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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,
204ad8d5 62VMS, etc.), consider writing platform-specific code.
e41182b5 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
1bcbdd38 215As of perl 5.10.0, 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
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239binary, or else consider using modules like Data::Dumper and Storable
240(included as of perl 5.8). Keeping all data as text significantly
241simplifies 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:).
322422de 262
204ad8d5 263S<Mac OS> 9 and earlier used C<:> as a path separator instead of C</>.
322422de 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
e1020413 274"creation timestamp" (which it is not in Unix).
95a3fe12 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
e1020413 284Don't assume Unix filesystem access semantics: that read, write,
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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
e1020413 287a directory) are the Unix ones. The various Unix/POSIX compatibility
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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
ceaffd1d 298 my $file = catfile(curdir(), 'temp', 'file.txt');
e41182b5 299 # on Unix and Win32, './temp/file.txt'
204ad8d5 300 # on Mac OS Classic, ':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
ceaffd1d 359 open my $fh, '<', $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
c87488a3 454Don't count on specific values of C<$!>, neither numeric nor
ac036724 455especially the strings values. Users may switch their locales causing
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456error messages to be translated into their languages. If you can
457trust a POSIXish environment, you can portably use the symbols defined
458by the Errno module, like ENOENT. And don't trust on the values of C<$!>
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,
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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.
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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
a61fc69c
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483 use Config;
484 my $thisperl = $^X;
485 if ($^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
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490 use Config;
491 my $thisperl = $Config{perlpath};
492 if ($^O ne 'VMS')
493 {$thisperl .= $Config{_exe} unless $thisperl =~ m/$Config{_exe}$/i;}
a10d74f3 494
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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
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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
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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
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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.
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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
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519Don't assume that any particular port (service) will respond.
520
ac036724 521Don't assume that Sys::Hostname (or any other API or command) returns
522either a fully qualified hostname or a non-qualified hostname: it all
523depends on how the system had been configured. Also remember that for
524things such as DHCP and NAT, the hostname you get back might not be
525very useful.
dbc6a9ce 526
ac036724 527All the above "don't":s may look daunting, and they are, but the key
932f293e
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528is to degrade gracefully if one cannot reach the particular network
529service one wants. Croaking or hanging do not look very professional.
530
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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
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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
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575use a module (that may internally implement it with platform-specific
576code, but expose a common interface).
e41182b5 577
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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
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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
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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.
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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
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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
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623because that is OS- and implementation-specific. It is better to
624store a date in an unambiguous representation. The ISO 8601 standard
766af94f 625defines YYYY-MM-DD as the date format, or YYYY-MM-DDTHH:MM:SS
c87488a3 626(that's a literal "T" separating the date from the time).
91d20606 627Please do use the ISO 8601 instead of making us guess what
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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
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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 637 require Time::Local;
ceaffd1d 638 my $offset = Time::Local::timegm(0, 0, 0, 1, 0, 70);
b7df3edc 639
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JV
640The value for C<$offset> in Unix will be C<0>, but in Mac OS Classic
641will be some large number. C<$offset> can then be added to a Unix time
642value to get what should be the proper value on any system.
322422de
GS
643
644=head2 Character sets and character encoding
645
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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".
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GS
660
661=head2 Internationalisation
662
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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
HS
670If you really want to be international, you should consider Unicode.
671See L<perluniintro> and L<perlunicode> for more information.
672
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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
1bcbdd38
BF
682of embedding the bytes as-is. If you want to write your code in UTF-8,
683you can use the C<utf8>.
11264fdb 684
e41182b5
GS
685=head2 System Resources
686
0a47030a
GS
687If your code is destined for systems with severely constrained (or
688missing!) virtual memory systems then you want to be I<especially> mindful
689of avoiding wasteful constructs such as:
e41182b5 690
ceaffd1d 691 my @lines = <$very_large_file>; # bad
e41182b5 692
ceaffd1d 693 while (<$fh>) {$file .= $_} # sometimes bad
694 my $file = join('', <$fh>); # better
e41182b5 695
b7df3edc
GS
696The last two constructs may appear unintuitive to most people. The
697first repeatedly grows a string, whereas the second allocates a
698large chunk of memory in one go. On some systems, the second is
699more efficient that the first.
0a47030a 700
e41182b5
GS
701=head2 Security
702
b7df3edc 703Most multi-user platforms provide basic levels of security, usually
ac036724 704implemented at the filesystem level. Some, however, unfortunately do
705not. Thus the notion of user id, or "home" directory,
b7df3edc
GS
706or even the state of being logged-in, may be unrecognizable on many
707platforms. If you write programs that are security-conscious, it
708is usually best to know what type of system you will be running
709under so that you can write code explicitly for that platform (or
710class of platforms).
0a47030a 711
e1020413 712Don't assume the Unix filesystem access semantics: the operating
a1667ba3
JH
713system or the filesystem may be using some ACL systems, which are
714richer languages than the usual rwx. Even if the rwx exist,
715their semantics might be different.
716
717(From security viewpoint testing for permissions before attempting to
718do something is silly anyway: if one tries this, there is potential
ac036724 719for race conditions. Someone or something might change the
a1667ba3
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720permissions between the permissions check and the actual operation.
721Just try the operation.)
722
e1020413 723Don't assume the Unix user and group semantics: especially, don't
2edcc0d9 724expect the C<< $< >> and C<< $> >> (or the C<$(> and C<$)>) to work
a1667ba3
JH
725for switching identities (or memberships).
726
727Don't assume set-uid and set-gid semantics. (And even if you do,
728think twice: set-uid and set-gid are a known can of security worms.)
729
e41182b5
GS
730=head2 Style
731
732For those times when it is necessary to have platform-specific code,
733consider keeping the platform-specific code in one place, making porting
6ab3f9cb 734to other platforms easier. Use the Config module and the special
0a47030a
GS
735variable C<$^O> to differentiate platforms, as described in
736L<"PLATFORMS">.
e41182b5 737
b7df3edc
GS
738Be careful in the tests you supply with your module or programs.
739Module code may be fully portable, but its tests might not be. This
740often happens when tests spawn off other processes or call external
741programs to aid in the testing, or when (as noted above) the tests
c87488a3
HS
742assume certain things about the filesystem and paths. Be careful not
743to depend on a specific output style for errors, such as when checking
744C<$!> after a failed system call. Using C<$!> for anything else than
745displaying it as output is doubtful (though see the Errno module for
746testing reasonably portably for error value). Some platforms expect
747a certain output format, and Perl on those platforms may have been
748adjusted accordingly. Most specifically, don't anchor a regex when
749testing an error value.
e41182b5 750
0a47030a 751=head1 CPAN Testers
e41182b5 752
0a47030a
GS
753Modules uploaded to CPAN are tested by a variety of volunteers on
754different platforms. These CPAN testers are notified by mail of each
e41182b5 755new upload, and reply to the list with PASS, FAIL, NA (not applicable to
0a47030a 756this platform), or UNKNOWN (unknown), along with any relevant notations.
e41182b5
GS
757
758The purpose of the testing is twofold: one, to help developers fix any
0a47030a 759problems in their code that crop up because of lack of testing on other
b7df3edc 760platforms; two, to provide users with information about whether
0a47030a 761a given module works on a given platform.
e41182b5 762
7ee27b7c
AT
763Also see:
764
e41182b5
GS
765=over 4
766
7ee27b7c
AT
767=item *
768
636280bd 769Mailing list: cpan-testers-discuss@perl.org
7ee27b7c
AT
770
771=item *
e41182b5 772
500f1b69 773Testing results: L<http://www.cpantesters.org/>
e41182b5
GS
774
775=back
776
e41182b5
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777=head1 PLATFORMS
778
1bcbdd38
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779Perl is built with a C<$^O> variable that indicates the operating
780system it was built on. This was implemented
b7df3edc
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781to help speed up code that would otherwise have to C<use Config>
782and use the value of C<$Config{osname}>. Of course, to get more
e41182b5
GS
783detailed information about the system, looking into C<%Config> is
784certainly recommended.
785
b7df3edc
GS
786C<%Config> cannot always be trusted, however, because it was built
787at compile time. If perl was built in one place, then transferred
788elsewhere, some values may be wrong. The values may even have been
789edited after the fact.
6ab3f9cb 790
e41182b5
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791=head2 Unix
792
793Perl works on a bewildering variety of Unix and Unix-like platforms (see
794e.g. most of the files in the F<hints/> directory in the source code kit).
795On most of these systems, the value of C<$^O> (hence C<$Config{'osname'}>,
d1e3b762
GS
796too) is determined either by lowercasing and stripping punctuation from the
797first field of the string returned by typing C<uname -a> (or a similar command)
798at the shell prompt or by testing the file system for the presence of
799uniquely named files such as a kernel or header file. Here, for example,
800are a few of the more popular Unix flavors:
e41182b5 801
b7df3edc 802 uname $^O $Config{'archname'}
6ab3f9cb 803 --------------------------------------------
b7df3edc 804 AIX aix aix
6ab3f9cb 805 BSD/OS bsdos i386-bsdos
e1516da7 806 Darwin darwin darwin
6ab3f9cb 807 DYNIX/ptx dynixptx i386-dynixptx
b7df3edc 808 FreeBSD freebsd freebsd-i386
df00ff3b 809 Haiku haiku BePC-haiku
d1e3b762 810 Linux linux arm-linux
b7df3edc 811 Linux linux i386-linux
6ab3f9cb
GS
812 Linux linux i586-linux
813 Linux linux ppc-linux
b7df3edc
GS
814 HP-UX hpux PA-RISC1.1
815 IRIX irix irix
b787fad4 816 Mac OS X darwin darwin
d1e3b762
GS
817 NeXT 3 next next-fat
818 NeXT 4 next OPENSTEP-Mach
6ab3f9cb 819 openbsd openbsd i386-openbsd
b7df3edc 820 OSF1 dec_osf alpha-dec_osf
6ab3f9cb
GS
821 reliantunix-n svr4 RM400-svr4
822 SCO_SV sco_sv i386-sco_sv
823 SINIX-N svr4 RM400-svr4
824 sn4609 unicos CRAY_C90-unicos
825 sn6521 unicosmk t3e-unicosmk
826 sn9617 unicos CRAY_J90-unicos
b7df3edc
GS
827 SunOS solaris sun4-solaris
828 SunOS solaris i86pc-solaris
829 SunOS4 sunos sun4-sunos
e41182b5 830
b7df3edc
GS
831Because the value of C<$Config{archname}> may depend on the
832hardware architecture, it can vary more than the value of C<$^O>.
