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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
7a4d2905 215As of perl 5.9.2, you can also use the C<E<gt>> and C<E<lt>> modifiers
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216to force big- or little-endian byte-order. This is useful if you want
217to store signed integers or 64-bit integers, for example.
218
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219You can explore the endianness of your platform by unpacking a
220data structure packed in native format such as:
221
222 print unpack("h*", pack("s2", 1, 2)), "\n";
223 # '10002000' on e.g. Intel x86 or Alpha 21064 in little-endian mode
224 # '00100020' on e.g. Motorola 68040
225
226If you need to distinguish between endian architectures you could use
227either of the variables set like so:
228
229 $is_big_endian = unpack("h*", pack("s", 1)) =~ /01/;
4375e838 230 $is_little_endian = unpack("h*", pack("s", 1)) =~ /^1/;
d1e3b762 231
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232Differing widths can cause truncation even between platforms of equal
233endianness. The platform of shorter width loses the upper parts of the
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234number. There is no good solution for this problem except to avoid
235transferring or storing raw binary numbers.
236
b7df3edc 237One can circumnavigate both these problems in two ways. Either
322422de 238transfer and store numbers always in text format, instead of raw
b7df3edc 239binary, or else consider using modules like Data::Dumper (included in
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240the standard distribution as of Perl 5.005) and Storable (included as
241of perl 5.8). Keeping all data as text significantly simplifies matters.
322422de 242
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243The v-strings are portable only up to v2147483647 (0x7FFFFFFF), that's
244how far EBCDIC, or more precisely UTF-EBCDIC will go.
245
433acd8a 246=head2 Files and Filesystems
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247
248Most platforms these days structure files in a hierarchical fashion.
b7df3edc 249So, it is reasonably safe to assume that all platforms support the
6ab3f9cb 250notion of a "path" to uniquely identify a file on the system. How
b7df3edc 251that path is really written, though, differs considerably.
e41182b5 252
4375e838 253Although similar, file path specifications differ between Unix,
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254Windows, S<Mac OS>, OS/2, VMS, VOS, S<RISC OS>, and probably others.
255Unix, for example, is one of the few OSes that has the elegant idea
256of a single root directory.
322422de 257
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258DOS, OS/2, VMS, VOS, and Windows can work similarly to Unix with C</>
259as path separator, or in their own idiosyncratic ways (such as having
260several root directories and various "unrooted" device files such NIL:
261and LPT:).
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,
68fb0eb7
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474if any. Third, the VMS port carefully sets up $^X and
475$Config{perlpath} so that no further processing is required. This is
476just as well, because the matching regular expression used below would
477then have to deal with a possible trailing version number in the VMS
478file name.
a10d74f3
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479
480To convert $^X to a file pathname, taking account of the requirements
481of the various operating system possibilities, say:
7ee27b7c 482
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
a61fc69c
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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
7137b697
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495=head2 Networking
496
497Don't assume that you can reach the public Internet.
498
499Don't assume that there is only one way to get through firewalls
500to the public Internet.
501
932f293e
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502Don't assume that you can reach outside world through any other port
503than 80, or some web proxy. ftp is blocked by many firewalls.
504
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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.
932f293e
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512
513Don't assume a particular network device name.
7137b697 514
dbc6a9ce 515Don't assume a particular set of ioctl()s will work.
7137b697
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516
517Don't assume that you can ping hosts and get replies.
518
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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
e41182b5
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531=head2 Interprocess Communication (IPC)
532
b7df3edc
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533In general, don't directly access the system in code meant to be
534portable. That means, no C<system>, C<exec>, C<fork>, C<pipe>,
535C<``>, C<qx//>, C<open> with a C<|>, nor any of the other things
536that makes being a perl hacker worth being.
e41182b5
GS
537
538Commands that launch external processes are generally supported on
b7df3edc
GS
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
b7df3edc
GS
550 open(MAIL, '|/usr/lib/sendmail -t')
551 or die "cannot fork sendmail: $!";
e41182b5
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552
553This is fine for systems programming when sendmail is known to be
554available. But it is not fine for many non-Unix systems, and even
555some Unix systems that may not have sendmail installed. If a portable
b7df3edc
GS
556solution is needed, see the various distributions on CPAN that deal
557with it. Mail::Mailer and Mail::Send in the MailTools distribution are
558commonly used, and provide several mailing methods, including mail,
559sendmail, and direct SMTP (via Net::SMTP) if a mail transfer agent is
560not available. Mail::Sendmail is a standalone module that provides
561simple, platform-independent mailing.
562
563The Unix System V IPC (C<msg*(), sem*(), shm*()>) is not available
564even on all Unix platforms.
e41182b5 565
a81e5e2e
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566Do not use either the bare result of C<pack("N", 10, 20, 30, 40)> or
567bare v-strings (such as C<v10.20.30.40>) to represent IPv4 addresses:
568both forms just pack the four bytes into network order. That this
569would be equal to the C language C<in_addr> struct (which is what the
570socket code internally uses) is not guaranteed. To be portable use
571the routines of the Socket extension, such as C<inet_aton()>,
572C<inet_ntoa()>, and C<sockaddr_in()>.
6b2463a0 573
e41182b5 574The rule of thumb for portable code is: Do it all in portable Perl, or
0a47030a
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575use a module (that may internally implement it with platform-specific
576code, but expose a common interface).
e41182b5 577
e41182b5
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578=head2 External Subroutines (XS)
579
b7df3edc 580XS code can usually be made to work with any platform, but dependent
e41182b5
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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
e41182b5
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592=head2 Standard Modules
593
594In general, the standard modules work across platforms. Notable
6ab3f9cb 595exceptions are the CPAN module (which currently makes connections to external
e41182b5 596programs that may not be available), platform-specific modules (like
6ab3f9cb 597ExtUtils::MM_VMS), and DBM modules.
e41182b5 598
b7df3edc 599There is no one DBM module available on all platforms.
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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
625defines YYYY-MM-DD as the date format, or YYYY-MM-DDTHH-MM-SS
626(that's a literal "T" separating the date from the time).
91d20606 627Please do use the ISO 8601 instead of making us guess what
c87488a3
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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
19799a22
GS
634When calculating specific times, such as for tests in time or date modules,
635it may be appropriate to calculate an offset for the epoch.
b7df3edc 636
19799a22 637 require Time::Local;
ceaffd1d 638 my $offset = Time::Local::timegm(0, 0, 0, 1, 0, 70);
b7df3edc 639
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640The value for C<$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".
322422de
GS
660
661=head2 Internationalisation
662
b7df3edc
GS
663If you may assume POSIX (a rather large assumption), you may read
664more about the POSIX locale system from L<perllocale>. The locale
665system at least attempts to make things a little bit more portable,
666or at least more convenient and native-friendly for non-English
667users. The system affects character sets and encoding, and date
668and time formatting--amongst other things.
e41182b5 669
c87488a3
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670If you really want to be international, you should consider Unicode.
