s) are stripped out
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149(and there was much rejoicing).
150
6ab3f9cb 151Similarly, functions that return text data--such as a function that
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152fetches a web page--should sometimes translate newlines before
153returning the data, if they've not yet been translated to the local
154newline representation. A single line of code will often suffice:
2ee0eb3c 155
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156 $data =~ s/\015?\012/\n/g;
157 return $data;
2ee0eb3c 158
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159Some of this may be confusing. Here's a handy reference to the ASCII CR
160and LF characters. You can print it out and stick it in your wallet.
161
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162 LF eq \012 eq \x0A eq \cJ eq chr(10) eq ASCII 10
163 CR eq \015 eq \x0D eq \cM eq chr(13) eq ASCII 13
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164
165 | Unix | DOS | Mac |
166 ---------------------------
167 \n | LF | LF | CR |
168 \r | CR | CR | LF |
169 \n * | LF | CRLF | CR |
170 \r * | CR | CR | LF |
171 ---------------------------
172 * text-mode STDIO
173
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174The Unix column assumes that you are not accessing a serial line
175(like a tty) in canonical mode. If you are, then CR on input becomes
176"\n", and "\n" on output becomes CRLF.
177
6ab3f9cb 178These are just the most common definitions of C<\n> and C<\r> in Perl.
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179There may well be others. For example, on an EBCDIC implementation
180such as z/OS (OS/390) or OS/400 (using the ILE, the PASE is ASCII-based)
181the above material is similar to "Unix" but the code numbers change:
74555b7a 182
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183 LF eq \025 eq \x15 eq \cU eq chr(21) eq CP-1047 21
184 LF eq \045 eq \x25 eq chr(37) eq CP-0037 37
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185 CR eq \015 eq \x0D eq \cM eq chr(13) eq CP-1047 13
186 CR eq \015 eq \x0D eq \cM eq chr(13) eq CP-0037 13
187
188 | z/OS | OS/400 |
189 ----------------------
190 \n | LF | LF |
191 \r | CR | CR |
192 \n * | LF | LF |
193 \r * | CR | CR |
194 ----------------------
195 * text-mode STDIO
6ab3f9cb 196
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197=head2 Numbers endianness and Width
198
199Different CPUs store integers and floating point numbers in different
200orders (called I<endianness>) and widths (32-bit and 64-bit being the
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201most common today). This affects your programs when they attempt to transfer
202numbers in binary format from one CPU architecture to another,
203usually either "live" via network connection, or by storing the
204numbers to secondary storage such as a disk file or tape.
322422de 205
b7df3edc 206Conflicting storage orders make utter mess out of the numbers. If a
d1e3b762 207little-endian host (Intel, VAX) stores 0x12345678 (305419896 in
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208decimal), a big-endian host (Motorola, Sparc, PA) reads it as
2090x78563412 (2018915346 in decimal). Alpha and MIPS can be either:
210Digital/Compaq used/uses them in little-endian mode; SGI/Cray uses
211them in big-endian mode. To avoid this problem in network (socket)
212connections use the C<pack> and C<unpack> formats C<n> and C<N>, the
213"network" orders. These are guaranteed to be portable.
322422de 214
7a4d2905 215As of perl 5.9.2, you can also use the C<E<gt>> and C<E<lt>> modifiers
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216to force big- or little-endian byte-order. This is useful if you want
217to store signed integers or 64-bit integers, for example.
218
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219You can explore the endianness of your platform by unpacking a
220data structure packed in native format such as:
221
222 print unpack("h*", pack("s2", 1, 2)), "\n";
223 # '10002000' on e.g. Intel x86 or Alpha 21064 in little-endian mode
224 # '00100020' on e.g. Motorola 68040
225
226If you need to distinguish between endian architectures you could use
227either of the variables set like so:
228
229 $is_big_endian = unpack("h*", pack("s", 1)) =~ /01/;
4375e838 230 $is_little_endian = unpack("h*", pack("s", 1)) =~ /^1/;
d1e3b762 231
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232Differing widths can cause truncation even between platforms of equal
233endianness. The platform of shorter width loses the upper parts of the
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234number. There is no good solution for this problem except to avoid
235transferring or storing raw binary numbers.
236
b7df3edc 237One can circumnavigate both these problems in two ways. Either
322422de 238transfer and store numbers always in text format, instead of raw
b7df3edc 239binary, or else consider using modules like Data::Dumper (included in
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240the standard distribution as of Perl 5.005) and Storable (included as
241of perl 5.8). Keeping all data as text significantly simplifies matters.
322422de 242
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243The v-strings are portable only up to v2147483647 (0x7FFFFFFF), that's
244how far EBCDIC, or more precisely UTF-EBCDIC will go.
245
433acd8a 246=head2 Files and Filesystems
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247
248Most platforms these days structure files in a hierarchical fashion.
b7df3edc 249So, it is reasonably safe to assume that all platforms support the
6ab3f9cb 250notion of a "path" to uniquely identify a file on the system. How
b7df3edc 251that path is really written, though, differs considerably.
e41182b5 252
4375e838 253Although similar, file path specifications differ between Unix,
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254Windows, S<Mac OS>, OS/2, VMS, VOS, S<RISC OS>, and probably others.
255Unix, for example, is one of the few OSes that has the elegant idea
256of a single root directory.
322422de 257
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258DOS, OS/2, VMS, VOS, and Windows can work similarly to Unix with C</>
259as path separator, or in their own idiosyncratic ways (such as having
260several root directories and various "unrooted" device files such NIL:
261and LPT:).
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262
263S<Mac OS> uses C<:> as a path separator instead of C</>.
264
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265The filesystem may support neither hard links (C<link>) nor
266symbolic links (C<symlink>, C<readlink>, C<lstat>).
433acd8a 267
6ab3f9cb 268The filesystem may support neither access timestamp nor change
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269timestamp (meaning that about the only portable timestamp is the
270modification timestamp), or one second granularity of any timestamps
271(e.g. the FAT filesystem limits the time granularity to two seconds).
272
74555b7a 273The "inode change timestamp" (the C<-C> filetest) may really be the
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274"creation timestamp" (which it is not in UNIX).
275
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276VOS perl can emulate Unix filenames with C</> as path separator. The
277native pathname characters greater-than, less-than, number-sign, and
278percent-sign are always accepted.
279
6ab3f9cb 280S<RISC OS> perl can emulate Unix filenames with C</> as path
322422de 281separator, or go native and use C<.> for path separator and C<:> to
6ab3f9cb 282signal filesystems and disk names.
e41182b5 283
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284Don't assume UNIX filesystem access semantics: that read, write,
285and execute are all the permissions there are, and even if they exist,
286that their semantics (for example what do r, w, and x mean on
287a directory) are the UNIX ones. The various UNIX/POSIX compatibility
288layers usually try to make interfaces like chmod() work, but sometimes
289there simply is no good mapping.
290
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291If all this is intimidating, have no (well, maybe only a little)
292fear. There are modules that can help. The File::Spec modules
293provide methods to do the Right Thing on whatever platform happens
294to be running the program.
e41182b5 295
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296 use File::Spec::Functions;
297 chdir(updir()); # go up one directory
298 $file = catfile(curdir(), 'temp', 'file.txt');
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299 # on Unix and Win32, './temp/file.txt'
300 # on Mac OS, ':temp:file.txt'
d1e3b762 301 # on VMS, '[.temp]file.txt'
e41182b5 302
b7df3edc 303File::Spec is available in the standard distribution as of version
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3045.004_05. File::Spec::Functions is only in File::Spec 0.7 and later,
305and some versions of perl come with version 0.6. If File::Spec
306is not updated to 0.7 or later, you must use the object-oriented
307interface from File::Spec (or upgrade File::Spec).
e41182b5 308
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309In general, production code should not have file paths hardcoded.
310Making them user-supplied or read from a configuration file is
311better, keeping in mind that file path syntax varies on different
312machines.
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313
314This is especially noticeable in scripts like Makefiles and test suites,
315which often assume C</> as a path separator for subdirectories.
316
b7df3edc 317Also of use is File::Basename from the standard distribution, which
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318splits a pathname into pieces (base filename, full path to directory,
319and file suffix).
320
19799a22 321Even when on a single platform (if you can call Unix a single platform),
b7df3edc 322remember not to count on the existence or the contents of particular
3c075c7d 323system-specific files or directories, like F</etc/passwd>,
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324F</etc/sendmail.conf>, F</etc/resolv.conf>, or even F</tmp/>. For
325example, F</etc/passwd> may exist but not contain the encrypted
326passwords, because the system is using some form of enhanced security.
327Or it may not contain all the accounts, because the system is using NIS.
3c075c7d 328If code does need to rely on such a file, include a description of the
b7df3edc 329file and its format in the code's documentation, then make it easy for
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330the user to override the default location of the file.
331
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332Don't assume a text file will end with a newline. They should,
333but people forget.
e41182b5 334
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335Do not have two files or directories of the same name with different
336case, like F<test.pl> and F<Test.pl>, as many platforms have
337case-insensitive (or at least case-forgiving) filenames. Also, try
338not to have non-word characters (except for C<.>) in the names, and
339keep them to the 8.3 convention, for maximum portability, onerous a
340burden though this may appear.
dd9f0070 341
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342Likewise, when using the AutoSplit module, try to keep your functions to
3438.3 naming and case-insensitive conventions; or, at the least,
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344make it so the resulting files have a unique (case-insensitively)
345first 8 characters.
346
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347Whitespace in filenames is tolerated on most systems, but not all,
348and even on systems where it might be tolerated, some utilities
fe829689 349might become confused by such whitespace.
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351Many systems (DOS, VMS ODS-2) cannot have more than one C<.> in their
352filenames.
433acd8a 353
c47ff5f1 354Don't assume C<< > >> won't be the first character of a filename.
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355Always use C<< < >> explicitly to open a file for reading, or even
356better, use the three-arg version of open, unless you want the user to
357be able to specify a pipe open.
0a47030a 358
fe829689 359 open(FILE, '<', $existing_file) or die $!;
0a47030a 360
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361If filenames might use strange characters, it is safest to open it
362with C<sysopen> instead of C<open>. C<open> is magic and can
c47ff5f1 363translate characters like C<< > >>, C<< < >>, and C<|>, which may
b7df3edc 364be the wrong thing to do. (Sometimes, though, it's the right thing.)
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365Three-arg open can also help protect against this translation in cases
366where it is undesirable.
e41182b5 367
ec481373 368Don't use C<:> as a part of a filename since many systems use that for
8939ba94 369their own semantics (Mac OS Classic for separating pathname components,
ec481373 370many networking schemes and utilities for separating the nodename and
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371the pathname, and so on). For the same reasons, avoid C<@>, C<;> and
372C<|>.
ec481373 373
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374Don't assume that in pathnames you can collapse two leading slashes
375C<//> into one: some networking and clustering filesystems have special
376semantics for that. Let the operating system to sort it out.
377
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378The I<portable filename characters> as defined by ANSI C are
379
380 a b c d e f g h i j k l m n o p q r t u v w x y z
381 A B C D E F G H I J K L M N O P Q R T U V W X Y Z
382 0 1 2 3 4 5 6 7 8 9
383 . _ -
384
08fef530 385and the "-" shouldn't be the first character. If you want to be
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386hypercorrect, stay case-insensitive and within the 8.3 naming
387convention (all the files and directories have to be unique within one
388directory if their names are lowercased and truncated to eight
389characters before the C<.>, if any, and to three characters after the
390C<.>, if any). (And do not use C<.>s in directory names.)
ec481373 391
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392=head2 System Interaction
393
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394Not all platforms provide a command line. These are usually platforms
395that rely primarily on a Graphical User Interface (GUI) for user
396interaction. A program requiring a command line interface might
397not work everywhere. This is probably for the user of the program
398to deal with, so don't stay up late worrying about it.
e41182b5 399
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400Some platforms can't delete or rename files held open by the system,
401this limitation may also apply to changing filesystem metainformation
402like file permissions or owners. Remember to C<close> files when you
403are done with them. Don't C<unlink> or C<rename> an open file. Don't
404C<tie> or C<open> a file already tied or opened; C<untie> or C<close>
405it first.
e41182b5 406
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407Don't open the same file more than once at a time for writing, as some
408operating systems put mandatory locks on such files.
409
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410Don't assume that write/modify permission on a directory gives the
411right to add or delete files/directories in that directory. That is
412filesystem specific: in some filesystems you need write/modify
413permission also (or even just) in the file/directory itself. In some
414filesystems (AFS, DFS) the permission to add/delete directory entries
415is a completely separate permission.