6ab3f9cb 833
e41182b5
GS
834=head2 DOS and Derivatives
835
b7df3edc 836Perl has long been ported to Intel-style microcomputers running under
e41182b5
GS
837systems like PC-DOS, MS-DOS, OS/2, and most Windows platforms you can
838bring yourself to mention (except for Windows CE, if you count that).
b7df3edc 839Users familiar with I<COMMAND.COM> or I<CMD.EXE> style shells should
e41182b5
GS
840be aware that each of these file specifications may have subtle
841differences:
842
ceaffd1d 843 my $filespec0 = "c:/foo/bar/file.txt";
844 my $filespec1 = "c:\\foo\\bar\\file.txt";
845 my $filespec2 = 'c:\foo\bar\file.txt';
846 my $filespec3 = 'c:\\foo\\bar\\file.txt';
e41182b5 847
b7df3edc
GS
848System calls accept either C</> or C<\> as the path separator.
849However, many command-line utilities of DOS vintage treat C</> as
850the option prefix, so may get confused by filenames containing C</>.
851Aside from calling any external programs, C</> will work just fine,
852and probably better, as it is more consistent with popular usage,
853and avoids the problem of remembering what to backwhack and what
854not to.
e41182b5 855
b7df3edc
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856The DOS FAT filesystem can accommodate only "8.3" style filenames. Under
857the "case-insensitive, but case-preserving" HPFS (OS/2) and NTFS (NT)
0a47030a 858filesystems you may have to be careful about case returned with functions
e41182b5
GS
859like C<readdir> or used with functions like C<open> or C<opendir>.
860
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GS
861DOS also treats several filenames as special, such as AUX, PRN,
862NUL, CON, COM1, LPT1, LPT2, etc. Unfortunately, sometimes these
863filenames won't even work if you include an explicit directory
864prefix. It is best to avoid such filenames, if you want your code
865to be portable to DOS and its derivatives. It's hard to know what
866these all are, unfortunately.
e41182b5
GS
867
868Users of these operating systems may also wish to make use of
b7df3edc 869scripts such as I<pl2bat.bat> or I<pl2cmd> to
e41182b5
GS
870put wrappers around your scripts.
871
872Newline (C<\n>) is translated as C<\015\012> by STDIO when reading from
6ab3f9cb
GS
873and writing to files (see L<"Newlines">). C<binmode(FILEHANDLE)>
874will keep C<\n> translated as C<\012> for that filehandle. Since it is a
875no-op on other systems, C<binmode> should be used for cross-platform code
b7df3edc
GS
876that deals with binary data. That's assuming you realize in advance
877that your data is in binary. General-purpose programs should
878often assume nothing about their data.
e41182b5 879
b7df3edc 880The C<$^O> variable and the C<$Config{archname}> values for various
e41182b5
GS
881DOSish perls are as follows:
882
67ac489e
MS
883 OS $^O $Config{archname} ID Version
884 --------------------------------------------------------
885 MS-DOS dos ?
886 PC-DOS dos ?
887 OS/2 os2 ?
888 Windows 3.1 ? ? 0 3 01
889 Windows 95 MSWin32 MSWin32-x86 1 4 00
890 Windows 98 MSWin32 MSWin32-x86 1 4 10
891 Windows ME MSWin32 MSWin32-x86 1 ?
892 Windows NT MSWin32 MSWin32-x86 2 4 xx
893 Windows NT MSWin32 MSWin32-ALPHA 2 4 xx
894 Windows NT MSWin32 MSWin32-ppc 2 4 xx
7ee27b7c
AT
895 Windows 2000 MSWin32 MSWin32-x86 2 5 00
896 Windows XP MSWin32 MSWin32-x86 2 5 01
897 Windows 2003 MSWin32 MSWin32-x86 2 5 02
bc643a33
CJ
898 Windows Vista MSWin32 MSWin32-x86 2 6 00
899 Windows 7 MSWin32 MSWin32-x86 2 6 01
900 Windows 7 MSWin32 MSWin32-x64 2 6 01
ae525322
CBW
901 Windows 2008 MSWin32 MSWin32-x86 2 6 01
902 Windows 2008 MSWin32 MSWin32-x64 2 6 01
67ac489e 903 Windows CE MSWin32 ? 3
7ee27b7c 904 Cygwin cygwin cygwin
e41182b5 905
34aaaa84
PP
906The various MSWin32 Perl's can distinguish the OS they are running on
907via the value of the fifth element of the list returned from
908Win32::GetOSVersion(). For example:
909
910 if ($^O eq 'MSWin32') {
911 my @os_version_info = Win32::GetOSVersion();
912 print +('3.1','95','NT')[$os_version_info[4]],"\n";
913 }
914
7939d86b
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915There are also Win32::IsWinNT() and Win32::IsWin95(), try C<perldoc Win32>,
916and as of libwin32 0.19 (not part of the core Perl distribution)
917Win32::GetOSName(). The very portable POSIX::uname() will work too:
1d65be3a
JH
918
919 c:\> perl -MPOSIX -we "print join '|', uname"
920 Windows NT|moonru|5.0|Build 2195 (Service Pack 2)|x86
d99f392e 921
e41182b5
GS
922Also see:
923
924=over 4
925
c997b287 926=item *
e41182b5 927
500f1b69 928The djgpp environment for DOS, L<http://www.delorie.com/djgpp/>
c997b287 929and L<perldos>.
e41182b5 930
c997b287 931=item *
e41182b5 932
c997b287 933The EMX environment for DOS, OS/2, etc. emx@iaehv.nl,
500f1b69 934L<ftp://hobbes.nmsu.edu/pub/os2/dev/emx/> Also L<perlos2>.
e41182b5 935
c997b287 936=item *
d1e3b762 937
c997b287
GS
938Build instructions for Win32 in L<perlwin32>, or under the Cygnus environment
939in L<perlcygwin>.
940
941=item *
942
943The C<Win32::*> modules in L<Win32>.
944
945=item *
946
500f1b69 947The ActiveState Pages, L<http://www.activestate.com/>
c997b287
GS
948
949=item *
950
951The Cygwin environment for Win32; F<README.cygwin> (installed
500f1b69 952as L<perlcygwin>), L<http://www.cygwin.com/>
c997b287
GS
953
954=item *
955
956The U/WIN environment for Win32,
500f1b69 957L<http://www.research.att.com/sw/tools/uwin/>
c997b287 958
cea6626f 959=item *
d1e3b762 960
cea6626f 961Build instructions for OS/2, L<perlos2>
d1e3b762 962
e41182b5
GS
963=back
964
e41182b5
GS
965=head2 VMS
966
c997b287 967Perl on VMS is discussed in L<perlvms> in the perl distribution.
016930a6
JM
968
969The official name of VMS as of this writing is OpenVMS.
970
b7df3edc 971Perl on VMS can accept either VMS- or Unix-style file
e41182b5
GS
972specifications as in either of the following:
973
974 $ perl -ne "print if /perl_setup/i" SYS$LOGIN:LOGIN.COM
975 $ perl -ne "print if /perl_setup/i" /sys$login/login.com
976
977but not a mixture of both as in:
978
979 $ perl -ne "print if /perl_setup/i" sys$login:/login.com
980 Can't open sys$login:/login.com: file specification syntax error
981
982Interacting with Perl from the Digital Command Language (DCL) shell
983often requires a different set of quotation marks than Unix shells do.
984For example:
985
986 $ perl -e "print ""Hello, world.\n"""
987 Hello, world.
988
b7df3edc 989There are several ways to wrap your perl scripts in DCL F<.COM> files, if
e41182b5
GS
990you are so inclined. For example:
991
992 $ write sys$output "Hello from DCL!"
993 $ if p1 .eqs. ""
994 $ then perl -x 'f$environment("PROCEDURE")
995 $ else perl -x - 'p1 'p2 'p3 'p4 'p5 'p6 'p7 'p8
996 $ deck/dollars="__END__"
997 #!/usr/bin/perl
998
999 print "Hello from Perl!\n";
1000
1001 __END__
1002 $ endif
1003
1004Do take care with C<$ ASSIGN/nolog/user SYS$COMMAND: SYS$INPUT> if your
c47ff5f1 1005perl-in-DCL script expects to do things like C<< $read = <STDIN>; >>.
e41182b5 1006
016930a6
JM
1007The VMS operating system has two filesystems, known as ODS-2 and ODS-5.
1008
1009For ODS-2, filenames are in the format "name.extension;version". The
1010maximum length for filenames is 39 characters, and the maximum length for
e41182b5
GS
1011extensions is also 39 characters. Version is a number from 1 to
101232767. Valid characters are C</[A-Z0-9$_-]/>.
1013
016930a6
JM
1014The ODS-2 filesystem is case-insensitive and does not preserve case.
1015Perl simulates this by converting all filenames to lowercase internally.
1016
1017For ODS-5, filenames may have almost any character in them and can include
1018Unicode characters. Characters that could be misinterpreted by the DCL
1019shell or file parsing utilities need to be prefixed with the C<^>
1020character, or replaced with hexadecimal characters prefixed with the
1021C<^> character. Such prefixing is only needed with the pathnames are
e1020413 1022in VMS format in applications. Programs that can accept the Unix format
016930a6
JM
1023of pathnames do not need the escape characters. The maximum length for
1024filenames is 255 characters. The ODS-5 file system can handle both
1025a case preserved and a case sensitive mode.