671See L<perluniintro> and L<perlunicode> for more information.
672
11264fdb
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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
2575c402
JW
682of embedding the bytes as-is. (If you want to write your code in UTF-8,
683you can use the C<utf8>.) The C<bytes> and C<utf8> pragmata are
684available since Perl 5.6.0.
11264fdb 685
e41182b5
GS
686=head2 System Resources
687
0a47030a
GS
688If your code is destined for systems with severely constrained (or
689missing!) virtual memory systems then you want to be I<especially> mindful
690of avoiding wasteful constructs such as:
e41182b5
GS
691
692 # NOTE: this is no longer "bad" in perl5.005
693 for (0..10000000) {} # bad
694 for (my $x = 0; $x <= 10000000; ++$x) {} # good
695
ceaffd1d 696 my @lines = <$very_large_file>; # bad
e41182b5 697
ceaffd1d 698 while (<$fh>) {$file .= $_} # sometimes bad
699 my $file = join('', <$fh>); # better
e41182b5 700
b7df3edc
GS
701The last two constructs may appear unintuitive to most people. The
702first repeatedly grows a string, whereas the second allocates a
703large chunk of memory in one go. On some systems, the second is
704more efficient that the first.
0a47030a 705
e41182b5
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706=head2 Security
707
b7df3edc 708Most multi-user platforms provide basic levels of security, usually
ac036724 709implemented at the filesystem level. Some, however, unfortunately do
710not. Thus the notion of user id, or "home" directory,
b7df3edc
GS
711or even the state of being logged-in, may be unrecognizable on many
712platforms. If you write programs that are security-conscious, it
713is usually best to know what type of system you will be running
714under so that you can write code explicitly for that platform (or
715class of platforms).
0a47030a 716
e1020413 717Don't assume the Unix filesystem access semantics: the operating
a1667ba3
JH
718system or the filesystem may be using some ACL systems, which are
719richer languages than the usual rwx. Even if the rwx exist,
720their semantics might be different.
721
722(From security viewpoint testing for permissions before attempting to
723do something is silly anyway: if one tries this, there is potential
ac036724 724for race conditions. Someone or something might change the
a1667ba3
JH
725permissions between the permissions check and the actual operation.
726Just try the operation.)
727
e1020413 728Don't assume the Unix user and group semantics: especially, don't
2edcc0d9 729expect the C<< $< >> and C<< $> >> (or the C<$(> and C<$)>) to work
a1667ba3
JH
730for switching identities (or memberships).
731
732Don't assume set-uid and set-gid semantics. (And even if you do,
733think twice: set-uid and set-gid are a known can of security worms.)
734
e41182b5
GS
735=head2 Style
736
737For those times when it is necessary to have platform-specific code,
738consider keeping the platform-specific code in one place, making porting
6ab3f9cb 739to other platforms easier. Use the Config module and the special
0a47030a
GS
740variable C<$^O> to differentiate platforms, as described in
741L<"PLATFORMS">.
e41182b5 742
b7df3edc
GS
743Be careful in the tests you supply with your module or programs.
744Module code may be fully portable, but its tests might not be. This
745often happens when tests spawn off other processes or call external
746programs to aid in the testing, or when (as noted above) the tests
c87488a3
HS
747assume certain things about the filesystem and paths. Be careful not
748to depend on a specific output style for errors, such as when checking
749C<$!> after a failed system call. Using C<$!> for anything else than
750displaying it as output is doubtful (though see the Errno module for
751testing reasonably portably for error value). Some platforms expect
752a certain output format, and Perl on those platforms may have been
753adjusted accordingly. Most specifically, don't anchor a regex when
754testing an error value.
e41182b5 755
0a47030a 756=head1 CPAN Testers
e41182b5 757
0a47030a
GS
758Modules uploaded to CPAN are tested by a variety of volunteers on
759different platforms. These CPAN testers are notified by mail of each
e41182b5 760new upload, and reply to the list with PASS, FAIL, NA (not applicable to
0a47030a 761this platform), or UNKNOWN (unknown), along with any relevant notations.
e41182b5
GS
762
763The purpose of the testing is twofold: one, to help developers fix any
0a47030a 764problems in their code that crop up because of lack of testing on other
b7df3edc 765platforms; two, to provide users with information about whether
0a47030a 766a given module works on a given platform.
e41182b5 767
7ee27b7c
AT
768Also see:
769
e41182b5
GS
770=over 4
771
7ee27b7c
AT
772=item *
773
774Mailing list: cpan-testers@perl.org
775
776=item *
e41182b5 777
7ee27b7c 778Testing results: http://testers.cpan.org/
e41182b5
GS
779
780=back
781
e41182b5
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782=head1 PLATFORMS
783
784As of version 5.002, Perl is built with a C<$^O> variable that
785indicates the operating system it was built on. This was implemented
b7df3edc
GS
786to help speed up code that would otherwise have to C<use Config>
787and use the value of C<$Config{osname}>. Of course, to get more
e41182b5
GS
788detailed information about the system, looking into C<%Config> is
789certainly recommended.
790
b7df3edc
GS
791C<%Config> cannot always be trusted, however, because it was built
792at compile time. If perl was built in one place, then transferred
793elsewhere, some values may be wrong. The values may even have been
794edited after the fact.
6ab3f9cb 795
e41182b5
GS
796=head2 Unix
797
798Perl works on a bewildering variety of Unix and Unix-like platforms (see
799e.g. most of the files in the F<hints/> directory in the source code kit).