416
417Don't assume that a single C<unlink> completely gets rid of the file:
418some filesystems (most notably the ones in VMS) have versioned
419filesystems, and unlink() removes only the most recent one (it doesn't
420remove all the versions because by default the native tools on those
421platforms remove just the most recent version, too). The portable
422idiom to remove all the versions of a file is
423
94bb614c 424 1 while unlink "file";
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425
426This will terminate if the file is undeleteable for some reason
427(protected, not there, and so on).
428
e41182b5 429Don't count on a specific environment variable existing in C<%ENV>.
0a47030a 430Don't count on C<%ENV> entries being case-sensitive, or even
4a0d0822 431case-preserving. Don't try to clear %ENV by saying C<%ENV = ();>, or,
6be8f7a6 432if you really have to, make it conditional on C<$^O ne 'VMS'> since in
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433VMS the C<%ENV> table is much more than a per-process key-value string
434table.
e41182b5 435
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436On VMS, some entries in the %ENV hash are dynamically created when
437their key is used on a read if they did not previously exist. The
438values for C<$ENV{HOME}>, C<$ENV{TERM}>, C<$ENV{HOME}>, and C<$ENV{USER}>,
439are known to be dynamically generated. The specific names that are
440dynamically generated may vary with the version of the C library on VMS,
441and more may exist than is documented.
442
443On VMS by default, changes to the %ENV hash are persistent after the process
444exits. This can cause unintended issues.
445
d1e3b762 446Don't count on signals or C<%SIG> for anything.
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447
448Don't count on filename globbing. Use C<opendir>, C<readdir>, and
449C<closedir> instead.
450
b8099c3d 451Don't count on per-program environment variables, or per-program current
dd9f0070 452directories.
b8099c3d 453
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454Don't count on specific values of C<$!>, neither numeric nor
455especially the strings values-- users may switch their locales causing
456error messages to be translated into their languages. If you can
457trust a POSIXish environment, you can portably use the symbols defined
458by the Errno module, like ENOENT. And don't trust on the values of C<$!>
459at all except immediately after a failed system call.
3c075c7d 460
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461=head2 Command names versus file pathnames
462
463Don't assume that the name used to invoke a command or program with
464C<system> or C<exec> can also be used to test for the existence of the
465file that holds the executable code for that command or program.
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466First, many systems have "internal" commands that are built-in to the
467shell or OS and while these commands can be invoked, there is no
468corresponding file. Second, some operating systems (e.g., Cygwin,
469DJGPP, OS/2, and VOS) have required suffixes for executable files;
470these suffixes are generally permitted on the command name but are not
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471required. Thus, a command like "perl" might exist in a file named
472"perl", "perl.exe", or "perl.pm", depending on the operating system.
473The variable "_exe" in the Config module holds the executable suffix,
68fb0eb7
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474if any. Third, the VMS port carefully sets up $^X and
475$Config{perlpath} so that no further processing is required. This is
476just as well, because the matching regular expression used below would
477then have to deal with a possible trailing version number in the VMS
478file name.
a10d74f3
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479
480To convert $^X to a file pathname, taking account of the requirements
481of the various operating system possibilities, say:
7ee27b7c 482
a10d74f3 483 use Config;
a10d74f3 484 $thisperl = $^X;
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485 if ($^O ne 'VMS')
486 {$thisperl .= $Config{_exe} unless $thisperl =~ m/$Config{_exe}$/i;}
a10d74f3
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487
488To convert $Config{perlpath} to a file pathname, say:
7ee27b7c 489
a10d74f3 490 use Config;
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491 $thisperl = $Config{perlpath};
492 if ($^O ne 'VMS')
493 {$thisperl .= $Config{_exe} unless $thisperl =~ m/$Config{_exe}$/i;}
a10d74f3 494
7137b697
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495=head2 Networking
496
497Don't assume that you can reach the public Internet.
498
499Don't assume that there is only one way to get through firewalls
500to the public Internet.
501
932f293e
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502Don't assume that you can reach outside world through any other port
503than 80, or some web proxy. ftp is blocked by many firewalls.
504
dbc6a9ce
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505Don't assume that you can send email by connecting to the local SMTP port.
506
7137b697 507Don't assume that you can reach yourself or any node by the name
dbc6a9ce 508'localhost'. The same goes for '127.0.0.1'. You will have to try both.
932f293e 509
86feb2c5
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510Don't assume that the host has only one network card, or that it
511can't bind to many virtual IP addresses.
932f293e
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512
513Don't assume a particular network device name.
7137b697 514
dbc6a9ce 515Don't assume a particular set of ioctl()s will work.
7137b697
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516
517Don't assume that you can ping hosts and get replies.
518
dbc6a9ce
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519Don't assume that any particular port (service) will respond.
520
7ee27b7c 521Don't assume that Sys::Hostname (or any other API or command)
dbc6a9ce
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522returns either a fully qualified hostname or a non-qualified hostname:
523it all depends on how the system had been configured. Also remember
524things like DHCP and NAT-- the hostname you get back might not be very
525useful.
526
932f293e
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527All the above "don't":s may look daunting, and they are -- but the key
528is to degrade gracefully if one cannot reach the particular network
529service one wants. Croaking or hanging do not look very professional.
530
e41182b5
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531=head2 Interprocess Communication (IPC)
532
b7df3edc
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533In general, don't directly access the system in code meant to be
534portable. That means, no C<system>, C<exec>, C<fork>, C<pipe>,
535C<``>, C<qx//>, C<open> with a C<|>, nor any of the other things
536that makes being a perl hacker worth being.
e41182b5
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537
538Commands that launch external processes are generally supported on
b7df3edc
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539most platforms (though many of them do not support any type of
540forking). The problem with using them arises from what you invoke
541them on. External tools are often named differently on different
4375e838 542platforms, may not be available in the same location, might accept
b7df3edc
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543different arguments, can behave differently, and often present their
544results in a platform-dependent way. Thus, you should seldom depend
545on them to produce consistent results. (Then again, if you're calling
546I<netstat -a>, you probably don't expect it to run on both Unix and CP/M.)
e41182b5 547
b7df3edc 548One especially common bit of Perl code is opening a pipe to B<sendmail>:
e41182b5 549
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GS
550 open(MAIL, '|/usr/lib/sendmail -t')
551 or die "cannot fork sendmail: $!";
e41182b5
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552
553This is fine for systems programming when sendmail is known to be
554available. But it is not fine for many non-Unix systems, and even
555some Unix systems that may not have sendmail installed. If a portable
b7df3edc
GS
556solution is needed, see the various distributions on CPAN that deal
557with it. Mail::Mailer and Mail::Send in the MailTools distribution are
558commonly used, and provide several mailing methods, including mail,
559sendmail, and direct SMTP (via Net::SMTP) if a mail transfer agent is
560not available. Mail::Sendmail is a standalone module that provides
561simple, platform-independent mailing.
562
563The Unix System V IPC (C<msg*(), sem*(), shm*()>) is not available
564even on all Unix platforms.
e41182b5 565
a81e5e2e
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566Do not use either the bare result of C<pack("N", 10, 20, 30, 40)> or
567bare v-strings (such as C<v10.20.30.40>) to represent IPv4 addresses:
568both forms just pack the four bytes into network order. That this
569would be equal to the C language C<in_addr> struct (which is what the
570socket code internally uses) is not guaranteed. To be portable use
571the routines of the Socket extension, such as C<inet_aton()>,
572C<inet_ntoa()>, and C<sockaddr_in()>.
6b2463a0 573
e41182b5 574The rule of thumb for portable code is: Do it all in portable Perl, or
0a47030a
GS
575use a module (that may internally implement it with platform-specific
576code, but expose a common interface).
e41182b5 577
e41182b5
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578=head2 External Subroutines (XS)
579
b7df3edc 580XS code can usually be made to work with any platform, but dependent
e41182b5
GS
581libraries, header files, etc., might not be readily available or
582portable, or the XS code itself might be platform-specific, just as Perl
583code might be. If the libraries and headers are portable, then it is
584normally reasonable to make sure the XS code is portable, too.
585
b7df3edc
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586A different type of portability issue arises when writing XS code:
587availability of a C compiler on the end-user's system. C brings
588with it its own portability issues, and writing XS code will expose
589you to some of those. Writing purely in Perl is an easier way to
e41182b5
GS
590achieve portability.
591
e41182b5
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592=head2 Standard Modules
593
594In general, the standard modules work across platforms. Notable
6ab3f9cb 595exceptions are the CPAN module (which currently makes connections to external
e41182b5 596programs that may not be available), platform-specific modules (like
6ab3f9cb 597ExtUtils::MM_VMS), and DBM modules.
e41182b5 598
b7df3edc 599There is no one DBM module available on all platforms.
6ab3f9cb
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600SDBM_File and the others are generally available on all Unix and DOSish
601ports, but not in MacPerl, where only NBDM_File and DB_File are
0a47030a 602available.
e41182b5
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603
604The good news is that at least some DBM module should be available, and
6ab3f9cb 605AnyDBM_File will use whichever module it can find. Of course, then
b7df3edc
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606the code needs to be fairly strict, dropping to the greatest common
607factor (e.g., not exceeding 1K for each record), so that it will
6ab3f9cb 608work with any DBM module. See L<AnyDBM_File> for more details.
e41182b5 609
e41182b5
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610=head2 Time and Date
611
0a47030a 612The system's notion of time of day and calendar date is controlled in
b7df3edc 613widely different ways. Don't assume the timezone is stored in C<$ENV{TZ}>,
0a47030a 614and even if it is, don't assume that you can control the timezone through
c87488a3
HS
615that variable. Don't assume anything about the three-letter timezone
616abbreviations (for example that MST would be the Mountain Standard Time,
617it's been known to stand for Moscow Standard Time). If you need to
618use timezones, express them in some unambiguous format like the
619exact number of minutes offset from UTC, or the POSIX timezone
620format.
e41182b5 621
322422de 622Don't assume that the epoch starts at 00:00:00, January 1, 1970,
c87488a3
HS
623because that is OS- and implementation-specific. It is better to
624store a date in an unambiguous representation. The ISO 8601 standard
625defines YYYY-MM-DD as the date format, or YYYY-MM-DDTHH-MM-SS
626(that's a literal "T" separating the date from the time).
627Please do use the ISO 8601 instead of making us to guess what
628date 02/03/04 might be. ISO 8601 even sorts nicely as-is.
629A text representation (like "1987-12-18") can be easily converted
630into an OS-specific value using a module like Date::Parse.
631An array of values, such as those returned by C<localtime>, can be
632converted to an OS-specific representation using Time::Local.
322422de 633
19799a22
GS
634When calculating specific times, such as for tests in time or date modules,
635it may be appropriate to calculate an offset for the epoch.
b7df3edc 636
19799a22
GS
637 require Time::Local;
638 $offset = Time::Local::timegm(0, 0, 0, 1, 0, 70);
b7df3edc 639
19799a22
GS
640The value for C<$offset> in Unix will be C<0>, but in Mac OS will be
641some large number. C<$offset> can then be added to a Unix time value
642to get what should be the proper value on any system.
322422de
GS
643
644=head2 Character sets and character encoding
645
ec481373
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646Assume very little about character sets.
647
648Assume nothing about numerical values (C<ord>, C<chr>) of characters.
649Do not use explicit code point ranges (like \xHH-\xHH); use for
650example symbolic character classes like C<[:print:]>.
651
652Do not assume that the alphabetic characters are encoded contiguously
653(in the numeric sense). There may be gaps.
654
655Do not assume anything about the ordering of the characters.
656The lowercase letters may come before or after the uppercase letters;
b432a672
AL
657the lowercase and uppercase may be interlaced so that both "a" and "A"
658come before "b"; the accented and other international characters may
659be interlaced so that E<auml> comes before "b".
322422de
GS
660
661=head2 Internationalisation
662
b7df3edc
GS
663If you may assume POSIX (a rather large assumption), you may read
664more about the POSIX locale system from L<perllocale>. The locale
665system at least attempts to make things a little bit more portable,
666or at least more convenient and native-friendly for non-English
667users. The system affects character sets and encoding, and date
668and time formatting--amongst other things.
e41182b5 669
c87488a3
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670If you really want to be international, you should consider Unicode.
671See L<perluniintro> and L<perlunicode> for more information.
672
11264fdb
JH
673If you want to use non-ASCII bytes (outside the bytes 0x00..0x7f) in
674the "source code" of your code, to be portable you have to be explicit
675about what bytes they are. Someone might for example be using your
676code under a UTF-8 locale, in which case random native bytes might be
677illegal ("Malformed UTF-8 ...") This means that for example embedding
678ISO 8859-1 bytes beyond 0x7f into your strings might cause trouble
679later. If the bytes are native 8-bit bytes, you can use the C<bytes>
680pragma. If the bytes are in a string (regular expression being a
681curious string), you can often also use the C<\xHH> notation instead
2575c402
JW
682of embedding the bytes as-is. (If you want to write your code in UTF-8,
683you can use the C<utf8>.) The C<bytes> and C<utf8> pragmata are
684available since Perl 5.6.0.