1026
1027ODS-5 is only available on the OpenVMS for 64 bit platforms.
1028
1029Support for the extended file specifications is being done as optional
1030settings to preserve backward compatibility with Perl scripts that
1031assume the previous VMS limitations.
1032
e1020413
TC
1033In general routines on VMS that get a Unix format file specification
1034should return it in a Unix format, and when they get a VMS format
016930a6
JM
1035specification they should return a VMS format unless they are documented
1036to do a conversion.
1037
1038For routines that generate return a file specification, VMS allows setting
1039if the C library which Perl is built on if it will be returned in VMS
e1020413 1040format or in Unix format.
016930a6
JM
1041
1042With the ODS-2 file system, there is not much difference in syntax of
e1020413 1043filenames without paths for VMS or Unix. With the extended character
016930a6
JM
1044set available with ODS-5 there can be a significant difference.
1045
1046Because of this, existing Perl scripts written for VMS were sometimes
e1020413 1047treating VMS and Unix filenames interchangeably. Without the extended
016930a6
JM
1048character set enabled, this behavior will mostly be maintained for
1049backwards compatibility.
1050
1051When extended characters are enabled with ODS-5, the handling of
e1020413 1052Unix formatted file specifications is to that of a Unix system.
016930a6
JM
1053
1054VMS file specifications without extensions have a trailing dot. An
e1020413 1055equivalent Unix file specification should not show the trailing dot.
016930a6
JM
1056
1057The result of all of this, is that for VMS, for portable scripts, you
1058can not depend on Perl to present the filenames in lowercase, to be
1059case sensitive, and that the filenames could be returned in either
e1020413 1060Unix or VMS format.
016930a6
JM
1061
1062And if a routine returns a file specification, unless it is intended to
1063convert it, it should return it in the same format as it found it.
1064
1065C<readdir> by default has traditionally returned lowercased filenames.
1066When the ODS-5 support is enabled, it will return the exact case of the
1067filename on the disk.
1068
1069Files without extensions have a trailing period on them, so doing a
1070C<readdir> in the default mode with a file named F<A.;5> will
1071return F<a.> when VMS is (though that file could be opened with
0a47030a 1072C<open(FH, 'A')>).
e41182b5 1073
016930a6 1074With support for extended file specifications and if C<opendir> was
e1020413 1075given a Unix format directory, a file named F<A.;5> will return F<a>
016930a6
JM
1076and optionally in the exact case on the disk. When C<opendir> is given
1077a VMS format directory, then C<readdir> should return F<a.>, and
1078again with the optionally the exact case.
1079
f34d0673 1080RMS had an eight level limit on directory depths from any rooted logical
1089a9e3
CB
1081(allowing 16 levels overall) prior to VMS 7.2, and even with versions of
1082VMS on VAX up through 7.3. Hence C<PERL_ROOT:[LIB.2.3.4.5.6.7.8]> is a
1083valid directory specification but C<PERL_ROOT:[LIB.2.3.4.5.6.7.8.9]> is
1084not. F<Makefile.PL> authors might have to take this into account, but at
1085least they can refer to the former as C</PERL_ROOT/lib/2/3/4/5/6/7/8/>.
1086
1087Pumpkings and module integrators can easily see whether files with too many
1088directory levels have snuck into the core by running the following in the
1089top-level source directory:
1090
a61fc69c 1091 $ perl -ne "$_=~s/\s+.*//; print if scalar(split /\//) > 8;" < MANIFEST
1089a9e3 1092
e41182b5 1093
6ab3f9cb 1094The VMS::Filespec module, which gets installed as part of the build
0a47030a
GS
1095process on VMS, is a pure Perl module that can easily be installed on
1096non-VMS platforms and can be helpful for conversions to and from RMS
016930a6
JM
1097native formats. It is also now the only way that you should check to
1098see if VMS is in a case sensitive mode.
e41182b5 1099
5e12dbfa
PP
1100What C<\n> represents depends on the type of file opened. It usually
1101represents C<\012> but it could also be C<\015>, C<\012>, C<\015\012>,
fa11829f 1102C<\000>, C<\040>, or nothing depending on the file organization and
5e12dbfa
PP
1103record format. The VMS::Stdio module provides access to the
1104special fopen() requirements of files with unusual attributes on VMS.
e41182b5
GS
1105
1106TCP/IP stacks are optional on VMS, so socket routines might not be
1107implemented. UDP sockets may not be supported.
1108
016930a6
JM
1109The TCP/IP library support for all current versions of VMS is dynamically
1110loaded if present, so even if the routines are configured, they may
1111return a status indicating that they are not implemented.
1112
e41182b5
GS
1113The value of C<$^O> on OpenVMS is "VMS". To determine the architecture
1114that you are running on without resorting to loading all of C<%Config>
1115you can examine the content of the C<@INC> array like so:
1116
1117 if (grep(/VMS_AXP/, @INC)) {
1118 print "I'm on Alpha!\n";
6ab3f9cb 1119
e41182b5
GS
1120 } elsif (grep(/VMS_VAX/, @INC)) {
1121 print "I'm on VAX!\n";
6ab3f9cb 1122
016930a6
JM
1123 } elsif (grep(/VMS_IA64/, @INC)) {
1124 print "I'm on IA64!\n";
1125
e41182b5
GS
1126 } else {
1127 print "I'm not so sure about where $^O is...\n";
1128 }
1129
016930a6
JM
1130In general, the significant differences should only be if Perl is running
1131on VMS_VAX or one of the 64 bit OpenVMS platforms.
1132
b7df3edc
GS
1133On VMS, perl determines the UTC offset from the C<SYS$TIMEZONE_DIFFERENTIAL>
1134logical name. Although the VMS epoch began at 17-NOV-1858 00:00:00.00,
6ab3f9cb 1135calls to C<localtime> are adjusted to count offsets from
b7df3edc 113601-JAN-1970 00:00:00.00, just like Unix.
6ab3f9cb 1137
e41182b5
GS
1138Also see:
1139
1140=over 4
1141
c997b287
GS
1142=item *
1143
96090e4f 1144F<README.vms> (installed as F<README_vms>), L<perlvms>
c997b287
GS
1145
1146=item *
1147
1089a9e3 1148vmsperl list, vmsperl-subscribe@perl.org
e41182b5 1149
c997b287 1150=item *
e41182b5 1151
500f1b69 1152vmsperl on the web, L<http://www.sidhe.org/vmsperl/index.html>
e41182b5
GS
1153
1154=back
1155
495c5fdc
GP
1156=head2 VOS
1157
10fb90aa
PG
1158Perl on VOS (also known as OpenVOS) is discussed in F<README.vos>
1159in the perl distribution (installed as L<perlvos>). Perl on VOS
1160can accept either VOS- or Unix-style file specifications as in
1161either of the following:
495c5fdc 1162
ea8b8ad2
VP
1163 $ perl -ne "print if /perl_setup/i" >system>notices
1164 $ perl -ne "print if /perl_setup/i" /system/notices
495c5fdc
GP
1165
1166or even a mixture of both as in:
1167
ea8b8ad2 1168 $ perl -ne "print if /perl_setup/i" >system/notices
495c5fdc 1169
b7df3edc 1170Even though VOS allows the slash character to appear in object
495c5fdc 1171names, because the VOS port of Perl interprets it as a pathname
10fb90aa
PG
1172delimiting character, VOS files, directories, or links whose
1173names contain a slash character cannot be processed. Such files
1174must be renamed before they can be processed by Perl.
1175
1176Older releases of VOS (prior to OpenVOS Release 17.0) limit file
1177names to 32 or fewer characters, prohibit file names from
1178starting with a C<-> character, and prohibit file names from
1179containing any character matching C<< tr/ !#%&'()*;<=>?// >>.
1180
1181Newer releases of VOS (OpenVOS Release 17.0 or later) support a
1182feature known as extended names. On these releases, file names
1183can contain up to 255 characters, are prohibited from starting
1184with a C<-> character, and the set of prohibited characters is
1185reduced to any character matching C<< tr/#%*<>?// >>. There are
c69ca1d4 1186restrictions involving spaces and apostrophes: these characters
10fb90aa
PG
1187must not begin or end a name, nor can they immediately precede or
1188follow a period. Additionally, a space must not immediately
1189precede another space or hyphen. Specifically, the following
1190character combinations are prohibited: space-space,
1191space-hyphen, period-space, space-period, period-apostrophe,
1192apostrophe-period, leading or trailing space, and leading or
1193trailing apostrophe. Although an extended file name is limited
1194to 255 characters, a path name is still limited to 256
1195characters.
1196
7d4dfb6d 1197The value of C<$^O> on VOS is "vos". To determine the
10fb90aa
PG
1198architecture that you are running on without resorting to loading
1199all of C<%Config> you can examine the content of the @INC array
1200like so:
495c5fdc 1201
7d4dfb6d 1202 if ($^O =~ /vos/) {
495c5fdc
GP
1203 print "I'm on a Stratus box!\n";
1204 } else {
1205 print "I'm not on a Stratus box!\n";
1206 die;
1207 }
1208
495c5fdc
GP
1209Also see:
1210
1211=over 4
1212
c997b287 1213=item *
495c5fdc 1214
cc07ed0b 1215F<README.vos> (installed as L<perlvos>)
c997b287
GS
1216
1217=item *
1218
1219The VOS mailing list.
495c5fdc 1220
7d4dfb6d
PG
1221There is no specific mailing list for Perl on VOS. You can contact
1222the Stratus Technologies Customer Assistance Center (CAC) for your
1223region, or you can use the contact information located in the
1224distribution files on the Stratus Anonymous FTP site.