800On most of these systems, the value of C<$^O> (hence C<$Config{'osname'}>,
d1e3b762
GS
801too) is determined either by lowercasing and stripping punctuation from the
802first field of the string returned by typing C<uname -a> (or a similar command)
803at the shell prompt or by testing the file system for the presence of
804uniquely named files such as a kernel or header file. Here, for example,
805are a few of the more popular Unix flavors:
e41182b5 806
b7df3edc 807 uname $^O $Config{'archname'}
6ab3f9cb 808 --------------------------------------------
b7df3edc 809 AIX aix aix
6ab3f9cb 810 BSD/OS bsdos i386-bsdos
e1516da7 811 Darwin darwin darwin
6ab3f9cb
GS
812 dgux dgux AViiON-dgux
813 DYNIX/ptx dynixptx i386-dynixptx
b7df3edc 814 FreeBSD freebsd freebsd-i386
df00ff3b 815 Haiku haiku BePC-haiku
d1e3b762 816 Linux linux arm-linux
b7df3edc 817 Linux linux i386-linux
6ab3f9cb
GS
818 Linux linux i586-linux
819 Linux linux ppc-linux
b7df3edc
GS
820 HP-UX hpux PA-RISC1.1
821 IRIX irix irix
b787fad4 822 Mac OS X darwin darwin
d1e3b762
GS
823 NeXT 3 next next-fat
824 NeXT 4 next OPENSTEP-Mach
6ab3f9cb 825 openbsd openbsd i386-openbsd
b7df3edc 826 OSF1 dec_osf alpha-dec_osf
6ab3f9cb
GS
827 reliantunix-n svr4 RM400-svr4
828 SCO_SV sco_sv i386-sco_sv
829 SINIX-N svr4 RM400-svr4
830 sn4609 unicos CRAY_C90-unicos
831 sn6521 unicosmk t3e-unicosmk
832 sn9617 unicos CRAY_J90-unicos
b7df3edc
GS
833 SunOS solaris sun4-solaris
834 SunOS solaris i86pc-solaris
835 SunOS4 sunos sun4-sunos
e41182b5 836
b7df3edc
GS
837Because the value of C<$Config{archname}> may depend on the
838hardware architecture, it can vary more than the value of C<$^O>.
6ab3f9cb 839
e41182b5
GS
840=head2 DOS and Derivatives
841
b7df3edc 842Perl has long been ported to Intel-style microcomputers running under
e41182b5
GS
843systems like PC-DOS, MS-DOS, OS/2, and most Windows platforms you can
844bring yourself to mention (except for Windows CE, if you count that).
b7df3edc 845Users familiar with I<COMMAND.COM> or I<CMD.EXE> style shells should
e41182b5
GS
846be aware that each of these file specifications may have subtle
847differences:
848
ceaffd1d 849 my $filespec0 = "c:/foo/bar/file.txt";
850 my $filespec1 = "c:\\foo\\bar\\file.txt";
851 my $filespec2 = 'c:\foo\bar\file.txt';
852 my $filespec3 = 'c:\\foo\\bar\\file.txt';
e41182b5 853
b7df3edc
GS
854System calls accept either C</> or C<\> as the path separator.
855However, many command-line utilities of DOS vintage treat C</> as
856the option prefix, so may get confused by filenames containing C</>.
857Aside from calling any external programs, C</> will work just fine,
858and probably better, as it is more consistent with popular usage,
859and avoids the problem of remembering what to backwhack and what
860not to.
e41182b5 861
b7df3edc
GS
862The DOS FAT filesystem can accommodate only "8.3" style filenames. Under
863the "case-insensitive, but case-preserving" HPFS (OS/2) and NTFS (NT)
0a47030a 864filesystems you may have to be careful about case returned with functions
e41182b5
GS
865like C<readdir> or used with functions like C<open> or C<opendir>.
866
b7df3edc
GS
867DOS also treats several filenames as special, such as AUX, PRN,
868NUL, CON, COM1, LPT1, LPT2, etc. Unfortunately, sometimes these
869filenames won't even work if you include an explicit directory
870prefix. It is best to avoid such filenames, if you want your code
871to be portable to DOS and its derivatives. It's hard to know what
872these all are, unfortunately.
e41182b5
GS
873
874Users of these operating systems may also wish to make use of
b7df3edc 875scripts such as I<pl2bat.bat> or I<pl2cmd> to
e41182b5
GS
876put wrappers around your scripts.
877
878Newline (C<\n>) is translated as C<\015\012> by STDIO when reading from
6ab3f9cb
GS
879and writing to files (see L<"Newlines">). C<binmode(FILEHANDLE)>
880will keep C<\n> translated as C<\012> for that filehandle. Since it is a
881no-op on other systems, C<binmode> should be used for cross-platform code
b7df3edc
GS
882that deals with binary data. That's assuming you realize in advance
883that your data is in binary. General-purpose programs should
884often assume nothing about their data.
e41182b5 885
b7df3edc 886The C<$^O> variable and the C<$Config{archname}> values for various
e41182b5
GS
887DOSish perls are as follows:
888
67ac489e
MS
889 OS $^O $Config{archname} ID Version
890 --------------------------------------------------------
891 MS-DOS dos ?
892 PC-DOS dos ?
893 OS/2 os2 ?
894 Windows 3.1 ? ? 0 3 01
895 Windows 95 MSWin32 MSWin32-x86 1 4 00
896 Windows 98 MSWin32 MSWin32-x86 1 4 10
897 Windows ME MSWin32 MSWin32-x86 1 ?
898 Windows NT MSWin32 MSWin32-x86 2 4 xx
899 Windows NT MSWin32 MSWin32-ALPHA 2 4 xx
900 Windows NT MSWin32 MSWin32-ppc 2 4 xx
7ee27b7c
AT
901 Windows 2000 MSWin32 MSWin32-x86 2 5 00
902 Windows XP MSWin32 MSWin32-x86 2 5 01
903 Windows 2003 MSWin32 MSWin32-x86 2 5 02
bc643a33
CJ
904 Windows Vista MSWin32 MSWin32-x86 2 6 00
905 Windows 7 MSWin32 MSWin32-x86 2 6 01
906 Windows 7 MSWin32 MSWin32-x64 2 6 01
67ac489e 907 Windows CE MSWin32 ? 3
7ee27b7c 908 Cygwin cygwin cygwin
e41182b5 909
34aaaa84
PP
910The various MSWin32 Perl's can distinguish the OS they are running on
911via the value of the fifth element of the list returned from
912Win32::GetOSVersion(). For example:
913
914 if ($^O eq 'MSWin32') {
915 my @os_version_info = Win32::GetOSVersion();
916 print +('3.1','95','NT')[$os_version_info[4]],"\n";
917 }
918
7939d86b
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919There are also Win32::IsWinNT() and Win32::IsWin95(), try C<perldoc Win32>,
920and as of libwin32 0.19 (not part of the core Perl distribution)
921Win32::GetOSName(). The very portable POSIX::uname() will work too:
1d65be3a
JH
922
923 c:\> perl -MPOSIX -we "print join '|', uname"
924 Windows NT|moonru|5.0|Build 2195 (Service Pack 2)|x86
d99f392e 925
e41182b5
GS
926Also see:
927
928=over 4
929
c997b287 930=item *
e41182b5 931
c997b287
GS
932The djgpp environment for DOS, http://www.delorie.com/djgpp/
933and L<perldos>.
e41182b5 934
c997b287 935=item *
e41182b5 936
c997b287 937The EMX environment for DOS, OS/2, etc. emx@iaehv.nl,
f224927c 938ftp://hobbes.nmsu.edu/pub/os2/dev/emx/ Also L<perlos2>.
e41182b5 939
c997b287 940=item *
d1e3b762 941
c997b287
GS
942Build instructions for Win32 in L<perlwin32>, or under the Cygnus environment
943in L<perlcygwin>.