11264fdb 685
e41182b5
GS
686=head2 System Resources
687
0a47030a
GS
688If your code is destined for systems with severely constrained (or
689missing!) virtual memory systems then you want to be I<especially> mindful
690of avoiding wasteful constructs such as:
e41182b5
GS
691
692 # NOTE: this is no longer "bad" in perl5.005
693 for (0..10000000) {} # bad
694 for (my $x = 0; $x <= 10000000; ++$x) {} # good
695
696 @lines = <VERY_LARGE_FILE>; # bad
697
698 while (<FILE>) {$file .= $_} # sometimes bad
0a47030a 699 $file = join('', <FILE>); # better
e41182b5 700
b7df3edc
GS
701The last two constructs may appear unintuitive to most people. The
702first repeatedly grows a string, whereas the second allocates a
703large chunk of memory in one go. On some systems, the second is
704more efficient that the first.
0a47030a 705
e41182b5
GS
706=head2 Security
707
b7df3edc
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708Most multi-user platforms provide basic levels of security, usually
709implemented at the filesystem level. Some, however, do
a1667ba3 710not-- unfortunately. Thus the notion of user id, or "home" directory,
b7df3edc
GS
711or even the state of being logged-in, may be unrecognizable on many
712platforms. If you write programs that are security-conscious, it
713is usually best to know what type of system you will be running
714under so that you can write code explicitly for that platform (or
715class of platforms).
0a47030a 716
a1667ba3
JH
717Don't assume the UNIX filesystem access semantics: the operating
718system or the filesystem may be using some ACL systems, which are
719richer languages than the usual rwx. Even if the rwx exist,
720their semantics might be different.
721
722(From security viewpoint testing for permissions before attempting to
723do something is silly anyway: if one tries this, there is potential
724for race conditions-- someone or something might change the
725permissions between the permissions check and the actual operation.
726Just try the operation.)
727
728Don't assume the UNIX user and group semantics: especially, don't
2edcc0d9 729expect the C<< $< >> and C<< $> >> (or the C<$(> and C<$)>) to work
a1667ba3
JH
730for switching identities (or memberships).
731
732Don't assume set-uid and set-gid semantics. (And even if you do,
733think twice: set-uid and set-gid are a known can of security worms.)
734
e41182b5
GS
735=head2 Style
736
737For those times when it is necessary to have platform-specific code,
738consider keeping the platform-specific code in one place, making porting
6ab3f9cb 739to other platforms easier. Use the Config module and the special
0a47030a
GS
740variable C<$^O> to differentiate platforms, as described in
741L<"PLATFORMS">.
e41182b5 742
b7df3edc
GS
743Be careful in the tests you supply with your module or programs.
744Module code may be fully portable, but its tests might not be. This
745often happens when tests spawn off other processes or call external
746programs to aid in the testing, or when (as noted above) the tests
c87488a3
HS
747assume certain things about the filesystem and paths. Be careful not
748to depend on a specific output style for errors, such as when checking
749C<$!> after a failed system call. Using C<$!> for anything else than
750displaying it as output is doubtful (though see the Errno module for
751testing reasonably portably for error value). Some platforms expect
752a certain output format, and Perl on those platforms may have been
753adjusted accordingly. Most specifically, don't anchor a regex when
754testing an error value.
e41182b5 755
0a47030a 756=head1 CPAN Testers
e41182b5 757
0a47030a
GS
758Modules uploaded to CPAN are tested by a variety of volunteers on
759different platforms. These CPAN testers are notified by mail of each
e41182b5 760new upload, and reply to the list with PASS, FAIL, NA (not applicable to
0a47030a 761this platform), or UNKNOWN (unknown), along with any relevant notations.
e41182b5
GS
762
763The purpose of the testing is twofold: one, to help developers fix any
0a47030a 764problems in their code that crop up because of lack of testing on other
b7df3edc 765platforms; two, to provide users with information about whether
0a47030a 766a given module works on a given platform.
e41182b5 767
7ee27b7c
AT
768Also see:
769
e41182b5
GS
770=over 4
771
7ee27b7c
AT
772=item *
773
774Mailing list: cpan-testers@perl.org
775
776=item *
e41182b5 777
7ee27b7c 778Testing results: http://testers.cpan.org/
e41182b5
GS
779
780=back
781
e41182b5
GS
782=head1 PLATFORMS
783
784As of version 5.002, Perl is built with a C<$^O> variable that
785indicates the operating system it was built on. This was implemented
b7df3edc
GS
786to help speed up code that would otherwise have to C<use Config>
787and use the value of C<$Config{osname}>. Of course, to get more
e41182b5
GS
788detailed information about the system, looking into C<%Config> is
789certainly recommended.
790
b7df3edc
GS
791C<%Config> cannot always be trusted, however, because it was built
792at compile time. If perl was built in one place, then transferred
793elsewhere, some values may be wrong. The values may even have been
794edited after the fact.
6ab3f9cb 795
e41182b5
GS
796=head2 Unix
797
798Perl works on a bewildering variety of Unix and Unix-like platforms (see
799e.g. most of the files in the F<hints/> directory in the source code kit).
800On most of these systems, the value of C<$^O> (hence C<$Config{'osname'}>,
d1e3b762
GS
801too) is determined either by lowercasing and stripping punctuation from the
802first field of the string returned by typing C<uname -a> (or a similar command)
803at the shell prompt or by testing the file system for the presence of
804uniquely named files such as a kernel or header file. Here, for example,
805are a few of the more popular Unix flavors:
e41182b5 806
b7df3edc 807 uname $^O $Config{'archname'}
6ab3f9cb 808 --------------------------------------------
b7df3edc 809 AIX aix aix
6ab3f9cb 810 BSD/OS bsdos i386-bsdos
e1516da7 811 Darwin darwin darwin
6ab3f9cb
GS
812 dgux dgux AViiON-dgux
813 DYNIX/ptx dynixptx i386-dynixptx
b7df3edc 814 FreeBSD freebsd freebsd-i386
df00ff3b 815 Haiku haiku BePC-haiku
d1e3b762 816 Linux linux arm-linux
b7df3edc 817 Linux linux i386-linux
6ab3f9cb
GS
818 Linux linux i586-linux
819 Linux linux ppc-linux
b7df3edc
GS
820 HP-UX hpux PA-RISC1.1
821 IRIX irix irix
b787fad4 822 Mac OS X darwin darwin
d1e3b762
GS
823 NeXT 3 next next-fat
824 NeXT 4 next OPENSTEP-Mach
6ab3f9cb 825 openbsd openbsd i386-openbsd
b7df3edc 826 OSF1 dec_osf alpha-dec_osf
6ab3f9cb
GS
827 reliantunix-n svr4 RM400-svr4
828 SCO_SV sco_sv i386-sco_sv
829 SINIX-N svr4 RM400-svr4
830 sn4609 unicos CRAY_C90-unicos
831 sn6521 unicosmk t3e-unicosmk
832 sn9617 unicos CRAY_J90-unicos
b7df3edc
GS
833 SunOS solaris sun4-solaris
834 SunOS solaris i86pc-solaris
835 SunOS4 sunos sun4-sunos
e41182b5 836
b7df3edc
GS
837Because the value of C<$Config{archname}> may depend on the
838hardware architecture, it can vary more than the value of C<$^O>.
6ab3f9cb 839
e41182b5
GS
840=head2 DOS and Derivatives
841
b7df3edc 842Perl has long been ported to Intel-style microcomputers running under
e41182b5
GS
843systems like PC-DOS, MS-DOS, OS/2, and most Windows platforms you can
844bring yourself to mention (except for Windows CE, if you count that).
b7df3edc 845Users familiar with I<COMMAND.COM> or I<CMD.EXE> style shells should
e41182b5
GS
846be aware that each of these file specifications may have subtle
847differences:
848
849 $filespec0 = "c:/foo/bar/file.txt";
850 $filespec1 = "c:\\foo\\bar\\file.txt";
851 $filespec2 = 'c:\foo\bar\file.txt';
852 $filespec3 = 'c:\\foo\\bar\\file.txt';
853
b7df3edc
GS
854System calls accept either C</> or C<\> as the path separator.
855However, many command-line utilities of DOS vintage treat C</> as
856the option prefix, so may get confused by filenames containing C</>.
857Aside from calling any external programs, C</> will work just fine,
858and probably better, as it is more consistent with popular usage,
859and avoids the problem of remembering what to backwhack and what
860not to.
e41182b5 861
b7df3edc
GS
862The DOS FAT filesystem can accommodate only "8.3" style filenames. Under
863the "case-insensitive, but case-preserving" HPFS (OS/2) and NTFS (NT)
0a47030a 864filesystems you may have to be careful about case returned with functions
e41182b5
GS
865like C<readdir> or used with functions like C<open> or C<opendir>.
866
b7df3edc
GS
867DOS also treats several filenames as special, such as AUX, PRN,
868NUL, CON, COM1, LPT1, LPT2, etc. Unfortunately, sometimes these
869filenames won't even work if you include an explicit directory
870prefix. It is best to avoid such filenames, if you want your code
871to be portable to DOS and its derivatives. It's hard to know what
872these all are, unfortunately.
e41182b5
GS
873
874Users of these operating systems may also wish to make use of
b7df3edc 875scripts such as I<pl2bat.bat> or I<pl2cmd> to
e41182b5
GS
876put wrappers around your scripts.
877
878Newline (C<\n>) is translated as C<\015\012> by STDIO when reading from
6ab3f9cb
GS
879and writing to files (see L<"Newlines">). C<binmode(FILEHANDLE)>
880will keep C<\n> translated as C<\012> for that filehandle. Since it is a
881no-op on other systems, C<binmode> should be used for cross-platform code
b7df3edc
GS
882that deals with binary data. That's assuming you realize in advance
883that your data is in binary. General-purpose programs should
884often assume nothing about their data.
e41182b5 885
b7df3edc 886The C<$^O> variable and the C<$Config{archname}> values for various
e41182b5
GS
887DOSish perls are as follows:
888
67ac489e
MS
889 OS $^O $Config{archname} ID Version
890 --------------------------------------------------------
891 MS-DOS dos ?
892 PC-DOS dos ?
893 OS/2 os2 ?
894 Windows 3.1 ? ? 0 3 01
895 Windows 95 MSWin32 MSWin32-x86 1 4 00
896 Windows 98 MSWin32 MSWin32-x86 1 4 10
897 Windows ME MSWin32 MSWin32-x86 1 ?
898 Windows NT MSWin32 MSWin32-x86 2 4 xx
899 Windows NT MSWin32 MSWin32-ALPHA 2 4 xx
900 Windows NT MSWin32 MSWin32-ppc 2 4 xx
7ee27b7c
AT
901 Windows 2000 MSWin32 MSWin32-x86 2 5 00
902 Windows XP MSWin32 MSWin32-x86 2 5 01
903 Windows 2003 MSWin32 MSWin32-x86 2 5 02
67ac489e 904 Windows CE MSWin32 ? 3
7ee27b7c 905 Cygwin cygwin cygwin
e41182b5 906
34aaaa84
PP
907The various MSWin32 Perl's can distinguish the OS they are running on
908via the value of the fifth element of the list returned from
909Win32::GetOSVersion(). For example:
910
911 if ($^O eq 'MSWin32') {
912 my @os_version_info = Win32::GetOSVersion();
913 print +('3.1','95','NT')[$os_version_info[4]],"\n";
914 }
915
7939d86b
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916There are also Win32::IsWinNT() and Win32::IsWin95(), try C<perldoc Win32>,
917and as of libwin32 0.19 (not part of the core Perl distribution)
918Win32::GetOSName(). The very portable POSIX::uname() will work too:
1d65be3a
JH
919
920 c:\> perl -MPOSIX -we "print join '|', uname"
921 Windows NT|moonru|5.0|Build 2195 (Service Pack 2)|x86
d99f392e 922
e41182b5
GS
923Also see:
924
925=over 4
926
c997b287 927=item *
e41182b5 928
c997b287
GS
929The djgpp environment for DOS, http://www.delorie.com/djgpp/
930and L<perldos>.
e41182b5 931
c997b287 932=item *
e41182b5 933
c997b287 934The EMX environment for DOS, OS/2, etc. emx@iaehv.nl,
f224927c 935ftp://hobbes.nmsu.edu/pub/os2/dev/emx/ Also L<perlos2>.
e41182b5 936
c997b287 937=item *
d1e3b762 938
c997b287
GS
939Build instructions for Win32 in L<perlwin32>, or under the Cygnus environment
940in L<perlcygwin>.