495c5fdc 1225
c997b287
GS
1226=item *
1227
7d4dfb6d
PG
1228Stratus Technologies on the web at L<http://www.stratus.com>
1229
1230=item *
1231
1232VOS Open-Source Software on the web at L<http://ftp.stratus.com/pub/vos/vos.html>
495c5fdc
GP
1233
1234=back
1235
e41182b5
GS
1236=head2 EBCDIC Platforms
1237
1238Recent versions of Perl have been ported to platforms such as OS/400 on
d1e3b762
GS
1239AS/400 minicomputers as well as OS/390, VM/ESA, and BS2000 for S/390
1240Mainframes. Such computers use EBCDIC character sets internally (usually
0cc436d0
GS
1241Character Code Set ID 0037 for OS/400 and either 1047 or POSIX-BC for S/390
1242systems). On the mainframe perl currently works under the "Unix system
1243services for OS/390" (formerly known as OpenEdition), VM/ESA OpenEdition, or
1244the BS200 POSIX-BC system (BS2000 is supported in perl 5.6 and greater).
522b859a 1245See L<perlos390> for details. Note that for OS/400 there is also a port of
1bcbdd38 1246Perl 5.8.1/5.10.0 or later to the PASE which is ASCII-based (as opposed to
522b859a 1247ILE which is EBCDIC-based), see L<perlos400>.
e41182b5 1248
7c5ffed3
JH
1249As of R2.5 of USS for OS/390 and Version 2.3 of VM/ESA these Unix
1250sub-systems do not support the C<#!> shebang trick for script invocation.
1251Hence, on OS/390 and VM/ESA perl scripts can be executed with a header
1252similar to the following simple script:
e41182b5
GS
1253
1254 : # use perl
1255 eval 'exec /usr/local/bin/perl -S $0 ${1+"$@"}'
1256 if 0;
1257 #!/usr/local/bin/perl # just a comment really
1258
1259 print "Hello from perl!\n";
1260
d1e3b762
GS
1261OS/390 will support the C<#!> shebang trick in release 2.8 and beyond.
1262Calls to C<system> and backticks can use POSIX shell syntax on all
1263S/390 systems.
1264
b7df3edc 1265On the AS/400, if PERL5 is in your library list, you may need
6ab3f9cb
GS
1266to wrap your perl scripts in a CL procedure to invoke them like so:
1267
1268 BEGIN
1269 CALL PGM(PERL5/PERL) PARM('/QOpenSys/hello.pl')
1270 ENDPGM
1271
1272This will invoke the perl script F<hello.pl> in the root of the
1273QOpenSys file system. On the AS/400 calls to C<system> or backticks
1274must use CL syntax.
1275
e41182b5 1276On these platforms, bear in mind that the EBCDIC character set may have
0a47030a
GS
1277an effect on what happens with some perl functions (such as C<chr>,
1278C<pack>, C<print>, C<printf>, C<ord>, C<sort>, C<sprintf>, C<unpack>), as
1279well as bit-fiddling with ASCII constants using operators like C<^>, C<&>
1280and C<|>, not to mention dealing with socket interfaces to ASCII computers
6ab3f9cb 1281(see L<"Newlines">).
e41182b5 1282
b7df3edc
GS
1283Fortunately, most web servers for the mainframe will correctly
1284translate the C<\n> in the following statement to its ASCII equivalent
043fec90 1285(C<\r> is the same under both Unix and OS/390):
e41182b5
GS
1286
1287 print "Content-type: text/html\r\n\r\n";
1288
d1e3b762 1289The values of C<$^O> on some of these platforms includes:
e41182b5 1290
d1e3b762
GS
1291 uname $^O $Config{'archname'}
1292 --------------------------------------------
1293 OS/390 os390 os390
1294 OS400 os400 os400
1295 POSIX-BC posix-bc BS2000-posix-bc
3c075c7d 1296
e41182b5
GS
1297Some simple tricks for determining if you are running on an EBCDIC
1298platform could include any of the following (perhaps all):
1299
ce7b6f06 1300 if ("\t" eq "\005") { print "EBCDIC may be spoken here!\n"; }
e41182b5
GS
1301
1302 if (ord('A') == 193) { print "EBCDIC may be spoken here!\n"; }
1303
1304 if (chr(169) eq 'z') { print "EBCDIC may be spoken here!\n"; }
1305
b7df3edc 1306One thing you may not want to rely on is the EBCDIC encoding
0a47030a
GS
1307of punctuation characters since these may differ from code page to code
1308page (and once your module or script is rumoured to work with EBCDIC,
1309folks will want it to work with all EBCDIC character sets).
e41182b5
GS
1310
1311Also see:
1312
1313=over 4
1314
c997b287
GS
1315=item *
1316
043fec90 1317L<perlos390>, F<README.os390>, F<perlbs2000>, L<perlebcdic>.
c997b287
GS
1318
1319=item *
e41182b5
GS
1320
1321The perl-mvs@perl.org list is for discussion of porting issues as well as
1322general usage issues for all EBCDIC Perls. Send a message body of
1323"subscribe perl-mvs" to majordomo@perl.org.
1324
7ee27b7c 1325=item *
c997b287
GS
1326
1327AS/400 Perl information at
500f1b69 1328L<http://as400.rochester.ibm.com/>
d1e3b762 1329as well as on CPAN in the F<ports/> directory.
e41182b5
GS
1330
1331=back
1332
b8099c3d
CN
1333=head2 Acorn RISC OS
1334
b7df3edc
GS
1335Because Acorns use ASCII with newlines (C<\n>) in text files as C<\012> like
1336Unix, and because Unix filename emulation is turned on by default,
1337most simple scripts will probably work "out of the box". The native
6ab3f9cb 1338filesystem is modular, and individual filesystems are free to be
0a47030a 1339case-sensitive or insensitive, and are usually case-preserving. Some
b7df3edc 1340native filesystems have name length limits, which file and directory
6ab3f9cb
GS
1341names are silently truncated to fit. Scripts should be aware that the
1342standard filesystem currently has a name length limit of B<10>
1343characters, with up to 77 items in a directory, but other filesystems
0a47030a 1344may not impose such limitations.
b8099c3d
CN
1345
1346Native filenames are of the form
1347
6ab3f9cb 1348 Filesystem#Special_Field::DiskName.$.Directory.Directory.File
dd9f0070 1349
b8099c3d
CN
1350where
1351
1352 Special_Field is not usually present, but may contain . and $ .
1353 Filesystem =~ m|[A-Za-z0-9_]|
1354 DsicName =~ m|[A-Za-z0-9_/]|
1355 $ represents the root directory
1356 . is the path separator
1357 @ is the current directory (per filesystem but machine global)
1358 ^ is the parent directory
1359 Directory and File =~ m|[^\0- "\.\$\%\&:\@\\^\|\177]+|
1360
1361The default filename translation is roughly C<tr|/.|./|;>
1362
6ab3f9cb 1363Note that C<"ADFS::HardDisk.$.File" ne 'ADFS::HardDisk.$.File'> and that
0a47030a
GS
1364the second stage of C<$> interpolation in regular expressions will fall
1365foul of the C<$.> if scripts are not careful.
1366
1367Logical paths specified by system variables containing comma-separated
b7df3edc 1368search lists are also allowed; hence C<System:Modules> is a valid
0a47030a 1369filename, and the filesystem will prefix C<Modules> with each section of
6ab3f9cb 1370C<System$Path> until a name is made that points to an object on disk.
b7df3edc 1371Writing to a new file C<System:Modules> would be allowed only if
0a47030a
GS
1372C<System$Path> contains a single item list. The filesystem will also
1373expand system variables in filenames if enclosed in angle brackets, so
c47ff5f1 1374C<< <System$Dir>.Modules >> would look for the file
0a47030a 1375S<C<$ENV{'System$Dir'} . 'Modules'>>. The obvious implication of this is
c47ff5f1 1376that B<fully qualified filenames can start with C<< <> >>> and should
0a47030a 1377be protected when C<open> is used for input.
b8099c3d
CN
1378
1379Because C<.> was in use as a directory separator and filenames could not
1380be assumed to be unique after 10 characters, Acorn implemented the C
1381compiler to strip the trailing C<.c> C<.h> C<.s> and C<.o> suffix from
1382filenames specified in source code and store the respective files in
b7df3edc 1383subdirectories named after the suffix. Hence files are translated:
b8099c3d
CN
1384
1385 foo.h h.foo
1386 C:foo.h C:h.foo (logical path variable)
1387 sys/os.h sys.h.os (C compiler groks Unix-speak)
1388 10charname.c c.10charname
1389 10charname.o o.10charname
1390 11charname_.c c.11charname (assuming filesystem truncates at 10)
1391
1392The Unix emulation library's translation of filenames to native assumes
b7df3edc
GS
1393that this sort of translation is required, and it allows a user-defined list
1394of known suffixes that it will transpose in this fashion. This may
92863ac5
KW
1395seem transparent, but consider that with these rules F<foo/bar/baz.h>
1396and F<foo/bar/h/baz> both map to F<foo.bar.h.baz>, and that C<readdir> and
0a47030a 1397C<glob> cannot and do not attempt to emulate the reverse mapping. Other
6ab3f9cb 1398C<.>'s in filenames are translated to C</>.
0a47030a 1399
b7df3edc 1400As implied above, the environment accessed through C<%ENV> is global, and
0a47030a 1401the convention is that program specific environment variables are of the
6ab3f9cb
GS
1402form C<Program$Name>. Each filesystem maintains a current directory,
1403and the current filesystem's current directory is the B<global> current
b7df3edc
GS
1404directory. Consequently, sociable programs don't change the current
1405directory but rely on full pathnames, and programs (and Makefiles) cannot
0a47030a
GS
1406assume that they can spawn a child process which can change the current
1407directory without affecting its parent (and everyone else for that
1408matter).
1409
b7df3edc
GS
1410Because native operating system filehandles are global and are currently
1411allocated down from 255, with 0 being a reserved value, the Unix emulation
0a47030a
GS
1412library emulates Unix filehandles. Consequently, you can't rely on
1413passing C<STDIN>, C<STDOUT>, or C<STDERR> to your children.