944
945=item *
946
947The C<Win32::*> modules in L<Win32>.
948
949=item *
950
951The ActiveState Pages, http://www.activestate.com/
952
953=item *
954
955The Cygwin environment for Win32; F<README.cygwin> (installed
47dafe4d 956as L<perlcygwin>), http://www.cygwin.com/
c997b287
GS
957
958=item *
959
960The U/WIN environment for Win32,
cea6626f 961http://www.research.att.com/sw/tools/uwin/
c997b287 962
cea6626f 963=item *
d1e3b762 964
cea6626f 965Build instructions for OS/2, L<perlos2>
d1e3b762 966
e41182b5
GS
967=back
968
e41182b5
GS
969=head2 VMS
970
c997b287 971Perl on VMS is discussed in L<perlvms> in the perl distribution.
016930a6
JM
972
973The official name of VMS as of this writing is OpenVMS.
974
b7df3edc 975Perl on VMS can accept either VMS- or Unix-style file
e41182b5
GS
976specifications as in either of the following:
977
978 $ perl -ne "print if /perl_setup/i" SYS$LOGIN:LOGIN.COM
979 $ perl -ne "print if /perl_setup/i" /sys$login/login.com
980
981but not a mixture of both as in:
982
983 $ perl -ne "print if /perl_setup/i" sys$login:/login.com
984 Can't open sys$login:/login.com: file specification syntax error
985
986Interacting with Perl from the Digital Command Language (DCL) shell
987often requires a different set of quotation marks than Unix shells do.
988For example:
989
990 $ perl -e "print ""Hello, world.\n"""
991 Hello, world.
992
b7df3edc 993There are several ways to wrap your perl scripts in DCL F<.COM> files, if
e41182b5
GS
994you are so inclined. For example:
995
996 $ write sys$output "Hello from DCL!"
997 $ if p1 .eqs. ""
998 $ then perl -x 'f$environment("PROCEDURE")
999 $ else perl -x - 'p1 'p2 'p3 'p4 'p5 'p6 'p7 'p8
1000 $ deck/dollars="__END__"
1001 #!/usr/bin/perl
1002
1003 print "Hello from Perl!\n";
1004
1005 __END__
1006 $ endif
1007
1008Do take care with C<$ ASSIGN/nolog/user SYS$COMMAND: SYS$INPUT> if your
c47ff5f1 1009perl-in-DCL script expects to do things like C<< $read = <STDIN>; >>.
e41182b5 1010
016930a6
JM
1011The VMS operating system has two filesystems, known as ODS-2 and ODS-5.
1012
1013For ODS-2, filenames are in the format "name.extension;version". The
1014maximum length for filenames is 39 characters, and the maximum length for
e41182b5
GS
1015extensions is also 39 characters. Version is a number from 1 to
101632767. Valid characters are C</[A-Z0-9$_-]/>.
1017
016930a6
JM
1018The ODS-2 filesystem is case-insensitive and does not preserve case.
1019Perl simulates this by converting all filenames to lowercase internally.
1020
1021For ODS-5, filenames may have almost any character in them and can include
1022Unicode characters. Characters that could be misinterpreted by the DCL
1023shell or file parsing utilities need to be prefixed with the C<^>
1024character, or replaced with hexadecimal characters prefixed with the
1025C<^> character. Such prefixing is only needed with the pathnames are
e1020413 1026in VMS format in applications. Programs that can accept the Unix format
016930a6
JM
1027of pathnames do not need the escape characters. The maximum length for
1028filenames is 255 characters. The ODS-5 file system can handle both
1029a case preserved and a case sensitive mode.
1030
1031ODS-5 is only available on the OpenVMS for 64 bit platforms.
1032
1033Support for the extended file specifications is being done as optional
1034settings to preserve backward compatibility with Perl scripts that
1035assume the previous VMS limitations.
1036
e1020413
TC
1037In general routines on VMS that get a Unix format file specification
1038should return it in a Unix format, and when they get a VMS format
016930a6
JM
1039specification they should return a VMS format unless they are documented
1040to do a conversion.
1041
1042For routines that generate return a file specification, VMS allows setting
1043if the C library which Perl is built on if it will be returned in VMS
e1020413 1044format or in Unix format.
016930a6
JM
1045
1046With the ODS-2 file system, there is not much difference in syntax of
e1020413 1047filenames without paths for VMS or Unix. With the extended character
016930a6
JM
1048set available with ODS-5 there can be a significant difference.
1049
1050Because of this, existing Perl scripts written for VMS were sometimes
e1020413 1051treating VMS and Unix filenames interchangeably. Without the extended
016930a6
JM
1052character set enabled, this behavior will mostly be maintained for
1053backwards compatibility.
1054
1055When extended characters are enabled with ODS-5, the handling of
e1020413 1056Unix formatted file specifications is to that of a Unix system.
016930a6
JM
1057
1058VMS file specifications without extensions have a trailing dot. An
e1020413 1059equivalent Unix file specification should not show the trailing dot.
016930a6
JM
1060
1061The result of all of this, is that for VMS, for portable scripts, you
1062can not depend on Perl to present the filenames in lowercase, to be
1063case sensitive, and that the filenames could be returned in either
e1020413 1064Unix or VMS format.
016930a6
JM
1065
1066And if a routine returns a file specification, unless it is intended to
1067convert it, it should return it in the same format as it found it.
1068
1069C<readdir> by default has traditionally returned lowercased filenames.
1070When the ODS-5 support is enabled, it will return the exact case of the
1071filename on the disk.
1072
1073Files without extensions have a trailing period on them, so doing a
1074C<readdir> in the default mode with a file named F<A.;5> will
1075return F<a.> when VMS is (though that file could be opened with
0a47030a 1076C<open(FH, 'A')>).
e41182b5 1077
016930a6 1078With support for extended file specifications and if C<opendir> was
e1020413 1079given a Unix format directory, a file named F<A.;5> will return F<a>
016930a6
JM
1080and optionally in the exact case on the disk. When C<opendir> is given
1081a VMS format directory, then C<readdir> should return F<a.>, and
1082again with the optionally the exact case.
1083
f34d0673 1084RMS had an eight level limit on directory depths from any rooted logical
1089a9e3
CB
1085(allowing 16 levels overall) prior to VMS 7.2, and even with versions of
1086VMS on VAX up through 7.3. Hence C<PERL_ROOT:[LIB.2.3.4.5.6.7.8]> is a
1087valid directory specification but C<PERL_ROOT:[LIB.2.3.4.5.6.7.8.9]> is
1088not. F<Makefile.PL> authors might have to take this into account, but at
1089least they can refer to the former as C</PERL_ROOT/lib/2/3/4/5/6/7/8/>.