941
942=item *
943
944The C<Win32::*> modules in L<Win32>.
945
946=item *
947
948The ActiveState Pages, http://www.activestate.com/
949
950=item *
951
952The Cygwin environment for Win32; F<README.cygwin> (installed
47dafe4d 953as L<perlcygwin>), http://www.cygwin.com/
c997b287
GS
954
955=item *
956
957The U/WIN environment for Win32,
cea6626f 958http://www.research.att.com/sw/tools/uwin/
c997b287 959
cea6626f 960=item *
d1e3b762 961
cea6626f 962Build instructions for OS/2, L<perlos2>
d1e3b762 963
e41182b5
GS
964=back
965
dd9f0070 966=head2 S<Mac OS>
e41182b5
GS
967
968Any module requiring XS compilation is right out for most people, because
969MacPerl is built using non-free (and non-cheap!) compilers. Some XS
970modules that can work with MacPerl are built and distributed in binary
6ab3f9cb 971form on CPAN.
e41182b5
GS
972
973Directories are specified as:
974
975 volume:folder:file for absolute pathnames
976 volume:folder: for absolute pathnames
977 :folder:file for relative pathnames
978 :folder: for relative pathnames
979 :file for relative pathnames
980 file for relative pathnames
981
b7df3edc 982Files are stored in the directory in alphabetical order. Filenames are
6ab3f9cb 983limited to 31 characters, and may include any character except for
b7df3edc 984null and C<:>, which is reserved as the path separator.
e41182b5 985
0a47030a 986Instead of C<flock>, see C<FSpSetFLock> and C<FSpRstFLock> in the
6ab3f9cb 987Mac::Files module, or C<chmod(0444, ...)> and C<chmod(0666, ...)>.
e41182b5
GS
988
989In the MacPerl application, you can't run a program from the command line;
990programs that expect C<@ARGV> to be populated can be edited with something
991like the following, which brings up a dialog box asking for the command
992line arguments.
993
994 if (!@ARGV) {
995 @ARGV = split /\s+/, MacPerl::Ask('Arguments?');
996 }
997
b7df3edc 998A MacPerl script saved as a "droplet" will populate C<@ARGV> with the full
e41182b5
GS
999pathnames of the files dropped onto the script.
1000
b7df3edc
GS
1001Mac users can run programs under a type of command line interface
1002under MPW (Macintosh Programmer's Workshop, a free development
1003environment from Apple). MacPerl was first introduced as an MPW
1004tool, and MPW can be used like a shell:
e41182b5
GS
1005
1006 perl myscript.plx some arguments
1007
1008ToolServer is another app from Apple that provides access to MPW tools
0a47030a 1009from MPW and the MacPerl app, which allows MacPerl programs to use
e41182b5
GS
1010C<system>, backticks, and piped C<open>.
1011
1012"S<Mac OS>" is the proper name for the operating system, but the value
1013in C<$^O> is "MacOS". To determine architecture, version, or whether
1014the application or MPW tool version is running, check:
1015
1016 $is_app = $MacPerl::Version =~ /App/;
1017 $is_tool = $MacPerl::Version =~ /MPW/;
1018 ($version) = $MacPerl::Version =~ /^(\S+)/;
1019 $is_ppc = $MacPerl::Architecture eq 'MacPPC';
1020 $is_68k = $MacPerl::Architecture eq 'Mac68K';
1021
b787fad4
JH
1022S<Mac OS X>, based on NeXT's OpenStep OS, runs MacPerl natively, under the
1023"Classic" environment. There is no "Carbon" version of MacPerl to run
1024under the primary Mac OS X environment. S<Mac OS X> and its Open Source
1025version, Darwin, both run Unix perl natively.
6ab3f9cb 1026
e41182b5
GS
1027Also see:
1028
1029=over 4
1030
c997b287
GS
1031=item *
1032
862b5365 1033MacPerl Development, http://dev.macperl.org/ .
c997b287
GS
1034
1035=item *
1036
862b5365 1037The MacPerl mailing lists, http://lists.perl.org/ .
e41182b5 1038
7ee27b7c
AT
1039=item *
1040
1041MPW, ftp://ftp.apple.com/developer/Tool_Chest/Core_Mac_OS_Tools/
1042
e41182b5
GS
1043=back
1044
e41182b5
GS
1045=head2 VMS
1046
c997b287 1047Perl on VMS is discussed in L<perlvms> in the perl distribution.
016930a6
JM
1048
1049The official name of VMS as of this writing is OpenVMS.
1050
b7df3edc 1051Perl on VMS can accept either VMS- or Unix-style file
e41182b5
GS
1052specifications as in either of the following:
1053
1054 $ perl -ne "print if /perl_setup/i" SYS$LOGIN:LOGIN.COM
1055 $ perl -ne "print if /perl_setup/i" /sys$login/login.com
1056
1057but not a mixture of both as in:
1058
1059 $ perl -ne "print if /perl_setup/i" sys$login:/login.com
1060 Can't open sys$login:/login.com: file specification syntax error
1061
1062Interacting with Perl from the Digital Command Language (DCL) shell
1063often requires a different set of quotation marks than Unix shells do.
1064For example:
1065
1066 $ perl -e "print ""Hello, world.\n"""
1067 Hello, world.
1068
b7df3edc 1069There are several ways to wrap your perl scripts in DCL F<.COM> files, if
e41182b5
GS
1070you are so inclined. For example:
1071
1072 $ write sys$output "Hello from DCL!"
1073 $ if p1 .eqs. ""
1074 $ then perl -x 'f$environment("PROCEDURE")
1075 $ else perl -x - 'p1 'p2 'p3 'p4 'p5 'p6 'p7 'p8
1076 $ deck/dollars="__END__"
1077 #!/usr/bin/perl
1078
1079 print "Hello from Perl!\n";
1080
1081 __END__
1082 $ endif
1083
1084Do take care with C<$ ASSIGN/nolog/user SYS$COMMAND: SYS$INPUT> if your
c47ff5f1 1085perl-in-DCL script expects to do things like C<< $read = <STDIN>; >>.
e41182b5 1086
016930a6
JM
1087The VMS operating system has two filesystems, known as ODS-2 and ODS-5.
1088
1089For ODS-2, filenames are in the format "name.extension;version". The
1090maximum length for filenames is 39 characters, and the maximum length for
e41182b5
GS
1091extensions is also 39 characters. Version is a number from 1 to
109232767. Valid characters are C</[A-Z0-9$_-]/>.
1093
016930a6
JM
1094The ODS-2 filesystem is case-insensitive and does not preserve case.
1095Perl simulates this by converting all filenames to lowercase internally.
1096
1097For ODS-5, filenames may have almost any character in them and can include
1098Unicode characters. Characters that could be misinterpreted by the DCL
1099shell or file parsing utilities need to be prefixed with the C<^>
1100character, or replaced with hexadecimal characters prefixed with the
1101C<^> character. Such prefixing is only needed with the pathnames are
1102in VMS format in applications. Programs that can accept the UNIX format
1103of pathnames do not need the escape characters. The maximum length for
1104filenames is 255 characters. The ODS-5 file system can handle both
1105a case preserved and a case sensitive mode.
1106
1107ODS-5 is only available on the OpenVMS for 64 bit platforms.
1108
1109Support for the extended file specifications is being done as optional
1110settings to preserve backward compatibility with Perl scripts that
1111assume the previous VMS limitations.
1112
1113In general routines on VMS that get a UNIX format file specification
1114should return it in a UNIX format, and when they get a VMS format
1115specification they should return a VMS format unless they are documented
1116to do a conversion.
1117
1118For routines that generate return a file specification, VMS allows setting
1119if the C library which Perl is built on if it will be returned in VMS
1120format or in UNIX format.
1121
1122With the ODS-2 file system, there is not much difference in syntax of
1123filenames without paths for VMS or UNIX. With the extended character
1124set available with ODS-5 there can be a significant difference.
1125
1126Because of this, existing Perl scripts written for VMS were sometimes
1127treating VMS and UNIX filenames interchangeably. Without the extended
1128character set enabled, this behavior will mostly be maintained for
1129backwards compatibility.
1130
1131When extended characters are enabled with ODS-5, the handling of
1132UNIX formatted file specifications is to that of a UNIX system.
1133
1134VMS file specifications without extensions have a trailing dot. An
1135equivalent UNIX file specification should not show the trailing dot.
1136
1137The result of all of this, is that for VMS, for portable scripts, you
1138can not depend on Perl to present the filenames in lowercase, to be
1139case sensitive, and that the filenames could be returned in either
1140UNIX or VMS format.
1141
1142And if a routine returns a file specification, unless it is intended to
1143convert it, it should return it in the same format as it found it.
1144
1145C<readdir> by default has traditionally returned lowercased filenames.
1146When the ODS-5 support is enabled, it will return the exact case of the
1147filename on the disk.
1148
1149Files without extensions have a trailing period on them, so doing a
1150C<readdir> in the default mode with a file named F<A.;5> will
1151return F<a.> when VMS is (though that file could be opened with
0a47030a 1152C<open(FH, 'A')>).
e41182b5 1153
016930a6
JM
1154With support for extended file specifications and if C<opendir> was
1155given a UNIX format directory, a file named F<A.;5> will return F<a>
1156and optionally in the exact case on the disk. When C<opendir> is given
1157a VMS format directory, then C<readdir> should return F<a.>, and
1158again with the optionally the exact case.
1159
f34d0673 1160RMS had an eight level limit on directory depths from any rooted logical
1089a9e3
CB
1161(allowing 16 levels overall) prior to VMS 7.2, and even with versions of
1162VMS on VAX up through 7.3. Hence C<PERL_ROOT:[LIB.2.3.4.5.6.7.8]> is a
1163valid directory specification but C<PERL_ROOT:[LIB.2.3.4.5.6.7.8.9]> is
1164not. F<Makefile.PL> authors might have to take this into account, but at
1165least they can refer to the former as C</PERL_ROOT/lib/2/3/4/5/6/7/8/>.
1166
1167Pumpkings and module integrators can easily see whether files with too many
1168directory levels have snuck into the core by running the following in the
1169top-level source directory:
1170
1171 $ perl -ne "$_=~s/\s+.*//; print if scalar(split /\//) > 8;" < MANIFEST
1172
e41182b5 1173
6ab3f9cb 1174The VMS::Filespec module, which gets installed as part of the build
0a47030a
GS
1175process on VMS, is a pure Perl module that can easily be installed on
1176non-VMS platforms and can be helpful for conversions to and from RMS
016930a6
JM
1177native formats. It is also now the only way that you should check to
1178see if VMS is in a case sensitive mode.
e41182b5 1179
5e12dbfa
PP
1180What C<\n> represents depends on the type of file opened. It usually
1181represents C<\012> but it could also be C<\015>, C<\012>, C<\015\012>,
fa11829f 1182C<\000>, C<\040>, or nothing depending on the file organization and
5e12dbfa
PP
1183record format. The VMS::Stdio module provides access to the
1184special fopen() requirements of files with unusual attributes on VMS.
e41182b5
GS
1185
1186TCP/IP stacks are optional on VMS, so socket routines might not be
1187implemented. UDP sockets may not be supported.
1188
016930a6
JM
1189The TCP/IP library support for all current versions of VMS is dynamically
1190loaded if present, so even if the routines are configured, they may
1191return a status indicating that they are not implemented.
1192
e41182b5
GS
1193The value of C<$^O> on OpenVMS is "VMS". To determine the architecture
1194that you are running on without resorting to loading all of C<%Config>
1195you can examine the content of the C<@INC> array like so:
1196
1197 if (grep(/VMS_AXP/, @INC)) {
1198 print "I'm on Alpha!\n";
6ab3f9cb 1199
e41182b5
GS
1200 } elsif (grep(/VMS_VAX/, @INC)) {
1201 print "I'm on VAX!\n";
6ab3f9cb 1202
016930a6
JM
1203 } elsif (grep(/VMS_IA64/, @INC)) {
1204 print "I'm on IA64!\n";
1205
e41182b5
GS
1206 } else {
1207 print "I'm not so sure about where $^O is...\n";
1208 }
1209
016930a6
JM
1210In general, the significant differences should only be if Perl is running
1211on VMS_VAX or one of the 64 bit OpenVMS platforms.
1212
b7df3edc
GS
1213On VMS, perl determines the UTC offset from the C<SYS$TIMEZONE_DIFFERENTIAL>
1214logical name. Although the VMS epoch began at 17-NOV-1858 00:00:00.00,
6ab3f9cb 1215calls to C<localtime> are adjusted to count offsets from
b7df3edc 121601-JAN-1970 00:00:00.00, just like Unix.