1414
1415The desire of users to express filenames of the form
c47ff5f1 1416C<< <Foo$Dir>.Bar >> on the command line unquoted causes problems,
0a47030a 1417too: C<``> command output capture has to perform a guessing game. It
c47ff5f1 1418assumes that a string C<< <[^<>]+\$[^<>]> >> is a
0a47030a 1419reference to an environment variable, whereas anything else involving
c47ff5f1 1420C<< < >> or C<< > >> is redirection, and generally manages to be 99%
0a47030a
GS
1421right. Of course, the problem remains that scripts cannot rely on any
1422Unix tools being available, or that any tools found have Unix-like command
1423line arguments.
1424
b7df3edc
GS
1425Extensions and XS are, in theory, buildable by anyone using free
1426tools. In practice, many don't, as users of the Acorn platform are
1427used to binary distributions. MakeMaker does run, but no available
1428make currently copes with MakeMaker's makefiles; even if and when
1429this should be fixed, the lack of a Unix-like shell will cause
1430problems with makefile rules, especially lines of the form C<cd
1431sdbm && make all>, and anything using quoting.
b8099c3d
CN
1432
1433"S<RISC OS>" is the proper name for the operating system, but the value
1434in C<$^O> is "riscos" (because we don't like shouting).
1435
e41182b5
GS
1436=head2 Other perls
1437
b7df3edc 1438Perl has been ported to many platforms that do not fit into any of
b6c36746 1439the categories listed above. Some, such as AmigaOS,
cd86ed9d
JV
1440QNX, Plan 9, and VOS, have been well-integrated into the standard
1441Perl source code kit. You may need to see the F<ports/> directory
1442on CPAN for information, and possibly binaries, for the likes of:
1443aos, Atari ST, lynxos, riscos, Novell Netware, Tandem Guardian,
1444I<etc.> (Yes, we know that some of these OSes may fall under the
1445Unix category, but we are not a standards body.)
e41182b5 1446
d1e3b762
GS
1447Some approximate operating system names and their C<$^O> values
1448in the "OTHER" category include:
1449
1450 OS $^O $Config{'archname'}
1451 ------------------------------------------
1452 Amiga DOS amigaos m68k-amigos
d1e3b762 1453
e41182b5
GS
1454See also:
1455
1456=over 4
1457
c997b287
GS
1458=item *
1459
1460Amiga, F<README.amiga> (installed as L<perlamiga>).
1461
1462=item *
d1e3b762 1463
6ab3f9cb 1464A free perl5-based PERL.NLM for Novell Netware is available in
500f1b69 1465precompiled binary and source code form from L<http://www.novell.com/>
6ab3f9cb 1466as well as from CPAN.
e41182b5 1467
13a2d996 1468=item *
c997b287 1469
e6f03d26 1470S<Plan 9>, F<README.plan9>
d1e3b762 1471
e41182b5
GS
1472=back
1473
e41182b5
GS
1474=head1 FUNCTION IMPLEMENTATIONS
1475
b7df3edc
GS
1476Listed below are functions that are either completely unimplemented
1477or else have been implemented differently on various platforms.
1478Following each description will be, in parentheses, a list of
1479platforms that the description applies to.
e41182b5 1480
b7df3edc
GS
1481The list may well be incomplete, or even wrong in some places. When
1482in doubt, consult the platform-specific README files in the Perl
1483source distribution, and any other documentation resources accompanying
1484a given port.
e41182b5 1485
0a47030a 1486Be aware, moreover, that even among Unix-ish systems there are variations.
e41182b5 1487
b7df3edc
GS
1488For many functions, you can also query C<%Config>, exported by
1489default from the Config module. For example, to check whether the
1490platform has the C<lstat> call, check C<$Config{d_lstat}>. See
1491L<Config> for a full description of available variables.
e41182b5
GS
1492
1493=head2 Alphabetical Listing of Perl Functions
1494
1495=over 8
1496
e41182b5
GS
1497=item -X
1498
038ae9a4
SH
1499C<-w> only inspects the read-only file attribute (FILE_ATTRIBUTE_READONLY),
1500which determines whether the directory can be deleted, not whether it can
1501be written to. Directories always have read and write access unless denied
1502by discretionary access control lists (DACLs). (S<Win32>)
1503
b7df3edc
GS
1504C<-r>, C<-w>, C<-x>, and C<-o> tell whether the file is accessible,
1505which may not reflect UIC-based file protections. (VMS)
e41182b5 1506
b8099c3d
CN
1507C<-s> by name on an open file will return the space reserved on disk,
1508rather than the current extent. C<-s> on an open filehandle returns the
b7df3edc 1509current size. (S<RISC OS>)
b8099c3d 1510
e41182b5 1511C<-R>, C<-W>, C<-X>, C<-O> are indistinguishable from C<-r>, C<-w>,
204ad8d5 1512C<-x>, C<-o>. (Win32, VMS, S<RISC OS>)
e41182b5 1513
287a962e 1514C<-g>, C<-k>, C<-l>, C<-u>, C<-A> are not particularly meaningful.
b8099c3d 1515(Win32, VMS, S<RISC OS>)
e41182b5 1516
287a962e
JD
1517C<-p> is not particularly meaningful. (VMS, S<RISC OS>)
1518
e41182b5
GS
1519C<-d> is true if passed a device spec without an explicit directory.
1520(VMS)
1521
e41182b5 1522C<-x> (or C<-X>) determine if a file ends in one of the executable
b7df3edc 1523suffixes. C<-S> is meaningless. (Win32)
e41182b5 1524
b8099c3d
CN
1525C<-x> (or C<-X>) determine if a file has an executable file type.
1526(S<RISC OS>)
1527
aca72608
JD
1528=item alarm
1529
1530Emulated using timers that must be explicitly polled whenever Perl
1531wants to dispatch "safe signals" and therefore cannot interrupt
1532blocking system calls. (Win32)
1533
47cd99a4 1534=item atan2
519bc777
RGS
1535
1536Due to issues with various CPUs, math libraries, compilers, and standards,
1537results for C<atan2()> may vary depending on any combination of the above.
1538Perl attempts to conform to the Open Group/IEEE standards for the results
1539returned from C<atan2()>, but cannot force the issue if the system Perl is
1540run on does not allow it. (Tru64, HP-UX 10.20)
1541
1542The current version of the standards for C<atan2()> is available at
1543L<http://www.opengroup.org/onlinepubs/009695399/functions/atan2.html>.
1544
47cd99a4 1545=item binmode
e41182b5 1546
204ad8d5 1547Meaningless. (S<RISC OS>)
e41182b5
GS
1548
1549Reopens file and restores pointer; if function fails, underlying
1550filehandle may be closed, or pointer may be in a different position.
1551(VMS)
1552
1553The value returned by C<tell> may be affected after the call, and
1554the filehandle may be flushed. (Win32)
1555
47cd99a4 1556=item chmod
e41182b5 1557
e41182b5
GS
1558Only good for changing "owner" read-write access, "group", and "other"
1559bits are meaningless. (Win32)
1560
b8099c3d
CN
1561Only good for changing "owner" and "other" read-write access. (S<RISC OS>)
1562
495c5fdc
GP
1563Access permissions are mapped onto VOS access-control list changes. (VOS)
1564
4e51f8e4 1565The actual permissions set depend on the value of the C<CYGWIN>
789f0d36 1566in the SYSTEM environment settings. (Cygwin)
4e51f8e4 1567
47cd99a4 1568=item chown
e41182b5 1569
204ad8d5 1570Not implemented. (Win32, S<Plan 9>, S<RISC OS>)
e41182b5
GS
1571
1572Does nothing, but won't fail. (Win32)
1573
3fd80bd6
PG
1574A little funky, because VOS's notion of ownership is a little funky (VOS).
1575
e41182b5
GS
1576=item chroot
1577
043fec90 1578Not implemented. (Win32, VMS, S<Plan 9>, S<RISC OS>, VOS)
e41182b5 1579
47cd99a4 1580=item crypt
e41182b5
GS
1581
1582May not be available if library or source was not provided when building
b8099c3d 1583perl. (Win32)
e41182b5 1584
47cd99a4 1585=item dbmclose
e41182b5 1586
e6f03d26 1587Not implemented. (VMS, S<Plan 9>, VOS)
e41182b5 1588
47cd99a4 1589=item dbmopen
e41182b5 1590
e6f03d26 1591Not implemented. (VMS, S<Plan 9>, VOS)
e41182b5 1592
47cd99a4 1593=item dump
e41182b5 1594
204ad8d5 1595Not useful. (S<RISC OS>)
e41182b5 1596
84d78eb7 1597Not supported. (Cygwin, Win32)
e41182b5 1598
b8099c3d 1599Invokes VMS debugger. (VMS)
e41182b5 1600
47cd99a4 1601=item exec
e41182b5 1602
0f897271
GS
1603Does not automatically flush output handles on some platforms.
1604(SunOS, Solaris, HP-UX)
1605
af8bb25a
FC
1606Not supported. (Symbian OS)
1607
fe12c0e8
MS
1608=item exit
1609
e1020413 1610Emulates Unix exit() (which considers C<exit 1> to indicate an error) by
fe12c0e8
MS
1611mapping the C<1> to SS$_ABORT (C<44>). This behavior may be overridden
1612with the pragma C<use vmsish 'exit'>. As with the CRTL's exit()
1613function, C<exit 0> is also mapped to an exit status of SS$_NORMAL
1614(C<1>); this mapping cannot be overridden. Any other argument to exit()
016930a6
JM
1615is used directly as Perl's exit status. On VMS, unless the future
1616POSIX_EXIT mode is enabled, the exit code should always be a valid
1617VMS exit code and not a generic number. When the POSIX_EXIT mode is
1618enabled, a generic number will be encoded in a method compatible with
1619the C library _POSIX_EXIT macro so that it can be decoded by other
1620programs, particularly ones written in C, like the GNV package. (VMS)
fe12c0e8 1621
bef2c191
RB
1622C<exit()> resets file pointers, which is a problem when called
1623from a child process (created by C<fork()>) in C<BEGIN>.