1090
1091Pumpkings and module integrators can easily see whether files with too many
1092directory levels have snuck into the core by running the following in the
1093top-level source directory:
1094
a61fc69c 1095 $ perl -ne "$_=~s/\s+.*//; print if scalar(split /\//) > 8;" < MANIFEST
1089a9e3 1096
e41182b5 1097
6ab3f9cb 1098The VMS::Filespec module, which gets installed as part of the build
0a47030a
GS
1099process on VMS, is a pure Perl module that can easily be installed on
1100non-VMS platforms and can be helpful for conversions to and from RMS
016930a6
JM
1101native formats. It is also now the only way that you should check to
1102see if VMS is in a case sensitive mode.
e41182b5 1103
5e12dbfa
PP
1104What C<\n> represents depends on the type of file opened. It usually
1105represents C<\012> but it could also be C<\015>, C<\012>, C<\015\012>,
fa11829f 1106C<\000>, C<\040>, or nothing depending on the file organization and
5e12dbfa
PP
1107record format. The VMS::Stdio module provides access to the
1108special fopen() requirements of files with unusual attributes on VMS.
e41182b5
GS
1109
1110TCP/IP stacks are optional on VMS, so socket routines might not be
1111implemented. UDP sockets may not be supported.
1112
016930a6
JM
1113The TCP/IP library support for all current versions of VMS is dynamically
1114loaded if present, so even if the routines are configured, they may
1115return a status indicating that they are not implemented.
1116
e41182b5
GS
1117The value of C<$^O> on OpenVMS is "VMS". To determine the architecture
1118that you are running on without resorting to loading all of C<%Config>
1119you can examine the content of the C<@INC> array like so:
1120
1121 if (grep(/VMS_AXP/, @INC)) {
1122 print "I'm on Alpha!\n";
6ab3f9cb 1123
e41182b5
GS
1124 } elsif (grep(/VMS_VAX/, @INC)) {
1125 print "I'm on VAX!\n";
6ab3f9cb 1126
016930a6
JM
1127 } elsif (grep(/VMS_IA64/, @INC)) {
1128 print "I'm on IA64!\n";
1129
e41182b5
GS
1130 } else {
1131 print "I'm not so sure about where $^O is...\n";
1132 }
1133
016930a6
JM
1134In general, the significant differences should only be if Perl is running
1135on VMS_VAX or one of the 64 bit OpenVMS platforms.
1136
b7df3edc
GS
1137On VMS, perl determines the UTC offset from the C<SYS$TIMEZONE_DIFFERENTIAL>
1138logical name. Although the VMS epoch began at 17-NOV-1858 00:00:00.00,
6ab3f9cb 1139calls to C<localtime> are adjusted to count offsets from
b7df3edc 114001-JAN-1970 00:00:00.00, just like Unix.
6ab3f9cb 1141
e41182b5
GS
1142Also see:
1143
1144=over 4
1145
c997b287
GS
1146=item *
1147
1148F<README.vms> (installed as L<README_vms>), L<perlvms>
1149
1150=item *
1151
1089a9e3 1152vmsperl list, vmsperl-subscribe@perl.org
e41182b5 1153
c997b287 1154=item *
e41182b5 1155
c997b287 1156vmsperl on the web, http://www.sidhe.org/vmsperl/index.html
e41182b5
GS
1157
1158=back
1159
495c5fdc
GP
1160=head2 VOS
1161
9a997319
JH
1162Perl on VOS is discussed in F<README.vos> in the perl distribution
1163(installed as L<perlvos>). Perl on VOS can accept either VOS- or
1164Unix-style file specifications as in either of the following:
495c5fdc 1165
ea8b8ad2
VP
1166 $ perl -ne "print if /perl_setup/i" >system>notices
1167 $ perl -ne "print if /perl_setup/i" /system/notices
495c5fdc
GP
1168
1169or even a mixture of both as in:
1170
ea8b8ad2 1171 $ perl -ne "print if /perl_setup/i" >system/notices
495c5fdc 1172
b7df3edc 1173Even though VOS allows the slash character to appear in object
495c5fdc
GP
1174names, because the VOS port of Perl interprets it as a pathname
1175delimiting character, VOS files, directories, or links whose names
1176contain a slash character cannot be processed. Such files must be
a3dfe201 1177renamed before they can be processed by Perl. Note that VOS limits
b449fc5b
NC
1178file names to 32 or fewer characters, file names cannot start with a
1179C<-> character, or contain any character matching C<< tr/ !%&'()*+;<>?// >>
495c5fdc 1180
495c5fdc
GP
1181The value of C<$^O> on VOS is "VOS". To determine the architecture that
1182you are running on without resorting to loading all of C<%Config> you
c997b287 1183can examine the content of the @INC array like so:
495c5fdc 1184
24e8e380 1185 if ($^O =~ /VOS/) {
495c5fdc
GP
1186 print "I'm on a Stratus box!\n";
1187 } else {
1188 print "I'm not on a Stratus box!\n";
1189 die;
1190 }
1191
495c5fdc
GP
1192Also see:
1193
1194=over 4
1195
c997b287 1196=item *
495c5fdc 1197
cc07ed0b 1198F<README.vos> (installed as L<perlvos>)
c997b287
GS
1199
1200=item *
1201
1202The VOS mailing list.
495c5fdc
GP
1203
1204There is no specific mailing list for Perl on VOS. You can post
1205comments to the comp.sys.stratus newsgroup, or subscribe to the general
cc07ed0b 1206Stratus mailing list. Send a letter with "subscribe Info-Stratus" in
495c5fdc
GP
1207the message body to majordomo@list.stratagy.com.
1208
c997b287
GS
1209=item *
1210
cc07ed0b 1211VOS Perl on the web at http://ftp.stratus.com/pub/vos/posix/posix.html
495c5fdc
GP
1212
1213=back
1214
e41182b5
GS
1215=head2 EBCDIC Platforms
1216
1217Recent versions of Perl have been ported to platforms such as OS/400 on
d1e3b762
GS
1218AS/400 minicomputers as well as OS/390, VM/ESA, and BS2000 for S/390
1219Mainframes. Such computers use EBCDIC character sets internally (usually
0cc436d0
GS
1220Character Code Set ID 0037 for OS/400 and either 1047 or POSIX-BC for S/390
1221systems). On the mainframe perl currently works under the "Unix system
1222services for OS/390" (formerly known as OpenEdition), VM/ESA OpenEdition, or
1223the BS200 POSIX-BC system (BS2000 is supported in perl 5.6 and greater).