6ab3f9cb 1217
e41182b5
GS
1218Also see:
1219
1220=over 4
1221
c997b287
GS
1222=item *
1223
1224F<README.vms> (installed as L<README_vms>), L<perlvms>
1225
1226=item *
1227
1089a9e3 1228vmsperl list, vmsperl-subscribe@perl.org
e41182b5 1229
c997b287 1230=item *
e41182b5 1231
c997b287 1232vmsperl on the web, http://www.sidhe.org/vmsperl/index.html
e41182b5
GS
1233
1234=back
1235
495c5fdc
GP
1236=head2 VOS
1237
9a997319
JH
1238Perl on VOS is discussed in F<README.vos> in the perl distribution
1239(installed as L<perlvos>). Perl on VOS can accept either VOS- or
1240Unix-style file specifications as in either of the following:
495c5fdc 1241
ea8b8ad2
VP
1242 $ perl -ne "print if /perl_setup/i" >system>notices
1243 $ perl -ne "print if /perl_setup/i" /system/notices
495c5fdc
GP
1244
1245or even a mixture of both as in:
1246
ea8b8ad2 1247 $ perl -ne "print if /perl_setup/i" >system/notices
495c5fdc 1248
b7df3edc 1249Even though VOS allows the slash character to appear in object
495c5fdc
GP
1250names, because the VOS port of Perl interprets it as a pathname
1251delimiting character, VOS files, directories, or links whose names
1252contain a slash character cannot be processed. Such files must be
a3dfe201 1253renamed before they can be processed by Perl. Note that VOS limits
b449fc5b
NC
1254file names to 32 or fewer characters, file names cannot start with a
1255C<-> character, or contain any character matching C<< tr/ !%&'()*+;<>?// >>
495c5fdc 1256
495c5fdc
GP
1257The value of C<$^O> on VOS is "VOS". To determine the architecture that
1258you are running on without resorting to loading all of C<%Config> you
c997b287 1259can examine the content of the @INC array like so:
495c5fdc 1260
24e8e380 1261 if ($^O =~ /VOS/) {
495c5fdc
GP
1262 print "I'm on a Stratus box!\n";
1263 } else {
1264 print "I'm not on a Stratus box!\n";
1265 die;
1266 }
1267
495c5fdc
GP
1268Also see:
1269
1270=over 4
1271
c997b287 1272=item *
495c5fdc 1273
cc07ed0b 1274F<README.vos> (installed as L<perlvos>)
c997b287
GS
1275
1276=item *
1277
1278The VOS mailing list.
495c5fdc
GP
1279
1280There is no specific mailing list for Perl on VOS. You can post
1281comments to the comp.sys.stratus newsgroup, or subscribe to the general
cc07ed0b 1282Stratus mailing list. Send a letter with "subscribe Info-Stratus" in
495c5fdc
GP
1283the message body to majordomo@list.stratagy.com.
1284
c997b287
GS
1285=item *
1286
cc07ed0b 1287VOS Perl on the web at http://ftp.stratus.com/pub/vos/posix/posix.html
495c5fdc
GP
1288
1289=back
1290
e41182b5
GS
1291=head2 EBCDIC Platforms
1292
1293Recent versions of Perl have been ported to platforms such as OS/400 on
d1e3b762
GS
1294AS/400 minicomputers as well as OS/390, VM/ESA, and BS2000 for S/390
1295Mainframes. Such computers use EBCDIC character sets internally (usually
0cc436d0
GS
1296Character Code Set ID 0037 for OS/400 and either 1047 or POSIX-BC for S/390
1297systems). On the mainframe perl currently works under the "Unix system
1298services for OS/390" (formerly known as OpenEdition), VM/ESA OpenEdition, or
1299the BS200 POSIX-BC system (BS2000 is supported in perl 5.6 and greater).
522b859a
JH
1300See L<perlos390> for details. Note that for OS/400 there is also a port of
1301Perl 5.8.1/5.9.0 or later to the PASE which is ASCII-based (as opposed to
1302ILE which is EBCDIC-based), see L<perlos400>.
e41182b5 1303
7c5ffed3
JH
1304As of R2.5 of USS for OS/390 and Version 2.3 of VM/ESA these Unix
1305sub-systems do not support the C<#!> shebang trick for script invocation.
1306Hence, on OS/390 and VM/ESA perl scripts can be executed with a header
1307similar to the following simple script:
e41182b5
GS
1308
1309 : # use perl
1310 eval 'exec /usr/local/bin/perl -S $0 ${1+"$@"}'
1311 if 0;
1312 #!/usr/local/bin/perl # just a comment really
1313
1314 print "Hello from perl!\n";
1315
d1e3b762
GS
1316OS/390 will support the C<#!> shebang trick in release 2.8 and beyond.
1317Calls to C<system> and backticks can use POSIX shell syntax on all
1318S/390 systems.
1319
b7df3edc 1320On the AS/400, if PERL5 is in your library list, you may need
6ab3f9cb
GS
1321to wrap your perl scripts in a CL procedure to invoke them like so:
1322
1323 BEGIN
1324 CALL PGM(PERL5/PERL) PARM('/QOpenSys/hello.pl')
1325 ENDPGM
1326
1327This will invoke the perl script F<hello.pl> in the root of the
1328QOpenSys file system. On the AS/400 calls to C<system> or backticks
1329must use CL syntax.
1330
e41182b5 1331On these platforms, bear in mind that the EBCDIC character set may have
0a47030a
GS
1332an effect on what happens with some perl functions (such as C<chr>,
1333C<pack>, C<print>, C<printf>, C<ord>, C<sort>, C<sprintf>, C<unpack>), as
1334well as bit-fiddling with ASCII constants using operators like C<^>, C<&>
1335and C<|>, not to mention dealing with socket interfaces to ASCII computers
6ab3f9cb 1336(see L<"Newlines">).
e41182b5 1337
b7df3edc
GS
1338Fortunately, most web servers for the mainframe will correctly
1339translate the C<\n> in the following statement to its ASCII equivalent
1340(C<\r> is the same under both Unix and OS/390 & VM/ESA):
e41182b5
GS
1341
1342 print "Content-type: text/html\r\n\r\n";
1343
d1e3b762 1344The values of C<$^O> on some of these platforms includes:
e41182b5 1345
d1e3b762
GS
1346 uname $^O $Config{'archname'}
1347 --------------------------------------------
1348 OS/390 os390 os390
1349 OS400 os400 os400
1350 POSIX-BC posix-bc BS2000-posix-bc
1351 VM/ESA vmesa vmesa
3c075c7d 1352
e41182b5
GS
1353Some simple tricks for determining if you are running on an EBCDIC
1354platform could include any of the following (perhaps all):
1355
1356 if ("\t" eq "\05") { print "EBCDIC may be spoken here!\n"; }
1357
1358 if (ord('A') == 193) { print "EBCDIC may be spoken here!\n"; }
1359
1360 if (chr(169) eq 'z') { print "EBCDIC may be spoken here!\n"; }
1361
b7df3edc 1362One thing you may not want to rely on is the EBCDIC encoding
0a47030a
GS
1363of punctuation characters since these may differ from code page to code
1364page (and once your module or script is rumoured to work with EBCDIC,
1365folks will want it to work with all EBCDIC character sets).
e41182b5
GS
1366
1367Also see:
1368
1369=over 4
1370
c997b287
GS
1371=item *
1372
dc5c060f 1373L<perlos390>, F<README.os390>, F<perlbs2000>, F<README.vmesa>,
bb462878 1374L<perlebcdic>.
c997b287
GS
1375
1376=item *
e41182b5
GS
1377
1378The perl-mvs@perl.org list is for discussion of porting issues as well as
1379general usage issues for all EBCDIC Perls. Send a message body of
1380"subscribe perl-mvs" to majordomo@perl.org.
1381
7ee27b7c 1382=item *
c997b287
GS
1383
1384AS/400 Perl information at
b1866b2d 1385http://as400.rochester.ibm.com/
d1e3b762 1386as well as on CPAN in the F<ports/> directory.
e41182b5
GS
1387
1388=back
1389
b8099c3d
CN
1390=head2 Acorn RISC OS
1391
b7df3edc
GS
1392Because Acorns use ASCII with newlines (C<\n>) in text files as C<\012> like
1393Unix, and because Unix filename emulation is turned on by default,
1394most simple scripts will probably work "out of the box". The native
6ab3f9cb 1395filesystem is modular, and individual filesystems are free to be
0a47030a 1396case-sensitive or insensitive, and are usually case-preserving. Some
b7df3edc 1397native filesystems have name length limits, which file and directory
6ab3f9cb
GS
1398names are silently truncated to fit. Scripts should be aware that the
1399standard filesystem currently has a name length limit of B<10>
1400characters, with up to 77 items in a directory, but other filesystems
0a47030a 1401may not impose such limitations.
b8099c3d
CN
1402
1403Native filenames are of the form
1404
6ab3f9cb 1405 Filesystem#Special_Field::DiskName.$.Directory.Directory.File
dd9f0070 1406
b8099c3d
CN
1407where
1408
1409 Special_Field is not usually present, but may contain . and $ .
1410 Filesystem =~ m|[A-Za-z0-9_]|
1411 DsicName =~ m|[A-Za-z0-9_/]|
1412 $ represents the root directory
1413 . is the path separator
1414 @ is the current directory (per filesystem but machine global)
1415 ^ is the parent directory
1416 Directory and File =~ m|[^\0- "\.\$\%\&:\@\\^\|\177]+|
1417
1418The default filename translation is roughly C<tr|/.|./|;>
1419
6ab3f9cb 1420Note that C<"ADFS::HardDisk.$.File" ne 'ADFS::HardDisk.$.File'> and that
0a47030a
GS
1421the second stage of C<$> interpolation in regular expressions will fall
1422foul of the C<$.> if scripts are not careful.
1423
1424Logical paths specified by system variables containing comma-separated
b7df3edc 1425search lists are also allowed; hence C<System:Modules> is a valid
0a47030a 1426filename, and the filesystem will prefix C<Modules> with each section of
6ab3f9cb 1427C<System$Path> until a name is made that points to an object on disk.
b7df3edc 1428Writing to a new file C<System:Modules> would be allowed only if
0a47030a
GS
1429C<System$Path> contains a single item list. The filesystem will also
1430expand system variables in filenames if enclosed in angle brackets, so
c47ff5f1 1431C<< <System$Dir>.Modules >> would look for the file
0a47030a 1432S<C<$ENV{'System$Dir'} . 'Modules'>>. The obvious implication of this is
c47ff5f1 1433that B<fully qualified filenames can start with C<< <> >>> and should
0a47030a 1434be protected when C<open> is used for input.
b8099c3d
CN
1435
1436Because C<.> was in use as a directory separator and filenames could not
1437be assumed to be unique after 10 characters, Acorn implemented the C
1438compiler to strip the trailing C<.c> C<.h> C<.s> and C<.o> suffix from
1439filenames specified in source code and store the respective files in
b7df3edc 1440subdirectories named after the suffix. Hence files are translated:
b8099c3d
CN
1441
1442 foo.h h.foo
1443 C:foo.h C:h.foo (logical path variable)
1444 sys/os.h sys.h.os (C compiler groks Unix-speak)
1445 10charname.c c.10charname
1446 10charname.o o.10charname
1447 11charname_.c c.11charname (assuming filesystem truncates at 10)
1448
1449The Unix emulation library's translation of filenames to native assumes
b7df3edc
GS
1450that this sort of translation is required, and it allows a user-defined list
1451of known suffixes that it will transpose in this fashion. This may
1452seem transparent, but consider that with these rules C<foo/bar/baz.h>
0a47030a
GS
1453and C<foo/bar/h/baz> both map to C<foo.bar.h.baz>, and that C<readdir> and
1454C<glob> cannot and do not attempt to emulate the reverse mapping. Other
6ab3f9cb 1455C<.>'s in filenames are translated to C</>.
0a47030a 1456
b7df3edc 1457As implied above, the environment accessed through C<%ENV> is global, and
0a47030a 1458the convention is that program specific environment variables are of the
6ab3f9cb
GS
1459form C<Program$Name>. Each filesystem maintains a current directory,
1460and the current filesystem's current directory is the B<global> current
b7df3edc
GS
1461directory. Consequently, sociable programs don't change the current
1462directory but rely on full pathnames, and programs (and Makefiles) cannot
0a47030a
GS
1463assume that they can spawn a child process which can change the current
1464directory without affecting its parent (and everyone else for that
1465matter).
1466
b7df3edc
GS
1467Because native operating system filehandles are global and are currently
1468allocated down from 255, with 0 being a reserved value, the Unix emulation
0a47030a
GS
1469library emulates Unix filehandles. Consequently, you can't rely on
1470passing C<STDIN>, C<STDOUT>, or C<STDERR> to your children.