1624A workaround is to use C<POSIX::_exit>. (Solaris)
1625
1626 exit unless $Config{archname} =~ /\bsolaris\b/;
1627 require POSIX and POSIX::_exit(0);
1628
47cd99a4 1629=item fcntl
e41182b5 1630
016930a6 1631Not implemented. (Win32)
6a065175 1632
016930a6 1633Some functions available based on the version of VMS. (VMS)
e41182b5 1634
47cd99a4 1635=item flock
e41182b5 1636
204ad8d5 1637Not implemented (VMS, S<RISC OS>, VOS).
e41182b5 1638
e41182b5
GS
1639=item fork
1640
043fec90 1641Not implemented. (AmigaOS, S<RISC OS>, VMS)
0f897271
GS
1642
1643Emulated using multiple interpreters. See L<perlfork>. (Win32)
1644
1645Does not automatically flush output handles on some platforms.
1646(SunOS, Solaris, HP-UX)
e41182b5
GS
1647
1648=item getlogin
1649
204ad8d5 1650Not implemented. (S<RISC OS>)
e41182b5 1651
47cd99a4 1652=item getpgrp
e41182b5 1653
204ad8d5 1654Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5
GS
1655
1656=item getppid
1657
204ad8d5 1658Not implemented. (Win32, S<RISC OS>)
e41182b5 1659
47cd99a4 1660=item getpriority
e41182b5 1661
043fec90 1662Not implemented. (Win32, VMS, S<RISC OS>, VOS)
e41182b5 1663
47cd99a4 1664=item getpwnam
e41182b5 1665
204ad8d5 1666Not implemented. (Win32)
e41182b5 1667
b8099c3d
CN
1668Not useful. (S<RISC OS>)
1669
47cd99a4 1670=item getgrnam
e41182b5 1671
204ad8d5 1672Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5 1673
47cd99a4 1674=item getnetbyname
e41182b5 1675
204ad8d5 1676Not implemented. (Win32, S<Plan 9>)
e41182b5 1677
47cd99a4 1678=item getpwuid
e41182b5 1679
204ad8d5 1680Not implemented. (Win32)
e41182b5 1681
b8099c3d
CN
1682Not useful. (S<RISC OS>)
1683
47cd99a4 1684=item getgrgid
e41182b5 1685
204ad8d5 1686Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5 1687
47cd99a4 1688=item getnetbyaddr
e41182b5 1689
204ad8d5 1690Not implemented. (Win32, S<Plan 9>)
e41182b5 1691
47cd99a4 1692=item getprotobynumber
e41182b5 1693
47cd99a4 1694=item getservbyport
e41182b5 1695
e41182b5
GS
1696=item getpwent
1697
043fec90 1698Not implemented. (Win32)
e41182b5
GS
1699
1700=item getgrent
1701
043fec90 1702Not implemented. (Win32, VMS)
e41182b5 1703
ef5a6dd7
JH
1704=item gethostbyname
1705
1706C<gethostbyname('localhost')> does not work everywhere: you may have
204ad8d5 1707to use C<gethostbyname('127.0.0.1')>. (S<Irix 5>)
ef5a6dd7 1708
e41182b5
GS
1709=item gethostent
1710
204ad8d5 1711Not implemented. (Win32)
e41182b5
GS
1712
1713=item getnetent
1714
204ad8d5 1715Not implemented. (Win32, S<Plan 9>)
e41182b5
GS
1716
1717=item getprotoent
1718
204ad8d5 1719Not implemented. (Win32, S<Plan 9>)
e41182b5
GS
1720
1721=item getservent
1722
e6f03d26 1723Not implemented. (Win32, S<Plan 9>)
e41182b5 1724
47cd99a4 1725=item sethostent
e41182b5 1726
204ad8d5 1727Not implemented. (Win32, S<Plan 9>, S<RISC OS>)
e41182b5 1728
47cd99a4 1729=item setnetent
e41182b5 1730
204ad8d5 1731Not implemented. (Win32, S<Plan 9>, S<RISC OS>)
e41182b5 1732
47cd99a4 1733=item setprotoent
e41182b5 1734
204ad8d5 1735Not implemented. (Win32, S<Plan 9>, S<RISC OS>)
e41182b5 1736
47cd99a4 1737=item setservent
e41182b5 1738
e6f03d26 1739Not implemented. (S<Plan 9>, Win32, S<RISC OS>)
e41182b5
GS
1740
1741=item endpwent
1742
b5afd346 1743Not implemented. (Win32)
e41182b5
GS
1744
1745=item endgrent
1746
b5afd346 1747Not implemented. (S<RISC OS>, VMS, Win32)
e41182b5
GS
1748
1749=item endhostent
1750
204ad8d5 1751Not implemented. (Win32)
e41182b5
GS
1752
1753=item endnetent
1754
204ad8d5 1755Not implemented. (Win32, S<Plan 9>)
e41182b5
GS
1756
1757=item endprotoent
1758
204ad8d5 1759Not implemented. (Win32, S<Plan 9>)
e41182b5
GS
1760
1761=item endservent
1762
e6f03d26 1763Not implemented. (S<Plan 9>, Win32)
e41182b5
GS
1764
1765=item getsockopt SOCKET,LEVEL,OPTNAME
1766
e6f03d26 1767Not implemented. (S<Plan 9>)
e41182b5 1768
e41182b5
GS
1769=item glob
1770
63f87e49
GS
1771This operator is implemented via the File::Glob extension on most
1772platforms. See L<File::Glob> for portability information.
b8099c3d 1773
62aa5637
MS
1774=item gmtime
1775
461d5a49
MS
1776In theory, gmtime() is reliable from -2**63 to 2**63-1. However,
1777because work arounds in the implementation use floating point numbers,
1778it will become inaccurate as the time gets larger. This is a bug and
1779will be fixed in the future.
62aa5637 1780
10fb90aa
PG
1781On VOS, time values are 32-bit quantities.
1782
e41182b5
GS
1783=item ioctl FILEHANDLE,FUNCTION,SCALAR
1784
1785Not implemented. (VMS)
1786
1787Available only for socket handles, and it does what the ioctlsocket() call
1788in the Winsock API does. (Win32)
1789
b8099c3d
CN
1790Available only for socket handles. (S<RISC OS>)
1791
47cd99a4 1792=item kill
e41182b5 1793
862b5365 1794Not implemented, hence not useful for taint checking. (S<RISC OS>)
e41182b5 1795
63f87e49
GS
1796C<kill()> doesn't have the semantics of C<raise()>, i.e. it doesn't send
1797a signal to the identified process like it does on Unix platforms.
1798Instead C<kill($sig, $pid)> terminates the process identified by $pid,
1799and makes it exit immediately with exit status $sig. As in Unix, if
1800$sig is 0 and the specified process exists, it returns true without
1801actually terminating it. (Win32)
e41182b5 1802
d0302514
JD
1803C<kill(-9, $pid)> will terminate the process specified by $pid and
1804recursively all child processes owned by it. This is different from
1805the Unix semantics, where the signal will be delivered to all
1806processes in the same process group as the process specified by
1807$pid. (Win32)
1808
016930a6
JM
1809Is not supported for process identification number of 0 or negative
1810numbers. (VMS)
1811
47cd99a4 1812=item link
e41182b5 1813
b5afd346 1814Not implemented. (S<RISC OS>, VOS)
e41182b5 1815
433acd8a
JH
1816Link count not updated because hard links are not quite that hard
1817(They are sort of half-way between hard and soft links). (AmigaOS)
1818
63d6c08b
JD
1819Hard links are implemented on Win32 under NTFS only. They are
1820natively supported on Windows 2000 and later. On Windows NT they
1821are implemented using the Windows POSIX subsystem support and the
1822Perl process will need Administrator or Backup Operator privileges
1823to create hard links.
a3dfe201 1824
016930a6
JM
1825Available on 64 bit OpenVMS 8.2 and later. (VMS)
1826
62aa5637
MS
1827=item localtime
1828
a61fc69c 1829localtime() has the same range as L</gmtime>, but because time zone
dc164757
MS
1830rules change its accuracy for historical and future times may degrade
1831but usually by no more than an hour.
62aa5637 1832
e41182b5
GS
1833=item lstat
1834
016930a6 1835Not implemented. (S<RISC OS>)
e41182b5 1836
63f87e49 1837Return values (especially for device and inode) may be bogus. (Win32)
e41182b5 1838
47cd99a4 1839=item msgctl
e41182b5 1840
47cd99a4 1841=item msgget
e41182b5 1842
47cd99a4 1843=item msgsnd
e41182b5 1844
47cd99a4 1845=item msgrcv
e41182b5 1846
204ad8d5 1847Not implemented. (Win32, VMS, S<Plan 9>, S<RISC OS>, VOS)
e41182b5 1848
47cd99a4 1849=item open
e41182b5 1850
204ad8d5 1851open to C<|-> and C<-|> are unsupported. (Win32, S<RISC OS>)
e41182b5 1852
0f897271
GS
1853Opening a process does not automatically flush output handles on some
1854platforms. (SunOS, Solaris, HP-UX)
1855
e41182b5
GS
1856=item readlink
1857
b8099c3d 1858Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5 1859
47cd99a4 1860=item rename
c9b2b9d4
SS
1861
1862Can't move directories between directories on different logical volumes. (Win32)
1863
3ba4b5c1
JD
1864=item rewinddir
1865
1866Will not cause readdir() to re-read the directory stream. The entries
1867already read before the rewinddir() call will just be returned again
1868from a cache buffer. (Win32)
1869
47cd99a4 1870=item select
e41182b5 1871
689c5c24 1872Only implemented on sockets. (Win32, VMS)
e41182b5 1873
b8099c3d
CN
1874Only reliable on sockets. (S<RISC OS>)
1875
76e05f0b 1876Note that the C<select FILEHANDLE> form is generally portable.