522b859a
JH
1224See L<perlos390> for details. Note that for OS/400 there is also a port of
1225Perl 5.8.1/5.9.0 or later to the PASE which is ASCII-based (as opposed to
1226ILE which is EBCDIC-based), see L<perlos400>.
e41182b5 1227
7c5ffed3
JH
1228As of R2.5 of USS for OS/390 and Version 2.3 of VM/ESA these Unix
1229sub-systems do not support the C<#!> shebang trick for script invocation.
1230Hence, on OS/390 and VM/ESA perl scripts can be executed with a header
1231similar to the following simple script:
e41182b5
GS
1232
1233 : # use perl
1234 eval 'exec /usr/local/bin/perl -S $0 ${1+"$@"}'
1235 if 0;
1236 #!/usr/local/bin/perl # just a comment really
1237
1238 print "Hello from perl!\n";
1239
d1e3b762
GS
1240OS/390 will support the C<#!> shebang trick in release 2.8 and beyond.
1241Calls to C<system> and backticks can use POSIX shell syntax on all
1242S/390 systems.
1243
b7df3edc 1244On the AS/400, if PERL5 is in your library list, you may need
6ab3f9cb
GS
1245to wrap your perl scripts in a CL procedure to invoke them like so:
1246
1247 BEGIN
1248 CALL PGM(PERL5/PERL) PARM('/QOpenSys/hello.pl')
1249 ENDPGM
1250
1251This will invoke the perl script F<hello.pl> in the root of the
1252QOpenSys file system. On the AS/400 calls to C<system> or backticks
1253must use CL syntax.
1254
e41182b5 1255On these platforms, bear in mind that the EBCDIC character set may have
0a47030a
GS
1256an effect on what happens with some perl functions (such as C<chr>,
1257C<pack>, C<print>, C<printf>, C<ord>, C<sort>, C<sprintf>, C<unpack>), as
1258well as bit-fiddling with ASCII constants using operators like C<^>, C<&>
1259and C<|>, not to mention dealing with socket interfaces to ASCII computers
6ab3f9cb 1260(see L<"Newlines">).
e41182b5 1261
b7df3edc
GS
1262Fortunately, most web servers for the mainframe will correctly
1263translate the C<\n> in the following statement to its ASCII equivalent
1264(C<\r> is the same under both Unix and OS/390 & VM/ESA):
e41182b5
GS
1265
1266 print "Content-type: text/html\r\n\r\n";
1267
d1e3b762 1268The values of C<$^O> on some of these platforms includes:
e41182b5 1269
d1e3b762
GS
1270 uname $^O $Config{'archname'}
1271 --------------------------------------------
1272 OS/390 os390 os390
1273 OS400 os400 os400
1274 POSIX-BC posix-bc BS2000-posix-bc
1275 VM/ESA vmesa vmesa
3c075c7d 1276
e41182b5
GS
1277Some simple tricks for determining if you are running on an EBCDIC
1278platform could include any of the following (perhaps all):
1279
ce7b6f06 1280 if ("\t" eq "\005") { print "EBCDIC may be spoken here!\n"; }
e41182b5
GS
1281
1282 if (ord('A') == 193) { print "EBCDIC may be spoken here!\n"; }
1283
1284 if (chr(169) eq 'z') { print "EBCDIC may be spoken here!\n"; }
1285
b7df3edc 1286One thing you may not want to rely on is the EBCDIC encoding
0a47030a
GS
1287of punctuation characters since these may differ from code page to code
1288page (and once your module or script is rumoured to work with EBCDIC,
1289folks will want it to work with all EBCDIC character sets).
e41182b5
GS
1290
1291Also see:
1292
1293=over 4
1294
c997b287
GS
1295=item *
1296
dc5c060f 1297L<perlos390>, F<README.os390>, F<perlbs2000>, F<README.vmesa>,
bb462878 1298L<perlebcdic>.
c997b287
GS
1299
1300=item *
e41182b5
GS
1301
1302The perl-mvs@perl.org list is for discussion of porting issues as well as
1303general usage issues for all EBCDIC Perls. Send a message body of
1304"subscribe perl-mvs" to majordomo@perl.org.
1305
7ee27b7c 1306=item *
c997b287
GS
1307
1308AS/400 Perl information at
b1866b2d 1309http://as400.rochester.ibm.com/
d1e3b762 1310as well as on CPAN in the F<ports/> directory.
e41182b5
GS
1311
1312=back
1313
b8099c3d
CN
1314=head2 Acorn RISC OS
1315
b7df3edc
GS
1316Because Acorns use ASCII with newlines (C<\n>) in text files as C<\012> like
1317Unix, and because Unix filename emulation is turned on by default,
1318most simple scripts will probably work "out of the box". The native
6ab3f9cb 1319filesystem is modular, and individual filesystems are free to be
0a47030a 1320case-sensitive or insensitive, and are usually case-preserving. Some
b7df3edc 1321native filesystems have name length limits, which file and directory
6ab3f9cb
GS
1322names are silently truncated to fit. Scripts should be aware that the
1323standard filesystem currently has a name length limit of B<10>
1324characters, with up to 77 items in a directory, but other filesystems
0a47030a 1325may not impose such limitations.
b8099c3d
CN
1326
1327Native filenames are of the form
1328
6ab3f9cb 1329 Filesystem#Special_Field::DiskName.$.Directory.Directory.File
dd9f0070 1330
b8099c3d
CN
1331where
1332
1333 Special_Field is not usually present, but may contain . and $ .
1334 Filesystem =~ m|[A-Za-z0-9_]|
1335 DsicName =~ m|[A-Za-z0-9_/]|
1336 $ represents the root directory
1337 . is the path separator
1338 @ is the current directory (per filesystem but machine global)
1339 ^ is the parent directory
1340 Directory and File =~ m|[^\0- "\.\$\%\&:\@\\^\|\177]+|
1341
1342The default filename translation is roughly C<tr|/.|./|;>
1343
6ab3f9cb 1344Note that C<"ADFS::HardDisk.$.File" ne 'ADFS::HardDisk.$.File'> and that
0a47030a
GS
1345the second stage of C<$> interpolation in regular expressions will fall
1346foul of the C<$.> if scripts are not careful.