1471
1472The desire of users to express filenames of the form
c47ff5f1 1473C<< <Foo$Dir>.Bar >> on the command line unquoted causes problems,
0a47030a 1474too: C<``> command output capture has to perform a guessing game. It
c47ff5f1 1475assumes that a string C<< <[^<>]+\$[^<>]> >> is a
0a47030a 1476reference to an environment variable, whereas anything else involving
c47ff5f1 1477C<< < >> or C<< > >> is redirection, and generally manages to be 99%
0a47030a
GS
1478right. Of course, the problem remains that scripts cannot rely on any
1479Unix tools being available, or that any tools found have Unix-like command
1480line arguments.
1481
b7df3edc
GS
1482Extensions and XS are, in theory, buildable by anyone using free
1483tools. In practice, many don't, as users of the Acorn platform are
1484used to binary distributions. MakeMaker does run, but no available
1485make currently copes with MakeMaker's makefiles; even if and when
1486this should be fixed, the lack of a Unix-like shell will cause
1487problems with makefile rules, especially lines of the form C<cd
1488sdbm && make all>, and anything using quoting.
b8099c3d
CN
1489
1490"S<RISC OS>" is the proper name for the operating system, but the value
1491in C<$^O> is "riscos" (because we don't like shouting).
1492
e41182b5
GS
1493=head2 Other perls
1494
b7df3edc 1495Perl has been ported to many platforms that do not fit into any of
cd86ed9d
JV
1496the categories listed above. Some, such as AmigaOS, BeOS, HP MPE/iX,
1497QNX, Plan 9, and VOS, have been well-integrated into the standard
1498Perl source code kit. You may need to see the F<ports/> directory
1499on CPAN for information, and possibly binaries, for the likes of:
1500aos, Atari ST, lynxos, riscos, Novell Netware, Tandem Guardian,
1501I<etc.> (Yes, we know that some of these OSes may fall under the
1502Unix category, but we are not a standards body.)
e41182b5 1503
d1e3b762
GS
1504Some approximate operating system names and their C<$^O> values
1505in the "OTHER" category include:
1506
1507 OS $^O $Config{'archname'}
1508 ------------------------------------------
1509 Amiga DOS amigaos m68k-amigos
cec2c193 1510 BeOS beos
d1e3b762
GS
1511 MPE/iX mpeix PA-RISC1.1
1512
e41182b5
GS
1513See also:
1514
1515=over 4
1516
c997b287
GS
1517=item *
1518
1519Amiga, F<README.amiga> (installed as L<perlamiga>).
1520
1521=item *
d1e3b762 1522
c997b287 1523Be OS, F<README.beos>
e41182b5 1524
c997b287
GS
1525=item *
1526
1527HP 300 MPE/iX, F<README.mpeix> and Mark Bixby's web page
e59066d8 1528http://www.bixby.org/mark/porting.html
c997b287
GS
1529
1530=item *
e41182b5 1531
6ab3f9cb 1532A free perl5-based PERL.NLM for Novell Netware is available in
c997b287 1533precompiled binary and source code form from http://www.novell.com/
6ab3f9cb 1534as well as from CPAN.
e41182b5 1535
13a2d996 1536=item *
c997b287 1537
e6f03d26 1538S<Plan 9>, F<README.plan9>
d1e3b762 1539
e41182b5
GS
1540=back
1541
e41182b5
GS
1542=head1 FUNCTION IMPLEMENTATIONS
1543
b7df3edc
GS
1544Listed below are functions that are either completely unimplemented
1545or else have been implemented differently on various platforms.
1546Following each description will be, in parentheses, a list of
1547platforms that the description applies to.
e41182b5 1548
b7df3edc
GS
1549The list may well be incomplete, or even wrong in some places. When
1550in doubt, consult the platform-specific README files in the Perl
1551source distribution, and any other documentation resources accompanying
1552a given port.
e41182b5 1553
0a47030a 1554Be aware, moreover, that even among Unix-ish systems there are variations.
e41182b5 1555
b7df3edc
GS
1556For many functions, you can also query C<%Config>, exported by
1557default from the Config module. For example, to check whether the
1558platform has the C<lstat> call, check C<$Config{d_lstat}>. See
1559L<Config> for a full description of available variables.
e41182b5
GS
1560
1561=head2 Alphabetical Listing of Perl Functions
1562
1563=over 8
1564
e41182b5
GS
1565=item -X
1566
b7df3edc 1567C<-r>, C<-w>, and C<-x> have a limited meaning only; directories
e41182b5 1568and applications are executable, and there are no uid/gid
b7df3edc 1569considerations. C<-o> is not supported. (S<Mac OS>)
e41182b5 1570
038ae9a4
SH
1571C<-w> only inspects the read-only file attribute (FILE_ATTRIBUTE_READONLY),
1572which determines whether the directory can be deleted, not whether it can
1573be written to. Directories always have read and write access unless denied
1574by discretionary access control lists (DACLs). (S<Win32>)
1575
b7df3edc
GS
1576C<-r>, C<-w>, C<-x>, and C<-o> tell whether the file is accessible,
1577which may not reflect UIC-based file protections. (VMS)
e41182b5 1578
b8099c3d
CN
1579C<-s> returns the size of the data fork, not the total size of data fork
1580plus resource fork. (S<Mac OS>).
1581
1582C<-s> by name on an open file will return the space reserved on disk,
1583rather than the current extent. C<-s> on an open filehandle returns the
b7df3edc 1584current size. (S<RISC OS>)
b8099c3d 1585
e41182b5 1586C<-R>, C<-W>, C<-X>, C<-O> are indistinguishable from C<-r>, C<-w>,
b8099c3d 1587C<-x>, C<-o>. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5
GS
1588
1589C<-b>, C<-c>, C<-k>, C<-g>, C<-p>, C<-u>, C<-A> are not implemented.
1590(S<Mac OS>)
1591
287a962e 1592C<-g>, C<-k>, C<-l>, C<-u>, C<-A> are not particularly meaningful.
b8099c3d 1593(Win32, VMS, S<RISC OS>)
e41182b5 1594
287a962e
JD
1595C<-p> is not particularly meaningful. (VMS, S<RISC OS>)
1596
e41182b5
GS
1597C<-d> is true if passed a device spec without an explicit directory.
1598(VMS)
1599
1600C<-T> and C<-B> are implemented, but might misclassify Mac text files
0a47030a 1601with foreign characters; this is the case will all platforms, but may
b7df3edc 1602affect S<Mac OS> often. (S<Mac OS>)
e41182b5
GS
1603
1604C<-x> (or C<-X>) determine if a file ends in one of the executable
b7df3edc 1605suffixes. C<-S> is meaningless. (Win32)
e41182b5 1606
b8099c3d
CN
1607C<-x> (or C<-X>) determine if a file has an executable file type.
1608(S<RISC OS>)
1609
47cd99a4 1610=item atan2
519bc777
RGS
1611
1612Due to issues with various CPUs, math libraries, compilers, and standards,
1613results for C<atan2()> may vary depending on any combination of the above.
1614Perl attempts to conform to the Open Group/IEEE standards for the results
1615returned from C<atan2()>, but cannot force the issue if the system Perl is
1616run on does not allow it. (Tru64, HP-UX 10.20)
1617
1618The current version of the standards for C<atan2()> is available at
1619L<http://www.opengroup.org/onlinepubs/009695399/functions/atan2.html>.
1620
47cd99a4 1621=item binmode
e41182b5 1622
b7df3edc 1623Meaningless. (S<Mac OS>, S<RISC OS>)
e41182b5
GS
1624
1625Reopens file and restores pointer; if function fails, underlying
1626filehandle may be closed, or pointer may be in a different position.
1627(VMS)
1628
1629The value returned by C<tell> may be affected after the call, and
1630the filehandle may be flushed. (Win32)
1631
47cd99a4 1632=item chmod
e41182b5 1633
b7df3edc 1634Only limited meaning. Disabling/enabling write permission is mapped to
e41182b5
GS
1635locking/unlocking the file. (S<Mac OS>)
1636
1637Only good for changing "owner" read-write access, "group", and "other"
1638bits are meaningless. (Win32)
1639
b8099c3d
CN
1640Only good for changing "owner" and "other" read-write access. (S<RISC OS>)
1641
495c5fdc
GP
1642Access permissions are mapped onto VOS access-control list changes. (VOS)
1643
4e51f8e4 1644The actual permissions set depend on the value of the C<CYGWIN>
789f0d36 1645in the SYSTEM environment settings. (Cygwin)
4e51f8e4 1646
47cd99a4 1647=item chown
e41182b5 1648
3fd80bd6 1649Not implemented. (S<Mac OS>, Win32, S<Plan 9>, S<RISC OS>)
e41182b5
GS
1650
1651Does nothing, but won't fail. (Win32)
1652
3fd80bd6
PG
1653A little funky, because VOS's notion of ownership is a little funky (VOS).
1654
e41182b5
GS
1655=item chroot
1656
e6f03d26 1657Not implemented. (S<Mac OS>, Win32, VMS, S<Plan 9>, S<RISC OS>, VOS, VM/ESA)
e41182b5 1658
47cd99a4 1659=item crypt
e41182b5
GS
1660
1661May not be available if library or source was not provided when building
b8099c3d 1662perl. (Win32)
e41182b5 1663
47cd99a4 1664=item dbmclose
e41182b5 1665
e6f03d26 1666Not implemented. (VMS, S<Plan 9>, VOS)
e41182b5 1667
47cd99a4 1668=item dbmopen
e41182b5 1669
e6f03d26 1670Not implemented. (VMS, S<Plan 9>, VOS)
e41182b5 1671
47cd99a4 1672=item dump
e41182b5 1673
b8099c3d 1674Not useful. (S<Mac OS>, S<RISC OS>)
e41182b5 1675
84d78eb7 1676Not supported. (Cygwin, Win32)
e41182b5 1677
b8099c3d 1678Invokes VMS debugger. (VMS)
e41182b5 1679
47cd99a4 1680=item exec
e41182b5
GS
1681
1682Not implemented. (S<Mac OS>)
1683
7c5ffed3 1684Implemented via Spawn. (VM/ESA)
3c075c7d 1685
0f897271
GS
1686Does not automatically flush output handles on some platforms.
1687(SunOS, Solaris, HP-UX)
1688
fe12c0e8
MS
1689=item exit
1690
1691Emulates UNIX exit() (which considers C<exit 1> to indicate an error) by
1692mapping the C<1> to SS$_ABORT (C<44>). This behavior may be overridden
1693with the pragma C<use vmsish 'exit'>. As with the CRTL's exit()
1694function, C<exit 0> is also mapped to an exit status of SS$_NORMAL
1695(C<1>); this mapping cannot be overridden. Any other argument to exit()
016930a6
JM
1696is used directly as Perl's exit status. On VMS, unless the future
1697POSIX_EXIT mode is enabled, the exit code should always be a valid
1698VMS exit code and not a generic number. When the POSIX_EXIT mode is
1699enabled, a generic number will be encoded in a method compatible with
1700the C library _POSIX_EXIT macro so that it can be decoded by other
1701programs, particularly ones written in C, like the GNV package. (VMS)
fe12c0e8 1702
47cd99a4 1703=item fcntl
e41182b5 1704
016930a6
JM
1705Not implemented. (Win32)
1706Some functions available based on the version of VMS. (VMS)
e41182b5 1707
47cd99a4 1708=item flock
e41182b5 1709
495c5fdc 1710Not implemented (S<Mac OS>, VMS, S<RISC OS>, VOS).
e41182b5
GS
1711
1712Available only on Windows NT (not on Windows 95). (Win32)
1713
1714=item fork
1715
3fd80bd6 1716Not implemented. (S<Mac OS>, AmigaOS, S<RISC OS>, VM/ESA, VMS)
0f897271
GS
1717
1718Emulated using multiple interpreters. See L<perlfork>. (Win32)
1719
1720Does not automatically flush output handles on some platforms.