63f87e49 1877
47cd99a4 1878=item semctl
e41182b5 1879
47cd99a4 1880=item semget
e41182b5 1881
47cd99a4 1882=item semop
e41182b5 1883
10fb90aa 1884Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5 1885
a3dfe201
GS
1886=item setgrent
1887
b5afd346 1888Not implemented. (VMS, Win32, S<RISC OS>)
a3dfe201 1889
47cd99a4 1890=item setpgrp
e41182b5 1891
204ad8d5 1892Not implemented. (Win32, VMS, S<RISC OS>, VOS)
e41182b5 1893
47cd99a4 1894=item setpriority
e41182b5 1895
204ad8d5 1896Not implemented. (Win32, VMS, S<RISC OS>, VOS)
e41182b5 1897
a3dfe201
GS
1898=item setpwent
1899
b5afd346 1900Not implemented. (Win32, S<RISC OS>)
a3dfe201 1901
47cd99a4 1902=item setsockopt
e41182b5 1903
e6f03d26 1904Not implemented. (S<Plan 9>)
e41182b5 1905
47cd99a4 1906=item shmctl
e41182b5 1907
47cd99a4 1908=item shmget
e41182b5 1909
47cd99a4 1910=item shmread
e41182b5 1911
47cd99a4 1912=item shmwrite
e41182b5 1913
7d4dfb6d 1914Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5 1915
001e9f89
DD
1916=item sleep
1917
3cd50447
SH
1918Emulated using synchronization functions such that it can be
1919interrupted by alarm(), and limited to a maximum of 4294967 seconds,
1920approximately 49 days. (Win32)
001e9f89 1921
47cd99a4 1922=item sockatmark
80cbd5ad
JH
1923
1924A relatively recent addition to socket functions, may not
e1020413 1925be implemented even in Unix platforms.
80cbd5ad 1926
47cd99a4 1927=item socketpair
e41182b5 1928
043fec90 1929Not implemented. (S<RISC OS>)
10fb90aa 1930
016930a6 1931Available on 64 bit OpenVMS 8.2 and later. (VMS)
e41182b5 1932
e41182b5
GS
1933=item stat
1934
d62e1b7f
JH
1935Platforms that do not have rdev, blksize, or blocks will return these
1936as '', so numeric comparison or manipulation of these fields may cause
1937'not numeric' warnings.
1938
3f1f789b 1939ctime not supported on UFS (S<Mac OS X>).
e41182b5 1940
95a3fe12
MS
1941ctime is creation time instead of inode change time (Win32).
1942
e41182b5
GS
1943device and inode are not meaningful. (Win32)
1944
1945device and inode are not necessarily reliable. (VMS)
1946
b8099c3d
CN
1947mtime, atime and ctime all return the last modification time. Device and
1948inode are not necessarily reliable. (S<RISC OS>)
1949
d62e1b7f
JH
1950dev, rdev, blksize, and blocks are not available. inode is not
1951meaningful and will differ between stat calls on the same file. (os2)
1952
73e9292c
JH
1953some versions of cygwin when doing a stat("foo") and if not finding it
1954may then attempt to stat("foo.exe") (Cygwin)
1955
1fafdf34
JD
1956On Win32 stat() needs to open the file to determine the link count
1957and update attributes that may have been changed through hard links.
1958Setting ${^WIN32_SLOPPY_STAT} to a true value speeds up stat() by
1959not performing this operation. (Win32)
1960
47cd99a4 1961=item symlink
e41182b5 1962
c73b03b7
JM
1963Not implemented. (Win32, S<RISC OS>)
1964
1965Implemented on 64 bit VMS 8.3. VMS requires the symbolic link to be in Unix
1966syntax if it is intended to resolve to a valid path.
e41182b5 1967
47cd99a4 1968=item syscall
e41182b5 1969
043fec90 1970Not implemented. (Win32, VMS, S<RISC OS>, VOS)
e41182b5 1971
47cd99a4 1972=item sysopen
f34d0673 1973
dd9f0070 1974The traditional "0", "1", and "2" MODEs are implemented with different
322422de
GS
1975numeric values on some systems. The flags exported by C<Fcntl>
1976(O_RDONLY, O_WRONLY, O_RDWR) should work everywhere though. (S<Mac
043fec90 1977OS>, OS/390)
f34d0673 1978
47cd99a4 1979=item system
e41182b5 1980
e41182b5 1981As an optimization, may not call the command shell specified in
b7df3edc 1982C<$ENV{PERL5SHELL}>. C<system(1, @args)> spawns an external
e41182b5
GS
1983process and immediately returns its process designator, without
1984waiting for it to terminate. Return value may be used subsequently
63f87e49
GS
1985in C<wait> or C<waitpid>. Failure to spawn() a subprocess is indicated
1986by setting $? to "255 << 8". C<$?> is set in a way compatible with
1987Unix (i.e. the exitstatus of the subprocess is obtained by "$? >> 8",
1988as described in the documentation). (Win32)
e41182b5 1989
b8099c3d
CN
1990There is no shell to process metacharacters, and the native standard is
1991to pass a command line terminated by "\n" "\r" or "\0" to the spawned
c47ff5f1 1992program. Redirection such as C<< > foo >> is performed (if at all) by
b8099c3d
CN
1993the run time library of the spawned program. C<system> I<list> will call
1994the Unix emulation library's C<exec> emulation, which attempts to provide
1995emulation of the stdin, stdout, stderr in force in the parent, providing
1996the child program uses a compatible version of the emulation library.
1997I<scalar> will call the native command line direct and no such emulation
1998of a child Unix program will exists. Mileage B<will> vary. (S<RISC OS>)
1999
0f897271
GS
2000Does not automatically flush output handles on some platforms.
2001(SunOS, Solaris, HP-UX)
2002
9bc98430
CB
2003The return value is POSIX-like (shifted up by 8 bits), which only allows
2004room for a made-up value derived from the severity bits of the native
200532-bit condition code (unless overridden by C<use vmsish 'status'>).
016930a6
JM
2006If the native condition code is one that has a POSIX value encoded, the
2007POSIX value will be decoded to extract the expected exit value.
9bc98430
CB
2008For more details see L<perlvms/$?>. (VMS)
2009
e41182b5
GS
2010=item times
2011
63f87e49
GS
2012"cumulative" times will be bogus. On anything other than Windows NT
2013or Windows 2000, "system" time will be bogus, and "user" time is
2014actually the time returned by the clock() function in the C runtime
2015library. (Win32)
e41182b5 2016
b8099c3d
CN
2017Not useful. (S<RISC OS>)
2018
47cd99a4 2019=item truncate
e41182b5 2020
6d738113 2021Not implemented. (Older versions of VMS)
e41182b5 2022
3fd80bd6 2023Truncation to same-or-shorter lengths only. (VOS)
495c5fdc 2024
4cfdb94f 2025If a FILEHANDLE is supplied, it must be writable and opened in append
e71a7dc8 2026mode (i.e., use C<<< open(FH, '>>filename') >>>
4cfdb94f
GS
2027or C<sysopen(FH,...,O_APPEND|O_RDWR)>. If a filename is supplied, it
2028should not be held open elsewhere. (Win32)
2029
e41182b5
GS
2030=item umask
2031
1bcbdd38 2032Returns undef where unavailable.
e41182b5 2033
b7df3edc
GS
2034C<umask> works but the correct permissions are set only when the file
2035is finally closed. (AmigaOS)
433acd8a 2036
47cd99a4 2037=item utime
e41182b5 2038
b6c36746 2039Only the modification time is updated. (VMS, S<RISC OS>)
e41182b5 2040
322422de
GS
2041May not behave as expected. Behavior depends on the C runtime
2042library's implementation of utime(), and the filesystem being
2043used. The FAT filesystem typically does not support an "access
2044time" field, and it may limit timestamps to a granularity of
2045two seconds. (Win32)
e41182b5
GS
2046
2047=item wait
2048
47cd99a4 2049=item waitpid
e41182b5 2050
e41182b5 2051Can only be applied to process handles returned for processes spawned
a6f858fb 2052using C<system(1, ...)> or pseudo processes created with C<fork()>. (Win32)
e41182b5 2053
b8099c3d
CN
2054Not useful. (S<RISC OS>)
2055
e41182b5
GS
2056=back
2057
2058
7c35b6af 2059=head1 Supported Platforms
ba58ab26 2060
7c35b6af
RGS
2061The following platforms are known to build Perl 5.12 (as of April 2010,
2062its release date) from the standard source code distribution available
500f1b69 2063at L<http://www.cpan.org/src>
bb377ba2 2064
bb377ba2
JV
2065=over
2066
2067=item Linux (x86, ARM, IA64)
2068
e0d9a2c8 2069=item HP-UX
bb377ba2
JV
2070
2071=item AIX
2072
2073=item Win32
2074
2075=over
2076
2077=item Windows 2000
2078
2079=item Windows XP
2080
2081=item Windows Server 2003
2082
2083=item Windows Vista
2084
2085=item Windows Server 2008
2086
3b665c47
JD
2087=item Windows 7
2088
bb377ba2
JV
2089=back
2090
2d9ede6e
JH
2091=item Cygwin
2092
bb377ba2
JV
2093=item Solaris (x86, SPARC)
2094
1b0ab010
JV
2095=item OpenVMS
2096
2097=over
2098
2099=item Alpha (7.2 and later)
2100
2101=item I64 (8.2 and later)
2102
2103=back
bb377ba2
JV
2104
2105=item Symbian
2106
2107=item NetBSD
2108
2109=item FreeBSD
2110
2d8e9a35
CBW
2111=item Debian GNU/kFreeBSD
2112
bb377ba2
JV
2113=item Haiku
2114
2115=item Irix (6.5. What else?)