1347
1348Logical paths specified by system variables containing comma-separated
b7df3edc 1349search lists are also allowed; hence C<System:Modules> is a valid
0a47030a 1350filename, and the filesystem will prefix C<Modules> with each section of
6ab3f9cb 1351C<System$Path> until a name is made that points to an object on disk.
b7df3edc 1352Writing to a new file C<System:Modules> would be allowed only if
0a47030a
GS
1353C<System$Path> contains a single item list. The filesystem will also
1354expand system variables in filenames if enclosed in angle brackets, so
c47ff5f1 1355C<< <System$Dir>.Modules >> would look for the file
0a47030a 1356S<C<$ENV{'System$Dir'} . 'Modules'>>. The obvious implication of this is
c47ff5f1 1357that B<fully qualified filenames can start with C<< <> >>> and should
0a47030a 1358be protected when C<open> is used for input.
b8099c3d
CN
1359
1360Because C<.> was in use as a directory separator and filenames could not
1361be assumed to be unique after 10 characters, Acorn implemented the C
1362compiler to strip the trailing C<.c> C<.h> C<.s> and C<.o> suffix from
1363filenames specified in source code and store the respective files in
b7df3edc 1364subdirectories named after the suffix. Hence files are translated:
b8099c3d
CN
1365
1366 foo.h h.foo
1367 C:foo.h C:h.foo (logical path variable)
1368 sys/os.h sys.h.os (C compiler groks Unix-speak)
1369 10charname.c c.10charname
1370 10charname.o o.10charname
1371 11charname_.c c.11charname (assuming filesystem truncates at 10)
1372
1373The Unix emulation library's translation of filenames to native assumes
b7df3edc
GS
1374that this sort of translation is required, and it allows a user-defined list
1375of known suffixes that it will transpose in this fashion. This may
1376seem transparent, but consider that with these rules C<foo/bar/baz.h>
0a47030a
GS
1377and C<foo/bar/h/baz> both map to C<foo.bar.h.baz>, and that C<readdir> and
1378C<glob> cannot and do not attempt to emulate the reverse mapping. Other
6ab3f9cb 1379C<.>'s in filenames are translated to C</>.
0a47030a 1380
b7df3edc 1381As implied above, the environment accessed through C<%ENV> is global, and
0a47030a 1382the convention is that program specific environment variables are of the
6ab3f9cb
GS
1383form C<Program$Name>. Each filesystem maintains a current directory,
1384and the current filesystem's current directory is the B<global> current
b7df3edc
GS
1385directory. Consequently, sociable programs don't change the current
1386directory but rely on full pathnames, and programs (and Makefiles) cannot
0a47030a
GS
1387assume that they can spawn a child process which can change the current
1388directory without affecting its parent (and everyone else for that
1389matter).
1390
b7df3edc
GS
1391Because native operating system filehandles are global and are currently
1392allocated down from 255, with 0 being a reserved value, the Unix emulation
0a47030a
GS
1393library emulates Unix filehandles. Consequently, you can't rely on
1394passing C<STDIN>, C<STDOUT>, or C<STDERR> to your children.
1395
1396The desire of users to express filenames of the form
c47ff5f1 1397C<< <Foo$Dir>.Bar >> on the command line unquoted causes problems,
0a47030a 1398too: C<``> command output capture has to perform a guessing game. It
c47ff5f1 1399assumes that a string C<< <[^<>]+\$[^<>]> >> is a
0a47030a 1400reference to an environment variable, whereas anything else involving
c47ff5f1 1401C<< < >> or C<< > >> is redirection, and generally manages to be 99%
0a47030a
GS
1402right. Of course, the problem remains that scripts cannot rely on any
1403Unix tools being available, or that any tools found have Unix-like command
1404line arguments.
1405
b7df3edc
GS
1406Extensions and XS are, in theory, buildable by anyone using free
1407tools. In practice, many don't, as users of the Acorn platform are
1408used to binary distributions. MakeMaker does run, but no available
1409make currently copes with MakeMaker's makefiles; even if and when
1410this should be fixed, the lack of a Unix-like shell will cause
1411problems with makefile rules, especially lines of the form C<cd
1412sdbm && make all>, and anything using quoting.
b8099c3d
CN
1413
1414"S<RISC OS>" is the proper name for the operating system, but the value
1415in C<$^O> is "riscos" (because we don't like shouting).
1416
e41182b5
GS
1417=head2 Other perls
1418
b7df3edc 1419Perl has been ported to many platforms that do not fit into any of
cd86ed9d
JV
1420the categories listed above. Some, such as AmigaOS, BeOS, HP MPE/iX,
1421QNX, Plan 9, and VOS, have been well-integrated into the standard
1422Perl source code kit. You may need to see the F<ports/> directory
1423on CPAN for information, and possibly binaries, for the likes of:
1424aos, Atari ST, lynxos, riscos, Novell Netware, Tandem Guardian,
1425I<etc.> (Yes, we know that some of these OSes may fall under the
1426Unix category, but we are not a standards body.)
e41182b5 1427
d1e3b762
GS
1428Some approximate operating system names and their C<$^O> values
1429in the "OTHER" category include:
1430
1431 OS $^O $Config{'archname'}
1432 ------------------------------------------
1433 Amiga DOS amigaos m68k-amigos
cec2c193 1434 BeOS beos
d1e3b762
GS
1435 MPE/iX mpeix PA-RISC1.1
1436
e41182b5
GS
1437See also:
1438
1439=over 4
1440
c997b287
GS
1441=item *
1442
1443Amiga, F<README.amiga> (installed as L<perlamiga>).
1444
1445=item *
d1e3b762 1446
c997b287 1447Be OS, F<README.beos>
e41182b5 1448
c997b287
GS
1449=item *
1450
1451HP 300 MPE/iX, F<README.mpeix> and Mark Bixby's web page
e59066d8 1452http://www.bixby.org/mark/porting.html
c997b287
GS
1453
1454=item *
e41182b5 1455
6ab3f9cb 1456A free perl5-based PERL.NLM for Novell Netware is available in
c997b287 1457precompiled binary and source code form from http://www.novell.com/
6ab3f9cb 1458as well as from CPAN.
e41182b5 1459
13a2d996 1460=item *
c997b287 1461
e6f03d26 1462S<Plan 9>, F<README.plan9>
d1e3b762 1463
e41182b5
GS
1464=back
1465
e41182b5
GS
1466=head1 FUNCTION IMPLEMENTATIONS
1467
b7df3edc
GS
1468Listed below are functions that are either completely unimplemented
1469or else have been implemented differently on various platforms.