1721(SunOS, Solaris, HP-UX)
e41182b5
GS
1722
1723=item getlogin
1724
b8099c3d 1725Not implemented. (S<Mac OS>, S<RISC OS>)
e41182b5 1726
47cd99a4 1727=item getpgrp
e41182b5 1728
3fd80bd6 1729Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5
GS
1730
1731=item getppid
1732
41cbbefa 1733Not implemented. (S<Mac OS>, Win32, S<RISC OS>)
e41182b5 1734
47cd99a4 1735=item getpriority
e41182b5 1736
7c5ffed3 1737Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
e41182b5 1738
47cd99a4 1739=item getpwnam
e41182b5
GS
1740
1741Not implemented. (S<Mac OS>, Win32)
1742
b8099c3d
CN
1743Not useful. (S<RISC OS>)
1744
47cd99a4 1745=item getgrnam
e41182b5 1746
b8099c3d 1747Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5 1748
47cd99a4 1749=item getnetbyname
e41182b5 1750
e6f03d26 1751Not implemented. (S<Mac OS>, Win32, S<Plan 9>)
e41182b5 1752
47cd99a4 1753=item getpwuid
e41182b5
GS
1754
1755Not implemented. (S<Mac OS>, Win32)
1756
b8099c3d
CN
1757Not useful. (S<RISC OS>)
1758
47cd99a4 1759=item getgrgid
e41182b5 1760
b8099c3d 1761Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5 1762
47cd99a4 1763=item getnetbyaddr
e41182b5 1764
e6f03d26 1765Not implemented. (S<Mac OS>, Win32, S<Plan 9>)
e41182b5 1766
47cd99a4 1767=item getprotobynumber
e41182b5
GS
1768
1769Not implemented. (S<Mac OS>)
1770
47cd99a4 1771=item getservbyport
e41182b5
GS
1772
1773Not implemented. (S<Mac OS>)
1774
1775=item getpwent
1776
7c5ffed3 1777Not implemented. (S<Mac OS>, Win32, VM/ESA)
e41182b5
GS
1778
1779=item getgrent
1780
7c5ffed3 1781Not implemented. (S<Mac OS>, Win32, VMS, VM/ESA)
e41182b5 1782
ef5a6dd7
JH
1783=item gethostbyname
1784
1785C<gethostbyname('localhost')> does not work everywhere: you may have
1786to use C<gethostbyname('127.0.0.1')>. (S<Mac OS>, S<Irix 5>)
1787
e41182b5
GS
1788=item gethostent
1789
1790Not implemented. (S<Mac OS>, Win32)
1791
1792=item getnetent
1793
e6f03d26 1794Not implemented. (S<Mac OS>, Win32, S<Plan 9>)
e41182b5
GS
1795
1796=item getprotoent
1797
e6f03d26 1798Not implemented. (S<Mac OS>, Win32, S<Plan 9>)
e41182b5
GS
1799
1800=item getservent
1801
e6f03d26 1802Not implemented. (Win32, S<Plan 9>)
e41182b5 1803
47cd99a4 1804=item sethostent
e41182b5 1805
e6f03d26 1806Not implemented. (S<Mac OS>, Win32, S<Plan 9>, S<RISC OS>)
e41182b5 1807
47cd99a4 1808=item setnetent
e41182b5 1809
e6f03d26 1810Not implemented. (S<Mac OS>, Win32, S<Plan 9>, S<RISC OS>)
e41182b5 1811
47cd99a4 1812=item setprotoent
e41182b5 1813
e6f03d26 1814Not implemented. (S<Mac OS>, Win32, S<Plan 9>, S<RISC OS>)
e41182b5 1815
47cd99a4 1816=item setservent
e41182b5 1817
e6f03d26 1818Not implemented. (S<Plan 9>, Win32, S<RISC OS>)
e41182b5
GS
1819
1820=item endpwent
1821
a3dfe201 1822Not implemented. (S<Mac OS>, MPE/iX, VM/ESA, Win32)
e41182b5
GS
1823
1824=item endgrent
1825
a3dfe201 1826Not implemented. (S<Mac OS>, MPE/iX, S<RISC OS>, VM/ESA, VMS, Win32)
e41182b5
GS
1827
1828=item endhostent
1829
1830Not implemented. (S<Mac OS>, Win32)
1831
1832=item endnetent
1833
e6f03d26 1834Not implemented. (S<Mac OS>, Win32, S<Plan 9>)
e41182b5
GS
1835
1836=item endprotoent
1837
e6f03d26 1838Not implemented. (S<Mac OS>, Win32, S<Plan 9>)
e41182b5
GS
1839
1840=item endservent
1841
e6f03d26 1842Not implemented. (S<Plan 9>, Win32)
e41182b5
GS
1843
1844=item getsockopt SOCKET,LEVEL,OPTNAME
1845
e6f03d26 1846Not implemented. (S<Plan 9>)
e41182b5 1847
e41182b5
GS
1848=item glob
1849
63f87e49
GS
1850This operator is implemented via the File::Glob extension on most
1851platforms. See L<File::Glob> for portability information.
b8099c3d 1852
62aa5637
MS
1853=item gmtime
1854
461d5a49
MS
1855In theory, gmtime() is reliable from -2**63 to 2**63-1. However,
1856because work arounds in the implementation use floating point numbers,
1857it will become inaccurate as the time gets larger. This is a bug and
1858will be fixed in the future.
62aa5637 1859
e41182b5
GS
1860=item ioctl FILEHANDLE,FUNCTION,SCALAR
1861
1862Not implemented. (VMS)
1863
1864Available only for socket handles, and it does what the ioctlsocket() call
1865in the Winsock API does. (Win32)
1866
b8099c3d
CN
1867Available only for socket handles. (S<RISC OS>)
1868
47cd99a4 1869=item kill
e41182b5 1870
862b5365
JH
1871C<kill(0, LIST)> is implemented for the sake of taint checking;
1872use with other signals is unimplemented. (S<Mac OS>)
1873
1874Not implemented, hence not useful for taint checking. (S<RISC OS>)
e41182b5 1875
63f87e49
GS
1876C<kill()> doesn't have the semantics of C<raise()>, i.e. it doesn't send
1877a signal to the identified process like it does on Unix platforms.
1878Instead C<kill($sig, $pid)> terminates the process identified by $pid,
1879and makes it exit immediately with exit status $sig. As in Unix, if
1880$sig is 0 and the specified process exists, it returns true without
1881actually terminating it. (Win32)
e41182b5 1882
d0302514
JD
1883C<kill(-9, $pid)> will terminate the process specified by $pid and
1884recursively all child processes owned by it. This is different from
1885the Unix semantics, where the signal will be delivered to all
1886processes in the same process group as the process specified by
1887$pid. (Win32)
1888
016930a6
JM
1889Is not supported for process identification number of 0 or negative
1890numbers. (VMS)
1891
47cd99a4 1892=item link
e41182b5 1893
016930a6 1894Not implemented. (S<Mac OS>, MPE/iX, S<RISC OS>)
e41182b5 1895
433acd8a
JH
1896Link count not updated because hard links are not quite that hard
1897(They are sort of half-way between hard and soft links). (AmigaOS)
1898
63d6c08b
JD
1899Hard links are implemented on Win32 under NTFS only. They are
1900natively supported on Windows 2000 and later. On Windows NT they
1901are implemented using the Windows POSIX subsystem support and the
1902Perl process will need Administrator or Backup Operator privileges
1903to create hard links.
a3dfe201 1904
016930a6
JM
1905Available on 64 bit OpenVMS 8.2 and later. (VMS)
1906
62aa5637
MS
1907=item localtime
1908
dc164757
MS
1909localtime() has the same range as L<gmtime>, but because time zone
1910rules change its accuracy for historical and future times may degrade
1911but usually by no more than an hour.
62aa5637 1912
e41182b5
GS
1913=item lstat
1914
016930a6 1915Not implemented. (S<RISC OS>)
e41182b5 1916
63f87e49 1917Return values (especially for device and inode) may be bogus. (Win32)
e41182b5 1918
47cd99a4 1919=item msgctl
e41182b5 1920
47cd99a4 1921=item msgget
e41182b5 1922
47cd99a4 1923=item msgsnd
e41182b5 1924
47cd99a4 1925=item msgrcv
e41182b5 1926
e6f03d26 1927Not implemented. (S<Mac OS>, Win32, VMS, S<Plan 9>, S<RISC OS>, VOS)
e41182b5 1928
47cd99a4 1929=item open
e41182b5 1930
b7df3edc 1931The C<|> variants are supported only if ToolServer is installed.
e41182b5
GS
1932(S<Mac OS>)
1933
c47ff5f1 1934open to C<|-> and C<-|> are unsupported. (S<Mac OS>, Win32, S<RISC OS>)
e41182b5 1935
0f897271
GS
1936Opening a process does not automatically flush output handles on some
1937platforms. (SunOS, Solaris, HP-UX)
1938
e41182b5
GS
1939=item readlink
1940
b8099c3d 1941Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5 1942
47cd99a4 1943=item rename
c9b2b9d4
SS
1944
1945Can't move directories between directories on different logical volumes. (Win32)
1946
47cd99a4 1947=item select
e41182b5 1948
689c5c24 1949Only implemented on sockets. (Win32, VMS)
e41182b5 1950
b8099c3d
CN
1951Only reliable on sockets. (S<RISC OS>)
1952
76e05f0b 1953Note that the C<select FILEHANDLE> form is generally portable.
63f87e49 1954
47cd99a4 1955=item semctl
e41182b5 1956
47cd99a4 1957=item semget
e41182b5 1958
47cd99a4 1959=item semop
e41182b5 1960
495c5fdc 1961Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5 1962
a3dfe201
GS
1963=item setgrent
1964
3fd80bd6 1965Not implemented. (S<Mac OS>, MPE/iX, VMS, Win32, S<RISC OS>, VOS)
a3dfe201 1966
47cd99a4 1967=item setpgrp
e41182b5 1968
495c5fdc 1969Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5 1970
47cd99a4 1971=item setpriority
e41182b5 1972
495c5fdc 1973Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5 1974
a3dfe201
GS
1975=item setpwent
1976
3fd80bd6 1977Not implemented. (S<Mac OS>, MPE/iX, Win32, S<RISC OS>, VOS)
a3dfe201 1978
47cd99a4 1979=item setsockopt
e41182b5 1980
e6f03d26 1981Not implemented. (S<Plan 9>)
e41182b5 1982
47cd99a4 1983=item shmctl
e41182b5 1984
47cd99a4 1985=item shmget
e41182b5 1986
47cd99a4 1987=item shmread
e41182b5 1988
47cd99a4 1989=item shmwrite
e41182b5 1990
495c5fdc 1991Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5 1992
47cd99a4 1993=item sockatmark
80cbd5ad
JH
1994
1995A relatively recent addition to socket functions, may not
1996be implemented even in UNIX platforms.
1997
47cd99a4 1998=item socketpair
e41182b5 1999
f38e12df 2000Not implemented. (S<RISC OS>, VOS, VM/ESA)
016930a6
JM
2001
2002Available on 64 bit OpenVMS 8.2 and later. (VMS)
e41182b5 2003
e41182b5
GS
2004=item stat
2005
d62e1b7f
JH
2006Platforms that do not have rdev, blksize, or blocks will return these
2007as '', so numeric comparison or manipulation of these fields may cause
2008'not numeric' warnings.
2009
e41182b5 2010mtime and atime are the same thing, and ctime is creation time instead of
3f1f789b
JH
2011inode change time. (S<Mac OS>).
2012
2013ctime not supported on UFS (S<Mac OS X>).
e41182b5 2014
95a3fe12
MS
2015ctime is creation time instead of inode change time (Win32).
2016
e41182b5
GS
2017device and inode are not meaningful. (Win32)
2018
2019device and inode are not necessarily reliable. (VMS)
2020
b8099c3d
CN
2021mtime, atime and ctime all return the last modification time. Device and
2022inode are not necessarily reliable. (S<RISC OS>)
2023
d62e1b7f
JH
2024dev, rdev, blksize, and blocks are not available. inode is not
2025meaningful and will differ between stat calls on the same file. (os2)
2026
73e9292c
JH
2027some versions of cygwin when doing a stat("foo") and if not finding it
2028may then attempt to stat("foo.exe") (Cygwin)
2029
1fafdf34
JD
2030On Win32 stat() needs to open the file to determine the link count
2031and update attributes that may have been changed through hard links.