2116
2117=item OpenBSD
2118
2119=item Dragonfly BSD
2120
b60fc215
CBW
2121=item Midnight BSD
2122
a62bfce3
CBW
2123=item QNX Neutrino RTOS (6.5.0)
2124
bb377ba2
JV
2125=item MirOS BSD
2126
7d4dfb6d
PG
2127=item Stratus OpenVOS (17.0 or later)
2128
bb377ba2
JV
2129Caveats:
2130
2131=over
2132
2133=item time_t issues that may or may not be fixed
2134
2135=back
2136
bb377ba2
JV
2137=item Symbian (Series 60 v3, 3.2 and 5 - what else?)
2138
10fb90aa 2139=item Stratus VOS / OpenVOS
bb377ba2
JV
2140
2141=item AIX
2142
2143=back
2144
8cbe99e5 2145=head1 EOL Platforms (Perl 5.14)
bb377ba2
JV
2146
2147The following platforms were supported by a previous version of
2148Perl but have been officially removed from Perl's source code
2149as of 5.12:
2150
2151=over
2152
2153=item Atari MiNT
2154
2155=item Apollo Domain/OS
2156
2157=item Apple Mac OS 8/9
2158
2159=item Tenon Machten
2160
2161=back
2162
8cbe99e5
JD
2163The following platforms were supported up to 5.10. They may still
2164have worked in 5.12, but supporting code has been removed for 5.14:
bb377ba2
JV
2165
2166=over
2167
2168=item Windows 95
2169
2170=item Windows 98
2171
2172=item Windows ME
2173
2174=item Windows NT4
2175
2176=back
2177
2178=head1 Supported Platforms (Perl 5.8)
2179
2180As of July 2002 (the Perl release 5.8.0), the following platforms were
cec2c193 2181able to build Perl from the standard source code distribution
500f1b69 2182available at L<http://www.cpan.org/src/>
cec2c193
JH
2183
2184 AIX
2185 BeOS
6f683aa2 2186 BSD/OS (BSDi)
cec2c193 2187 Cygwin
ea297d26 2188 DG/UX
811b48f2 2189 DOS DJGPP 1)
cec2c193
JH
2190 DYNIX/ptx
2191 EPOC R5
2192 FreeBSD
6f683aa2 2193 HI-UXMPP (Hitachi) (5.8.0 worked but we didn't know it)
cec2c193
JH
2194 HP-UX
2195 IRIX
2196 Linux
8939ba94 2197 Mac OS Classic
6f683aa2 2198 Mac OS X (Darwin)
cec2c193
JH
2199 MPE/iX
2200 NetBSD
2201 NetWare
2202 NonStop-UX
6f683aa2 2203 ReliantUNIX (formerly SINIX)
cec2c193 2204 OpenBSD
6f683aa2 2205 OpenVMS (formerly VMS)
3ebac25b 2206 Open UNIX (Unixware) (since Perl 5.8.1/5.9.0)
cec2c193 2207 OS/2
522b859a 2208 OS/400 (using the PASE) (since Perl 5.8.1/5.9.0)
70de81db 2209 PowerUX
6f683aa2 2210 POSIX-BC (formerly BS2000)
cec2c193
JH
2211 QNX
2212 Solaris
70de81db 2213 SunOS 4
6f683aa2
JH
2214 SUPER-UX (NEC)
2215 Tru64 UNIX (formerly DEC OSF/1, Digital UNIX)
cec2c193
JH
2216 UNICOS
2217 UNICOS/mk
2218 UTS
7d4dfb6d 2219 VOS / OpenVOS
811b48f2 2220 Win95/98/ME/2K/XP 2)
c40b5d1d 2221 WinCE
6f683aa2 2222 z/OS (formerly OS/390)
cec2c193 2223 VM/ESA
ba58ab26 2224
811b48f2
JH
2225 1) in DOS mode either the DOS or OS/2 ports can be used
2226 2) compilers: Borland, MinGW (GCC), VC6
cec2c193 2227
c40b5d1d 2228The following platforms worked with the previous releases (5.6 and
cec2c193
JH
22295.7), but we did not manage either to fix or to test these in time
2230for the 5.8.0 release. There is a very good chance that many of these
70de81db 2231will work fine with the 5.8.0.
cec2c193 2232
8da2b1be 2233 BSD/OS
cec2c193
JH
2234 DomainOS
2235 Hurd
2236 LynxOS
2237 MachTen
2238 PowerMAX
2239 SCO SV
cec2c193
JH
2240 SVR4
2241 Unixware
2242 Windows 3.1
ba58ab26 2243
70de81db
JH
2244Known to be broken for 5.8.0 (but 5.6.1 and 5.7.2 can be used):
2245
2246 AmigaOS
2247
ba58ab26 2248The following platforms have been known to build Perl from source in
fd46a41b
JH
2249the past (5.005_03 and earlier), but we haven't been able to verify
2250their status for the current release, either because the
2251hardware/software platforms are rare or because we don't have an
2252active champion on these platforms--or both. They used to work,
2253though, so go ahead and try compiling them, and let perlbug@perl.org
2254of any trouble.
ba58ab26 2255
cec2c193
JH
2256 3b1
2257 A/UX
cec2c193
JH
2258 ConvexOS
2259 CX/UX
2260 DC/OSx
2261 DDE SMES
2262 DOS EMX
2263 Dynix
2264 EP/IX
2265 ESIX
2266 FPS
2267 GENIX
2268 Greenhills
2269 ISC
2270 MachTen 68k
cec2c193
JH
2271 MPC
2272 NEWS-OS
2273 NextSTEP
2274 OpenSTEP
2275 Opus
2276 Plan 9
cec2c193 2277 RISC/os
8da2b1be 2278 SCO ODT/OSR
cec2c193
JH
2279 Stellar
2280 SVR2
2281 TI1500
2282 TitanOS
2283 Ultrix
2284 Unisys Dynix
ba58ab26
JH
2285
2286The following platforms have their own source code distributions and
500f1b69 2287binaries available via L<http://www.cpan.org/ports/>
ba58ab26 2288
cec2c193 2289 Perl release
ba58ab26 2290
522b859a 2291 OS/400 (ILE) 5.005_02
cec2c193 2292 Tandem Guardian 5.004
ba58ab26
JH
2293
2294The following platforms have only binaries available via
500f1b69 2295L<http://www.cpan.org/ports/index.html> :
ba58ab26 2296
cec2c193 2297 Perl release
ba58ab26 2298
cec2c193
JH
2299 Acorn RISCOS 5.005_02
2300 AOS 5.002
2301 LynxOS 5.004_02
ba58ab26
JH
2302
2303Although we do suggest that you always build your own Perl from
2304the source code, both for maximal configurability and for security,
2305in case you are in a hurry you can check
500f1b69 2306L<http://www.cpan.org/ports/index.html> for binary distributions.
ba58ab26 2307
c997b287
GS
2308=head1 SEE ALSO
2309
b6c36746 2310L<perlaix>, L<perlamiga>, L<perlbs2000>,
8d87852b 2311L<perlce>, L<perlcygwin>, L<perldos>,
469e7be4 2312L<perlebcdic>, L<perlfreebsd>, L<perlhurd>, L<perlhpux>, L<perlirix>,
b5afd346 2313L<perlmacos>, L<perlmacosx>,
522b859a
JH
2314L<perlnetware>, L<perlos2>, L<perlos390>, L<perlos400>,
2315L<perlplan9>, L<perlqnx>, L<perlsolaris>, L<perltru64>,
043fec90 2316L<perlunicode>, L<perlvms>, L<perlvos>, L<perlwin32>, and L<Win32>.
c997b287 2317
e41182b5
GS
2318=head1 AUTHORS / CONTRIBUTORS
2319
06e9666b 2320Abigail <abigail@foad.org>,
c47ff5f1
GS
2321Charles Bailey <bailey@newman.upenn.edu>,
2322Graham Barr <gbarr@pobox.com>,
2323Tom Christiansen <tchrist@perl.com>,
06e9666b 2324Nicholas Clark <nick@ccl4.org>,
c47ff5f1 2325Thomas Dorner <Thomas.Dorner@start.de>,
06e9666b
A
2326Andy Dougherty <doughera@lafayette.edu>,
2327Dominic Dunlop <domo@computer.org>,
2328Neale Ferguson <neale@vma.tabnsw.com.au>,
c47ff5f1 2329David J. Fiander <davidf@mks.com>,
3fd80bd6 2330Paul Green <Paul.Green@stratus.com>,
06e9666b 2331M.J.T. Guy <mjtg@cam.ac.uk>,
61f30a5e 2332Jarkko Hietaniemi <jhi@iki.fi>,
c47ff5f1 2333Luther Huffman <lutherh@stratcom.com>,
06e9666b
A
2334Nick Ing-Simmons <nick@ing-simmons.net>,
2335Andreas J. KE<ouml>nig <a.koenig@mind.de>,
c47ff5f1
GS
2336Markus Laker <mlaker@contax.co.uk>,
2337Andrew M. Langmead <aml@world.std.com>,
2338Larry Moore <ljmoore@freespace.net>,
2339Paul Moore <Paul.Moore@uk.origin-it.com>,
2340Chris Nandor <pudge@pobox.com>,
1afc07ec 2341Matthias Neeracher <neeracher@mac.com>,
e71a7dc8 2342Philip Newton <pne@cpan.org>,
c47ff5f1
GS
2343Gary Ng <71564.1743@CompuServe.COM>,
2344Tom Phoenix <rootbeer@teleport.com>,
2345AndrE<eacute> Pirard <A.Pirard@ulg.ac.be>,
2346Peter Prymmer <pvhp@forte.com>,
2347Hugo van der Sanden <hv@crypt0.demon.co.uk>,
2348Gurusamy Sarathy <gsar@activestate.com>,
2349Paul J. Schinder <schinder@pobox.com>,
2350Michael G Schwern <schwern@pobox.com>,
06e9666b 2351Dan Sugalski <dan@sidhe.org>,
bbe548ff 2352Nathan Torkington <gnat@frii.com>,
016930a6 2353John Malmberg <wb8tyw@qsl.net>