2032Setting ${^WIN32_SLOPPY_STAT} to a true value speeds up stat() by
2033not performing this operation. (Win32)
2034
47cd99a4 2035=item symlink
e41182b5 2036
c73b03b7
JM
2037Not implemented. (Win32, S<RISC OS>)
2038
2039Implemented on 64 bit VMS 8.3. VMS requires the symbolic link to be in Unix
2040syntax if it is intended to resolve to a valid path.
e41182b5 2041
47cd99a4 2042=item syscall
e41182b5 2043
7c5ffed3 2044Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
e41182b5 2045
47cd99a4 2046=item sysopen
f34d0673 2047
dd9f0070 2048The traditional "0", "1", and "2" MODEs are implemented with different
322422de
GS
2049numeric values on some systems. The flags exported by C<Fcntl>
2050(O_RDONLY, O_WRONLY, O_RDWR) should work everywhere though. (S<Mac
7c5ffed3 2051OS>, OS/390, VM/ESA)
f34d0673 2052
47cd99a4 2053=item system
e41182b5
GS
2054
2055Only implemented if ToolServer is installed. (S<Mac OS>)
2056
2057As an optimization, may not call the command shell specified in
b7df3edc 2058C<$ENV{PERL5SHELL}>. C<system(1, @args)> spawns an external
e41182b5
GS
2059process and immediately returns its process designator, without
2060waiting for it to terminate. Return value may be used subsequently
63f87e49
GS
2061in C<wait> or C<waitpid>. Failure to spawn() a subprocess is indicated
2062by setting $? to "255 << 8". C<$?> is set in a way compatible with
2063Unix (i.e. the exitstatus of the subprocess is obtained by "$? >> 8",
2064as described in the documentation). (Win32)
e41182b5 2065
b8099c3d
CN
2066There is no shell to process metacharacters, and the native standard is
2067to pass a command line terminated by "\n" "\r" or "\0" to the spawned
c47ff5f1 2068program. Redirection such as C<< > foo >> is performed (if at all) by
b8099c3d
CN
2069the run time library of the spawned program. C<system> I<list> will call
2070the Unix emulation library's C<exec> emulation, which attempts to provide
2071emulation of the stdin, stdout, stderr in force in the parent, providing
2072the child program uses a compatible version of the emulation library.
2073I<scalar> will call the native command line direct and no such emulation
2074of a child Unix program will exists. Mileage B<will> vary. (S<RISC OS>)
2075
0f897271
GS
2076Does not automatically flush output handles on some platforms.
2077(SunOS, Solaris, HP-UX)
2078
9bc98430
CB
2079The return value is POSIX-like (shifted up by 8 bits), which only allows
2080room for a made-up value derived from the severity bits of the native
208132-bit condition code (unless overridden by C<use vmsish 'status'>).
016930a6
JM
2082If the native condition code is one that has a POSIX value encoded, the
2083POSIX value will be decoded to extract the expected exit value.
9bc98430
CB
2084For more details see L<perlvms/$?>. (VMS)
2085
e41182b5
GS
2086=item times
2087
2088Only the first entry returned is nonzero. (S<Mac OS>)
2089
63f87e49
GS
2090"cumulative" times will be bogus. On anything other than Windows NT
2091or Windows 2000, "system" time will be bogus, and "user" time is
2092actually the time returned by the clock() function in the C runtime
2093library. (Win32)
e41182b5 2094
b8099c3d
CN
2095Not useful. (S<RISC OS>)
2096
47cd99a4 2097=item truncate
e41182b5 2098
6d738113 2099Not implemented. (Older versions of VMS)
e41182b5 2100
3fd80bd6 2101Truncation to same-or-shorter lengths only. (VOS)
495c5fdc 2102
4cfdb94f 2103If a FILEHANDLE is supplied, it must be writable and opened in append
e71a7dc8 2104mode (i.e., use C<<< open(FH, '>>filename') >>>
4cfdb94f
GS
2105or C<sysopen(FH,...,O_APPEND|O_RDWR)>. If a filename is supplied, it
2106should not be held open elsewhere. (Win32)
2107
e41182b5
GS
2108=item umask
2109
2110Returns undef where unavailable, as of version 5.005.
2111
b7df3edc
GS
2112C<umask> works but the correct permissions are set only when the file
2113is finally closed. (AmigaOS)
433acd8a 2114
47cd99a4 2115=item utime
e41182b5 2116
15c65113 2117Only the modification time is updated. (S<BeOS>, S<Mac OS>, VMS, S<RISC OS>)
e41182b5 2118
322422de
GS
2119May not behave as expected. Behavior depends on the C runtime
2120library's implementation of utime(), and the filesystem being
2121used. The FAT filesystem typically does not support an "access
2122time" field, and it may limit timestamps to a granularity of
2123two seconds. (Win32)
e41182b5
GS
2124
2125=item wait
2126
47cd99a4 2127=item waitpid
e41182b5 2128
3fd80bd6 2129Not implemented. (S<Mac OS>)
e41182b5
GS
2130
2131Can only be applied to process handles returned for processes spawned
a6f858fb 2132using C<system(1, ...)> or pseudo processes created with C<fork()>. (Win32)
e41182b5 2133
b8099c3d
CN
2134Not useful. (S<RISC OS>)
2135
e41182b5
GS
2136=back
2137
2138
ba58ab26
JH
2139=head1 Supported Platforms
2140
522b859a 2141As of July 2002 (the Perl release 5.8.0), the following platforms are
cec2c193 2142able to build Perl from the standard source code distribution
e59066d8 2143available at http://www.cpan.org/src/
cec2c193
JH
2144
2145 AIX
2146 BeOS
6f683aa2 2147 BSD/OS (BSDi)
cec2c193
JH
2148 Cygwin
2149 DG/UX
811b48f2 2150 DOS DJGPP 1)
cec2c193
JH
2151 DYNIX/ptx
2152 EPOC R5
2153 FreeBSD
6f683aa2 2154 HI-UXMPP (Hitachi) (5.8.0 worked but we didn't know it)
cec2c193
JH
2155 HP-UX
2156 IRIX
2157 Linux
8939ba94 2158 Mac OS Classic
6f683aa2 2159 Mac OS X (Darwin)
cec2c193
JH
2160 MPE/iX
2161 NetBSD
2162 NetWare
2163 NonStop-UX
6f683aa2 2164 ReliantUNIX (formerly SINIX)
cec2c193 2165 OpenBSD
6f683aa2 2166 OpenVMS (formerly VMS)
3ebac25b 2167 Open UNIX (Unixware) (since Perl 5.8.1/5.9.0)
cec2c193 2168 OS/2
522b859a 2169 OS/400 (using the PASE) (since Perl 5.8.1/5.9.0)
70de81db 2170 PowerUX
6f683aa2 2171 POSIX-BC (formerly BS2000)
cec2c193
JH
2172 QNX
2173 Solaris
70de81db 2174 SunOS 4
6f683aa2
JH
2175 SUPER-UX (NEC)
2176 Tru64 UNIX (formerly DEC OSF/1, Digital UNIX)
cec2c193
JH
2177 UNICOS
2178 UNICOS/mk
2179 UTS
2180 VOS
811b48f2 2181 Win95/98/ME/2K/XP 2)
c40b5d1d 2182 WinCE
6f683aa2 2183 z/OS (formerly OS/390)
cec2c193 2184 VM/ESA
ba58ab26 2185
811b48f2
JH
2186 1) in DOS mode either the DOS or OS/2 ports can be used
2187 2) compilers: Borland, MinGW (GCC), VC6
cec2c193 2188
c40b5d1d 2189The following platforms worked with the previous releases (5.6 and
cec2c193
JH
21905.7), but we did not manage either to fix or to test these in time
2191for the 5.8.0 release. There is a very good chance that many of these
70de81db 2192will work fine with the 5.8.0.
cec2c193 2193
8da2b1be 2194 BSD/OS
cec2c193
JH
2195 DomainOS
2196 Hurd
2197 LynxOS
2198 MachTen
2199 PowerMAX
2200 SCO SV
cec2c193
JH
2201 SVR4
2202 Unixware
2203 Windows 3.1
ba58ab26 2204
70de81db
JH
2205Known to be broken for 5.8.0 (but 5.6.1 and 5.7.2 can be used):
2206
2207 AmigaOS
2208
ba58ab26 2209The following platforms have been known to build Perl from source in
fd46a41b
JH
2210the past (5.005_03 and earlier), but we haven't been able to verify
2211their status for the current release, either because the
2212hardware/software platforms are rare or because we don't have an
2213active champion on these platforms--or both. They used to work,
2214though, so go ahead and try compiling them, and let perlbug@perl.org
2215of any trouble.
ba58ab26 2216
cec2c193
JH
2217 3b1
2218 A/UX
cec2c193
JH
2219 ConvexOS
2220 CX/UX
2221 DC/OSx
2222 DDE SMES
2223 DOS EMX
2224 Dynix
2225 EP/IX
2226 ESIX
2227 FPS
2228 GENIX
2229 Greenhills
2230 ISC
2231 MachTen 68k
cec2c193
JH
2232 MPC
2233 NEWS-OS
2234 NextSTEP
2235 OpenSTEP
2236 Opus
2237 Plan 9
cec2c193 2238 RISC/os
8da2b1be 2239 SCO ODT/OSR
cec2c193
JH
2240 Stellar
2241 SVR2
2242 TI1500
2243 TitanOS
2244 Ultrix
2245 Unisys Dynix
ba58ab26
JH
2246
2247The following platforms have their own source code distributions and
1577cd80 2248binaries available via http://www.cpan.org/ports/
ba58ab26 2249
cec2c193 2250 Perl release
ba58ab26 2251
522b859a 2252 OS/400 (ILE) 5.005_02
cec2c193 2253 Tandem Guardian 5.004
ba58ab26
JH
2254
2255The following platforms have only binaries available via
a93751fa 2256http://www.cpan.org/ports/index.html :
ba58ab26 2257
cec2c193 2258 Perl release
ba58ab26 2259
cec2c193
JH
2260 Acorn RISCOS 5.005_02
2261 AOS 5.002
2262 LynxOS 5.004_02
ba58ab26
JH
2263
2264Although we do suggest that you always build your own Perl from
2265the source code, both for maximal configurability and for security,
2266in case you are in a hurry you can check
a93751fa 2267http://www.cpan.org/ports/index.html for binary distributions.
ba58ab26 2268
c997b287
GS
2269=head1 SEE ALSO
2270
cec2c193 2271L<perlaix>, L<perlamiga>, L<perlapollo>, L<perlbeos>, L<perlbs2000>,
18a271bd 2272L<perlce>, L<perlcygwin>, L<perldgux>, L<perldos>, L<perlepoc>,
469e7be4 2273L<perlebcdic>, L<perlfreebsd>, L<perlhurd>, L<perlhpux>, L<perlirix>,
e94c1c05 2274L<perlmacos>, L<perlmacosx>, L<perlmpeix>,
522b859a
JH
2275L<perlnetware>, L<perlos2>, L<perlos390>, L<perlos400>,
2276L<perlplan9>, L<perlqnx>, L<perlsolaris>, L<perltru64>,
2277L<perlunicode>, L<perlvmesa>, L<perlvms>, L<perlvos>,
2278L<perlwin32>, and L<Win32>.
c997b287 2279
e41182b5
GS
2280=head1 AUTHORS / CONTRIBUTORS
2281
06e9666b 2282Abigail <abigail@foad.org>,
c47ff5f1
GS
2283Charles Bailey <bailey@newman.upenn.edu>,
2284Graham Barr <gbarr@pobox.com>,
2285Tom Christiansen <tchrist@perl.com>,
06e9666b 2286Nicholas Clark <nick@ccl4.org>,
c47ff5f1 2287Thomas Dorner <Thomas.Dorner@start.de>,
06e9666b
A
2288Andy Dougherty <doughera@lafayette.edu>,
2289Dominic Dunlop <domo@computer.org>,
2290Neale Ferguson <neale@vma.tabnsw.com.au>,
c47ff5f1 2291David J. Fiander <davidf@mks.com>,
3fd80bd6 2292Paul Green <Paul.Green@stratus.com>,
06e9666b 2293M.J.T. Guy <mjtg@cam.ac.uk>,
61f30a5e 2294Jarkko Hietaniemi <jhi@iki.fi>,
c47ff5f1 2295Luther Huffman <lutherh@stratcom.com>,
06e9666b
A
2296Nick Ing-Simmons <nick@ing-simmons.net>,
2297Andreas J. KE<ouml>nig <a.koenig@mind.de>,
c47ff5f1
GS
2298Markus Laker <mlaker@contax.co.uk>,
2299Andrew M. Langmead <aml@world.std.com>,
2300Larry Moore <ljmoore@freespace.net>,
2301Paul Moore <Paul.Moore@uk.origin-it.com>,
2302Chris Nandor <pudge@pobox.com>,
1afc07ec 2303Matthias Neeracher <neeracher@mac.com>,
e71a7dc8 2304Philip Newton <pne@cpan.org>,
c47ff5f1
GS
2305Gary Ng <71564.1743@CompuServe.COM>,
2306Tom Phoenix <rootbeer@teleport.com>,
2307AndrE<eacute> Pirard <A.Pirard@ulg.ac.be>,
2308Peter Prymmer <pvhp@forte.com>,
2309Hugo van der Sanden <hv@crypt0.demon.co.uk>,
2310Gurusamy Sarathy <gsar@activestate.com>,
2311Paul J. Schinder <schinder@pobox.com>,
2312Michael G Schwern <schwern@pobox.com>,
06e9666b 2313Dan Sugalski <dan@sidhe.org>,
c47ff5f1 2314Nathan Torkington <gnat@frii.com>.
016930a6 2315John Malmberg <wb8tyw@qsl.net>