1470Following each description will be, in parentheses, a list of
1471platforms that the description applies to.
e41182b5 1472
b7df3edc
GS
1473The list may well be incomplete, or even wrong in some places. When
1474in doubt, consult the platform-specific README files in the Perl
1475source distribution, and any other documentation resources accompanying
1476a given port.
e41182b5 1477
0a47030a 1478Be aware, moreover, that even among Unix-ish systems there are variations.
e41182b5 1479
b7df3edc
GS
1480For many functions, you can also query C<%Config>, exported by
1481default from the Config module. For example, to check whether the
1482platform has the C<lstat> call, check C<$Config{d_lstat}>. See
1483L<Config> for a full description of available variables.
e41182b5
GS
1484
1485=head2 Alphabetical Listing of Perl Functions
1486
1487=over 8
1488
e41182b5
GS
1489=item -X
1490
038ae9a4
SH
1491C<-w> only inspects the read-only file attribute (FILE_ATTRIBUTE_READONLY),
1492which determines whether the directory can be deleted, not whether it can
1493be written to. Directories always have read and write access unless denied
1494by discretionary access control lists (DACLs). (S<Win32>)
1495
b7df3edc
GS
1496C<-r>, C<-w>, C<-x>, and C<-o> tell whether the file is accessible,
1497which may not reflect UIC-based file protections. (VMS)
e41182b5 1498
b8099c3d
CN
1499C<-s> by name on an open file will return the space reserved on disk,
1500rather than the current extent. C<-s> on an open filehandle returns the
b7df3edc 1501current size. (S<RISC OS>)
b8099c3d 1502
e41182b5 1503C<-R>, C<-W>, C<-X>, C<-O> are indistinguishable from C<-r>, C<-w>,
204ad8d5 1504C<-x>, C<-o>. (Win32, VMS, S<RISC OS>)
e41182b5 1505
287a962e 1506C<-g>, C<-k>, C<-l>, C<-u>, C<-A> are not particularly meaningful.
b8099c3d 1507(Win32, VMS, S<RISC OS>)
e41182b5 1508
287a962e
JD
1509C<-p> is not particularly meaningful. (VMS, S<RISC OS>)
1510
e41182b5
GS
1511C<-d> is true if passed a device spec without an explicit directory.
1512(VMS)
1513
e41182b5 1514C<-x> (or C<-X>) determine if a file ends in one of the executable
b7df3edc 1515suffixes. C<-S> is meaningless. (Win32)
e41182b5 1516
b8099c3d
CN
1517C<-x> (or C<-X>) determine if a file has an executable file type.
1518(S<RISC OS>)
1519
aca72608
JD
1520=item alarm
1521
1522Emulated using timers that must be explicitly polled whenever Perl
1523wants to dispatch "safe signals" and therefore cannot interrupt
1524blocking system calls. (Win32)
1525
47cd99a4 1526=item atan2
519bc777
RGS
1527
1528Due to issues with various CPUs, math libraries, compilers, and standards,
1529results for C<atan2()> may vary depending on any combination of the above.
1530Perl attempts to conform to the Open Group/IEEE standards for the results
1531returned from C<atan2()>, but cannot force the issue if the system Perl is
1532run on does not allow it. (Tru64, HP-UX 10.20)
1533
1534The current version of the standards for C<atan2()> is available at
1535L<http://www.opengroup.org/onlinepubs/009695399/functions/atan2.html>.
1536
47cd99a4 1537=item binmode
e41182b5 1538
204ad8d5 1539Meaningless. (S<RISC OS>)
e41182b5
GS
1540
1541Reopens file and restores pointer; if function fails, underlying
1542filehandle may be closed, or pointer may be in a different position.
1543(VMS)
1544
1545The value returned by C<tell> may be affected after the call, and
1546the filehandle may be flushed. (Win32)
1547
47cd99a4 1548=item chmod
e41182b5 1549
e41182b5
GS
1550Only good for changing "owner" read-write access, "group", and "other"
1551bits are meaningless. (Win32)
1552
b8099c3d
CN
1553Only good for changing "owner" and "other" read-write access. (S<RISC OS>)
1554
495c5fdc
GP
1555Access permissions are mapped onto VOS access-control list changes. (VOS)
1556
4e51f8e4 1557The actual permissions set depend on the value of the C<CYGWIN>
789f0d36 1558in the SYSTEM environment settings. (Cygwin)
4e51f8e4 1559
47cd99a4 1560=item chown
e41182b5 1561
204ad8d5 1562Not implemented. (Win32, S<Plan 9>, S<RISC OS>)
e41182b5
GS
1563
1564Does nothing, but won't fail. (Win32)
1565
3fd80bd6
PG
1566A little funky, because VOS's notion of ownership is a little funky (VOS).
1567
e41182b5
GS
1568=item chroot
1569
204ad8d5 1570Not implemented. (Win32, VMS, S<Plan 9>, S<RISC OS>, VOS, VM/ESA)
e41182b5 1571
47cd99a4 1572=item crypt
e41182b5
GS
1573
1574May not be available if library or source was not provided when building
b8099c3d 1575perl. (Win32)
e41182b5 1576
47cd99a4 1577=item dbmclose
e41182b5 1578
e6f03d26 1579Not implemented. (VMS, S<Plan 9>, VOS)
e41182b5 1580
47cd99a4 1581=item dbmopen
e41182b5 1582
e6f03d26 1583Not implemented. (VMS, S<Plan 9>, VOS)
e41182b5 1584
47cd99a4 1585=item dump
e41182b5 1586
204ad8d5 1587Not useful. (S<RISC OS>)
e41182b5 1588
84d78eb7 1589Not supported. (Cygwin, Win32)
e41182b5 1590
b8099c3d 1591Invokes VMS debugger. (VMS)
e41182b5 1592
47cd99a4 1593=item exec
e41182b5 1594
7c5ffed3 1595Implemented via Spawn. (VM/ESA)
3c075c7d 1596
0f897271
GS
1597Does not automatically flush output handles on some platforms.
1598(SunOS, Solaris, HP-UX)
1599
fe12c0e8
MS
1600=item exit
1601
e1020413 1602Emulates Unix exit() (which considers C<exit 1> to indicate an error) by
fe12c0e8
MS
1603mapping the C<1> to SS$_ABORT (C<44>). This behavior may be overridden
1604with the pragma C<use vmsish 'exit'>. As with the CRTL's exit()
1605function, C<exit 0> is also mapped to an exit status of SS$_NORMAL
1606(C<1>); this mapping cannot be overridden. Any other argument to exit()
016930a6
JM
1607is used directly as Perl's exit status. On VMS, unless the future
1608POSIX_EXIT mode is enabled, the exit code should always be a valid
1609VMS exit code and not a generic number. When the POSIX_EXIT mode is
1610enabled, a generic number will be encoded in a method compatible with
1611the C library _POSIX_EXIT macro so that it can be decoded by other
1612programs, particularly ones written in C, like the GNV package. (VMS)
fe12c0e8 1613
47cd99a4 1614=item fcntl
e41182b5 1615
016930a6
JM
1616Not implemented. (Win32)
1617Some functions available based on the version of VMS. (VMS)
e41182b5 1618
47cd99a4 1619=item flock
e41182b5 1620
204ad8d5 1621Not implemented (VMS, S<RISC OS>, VOS).
e41182b5
GS
1622
1623Available only on Windows NT (not on Windows 95). (Win32)
1624
1625=item fork
1626
204ad8d5 1627Not implemented. (AmigaOS, S<RISC OS>, VM/ESA, VMS)
0f897271
GS
1628
1629Emulated using multiple interpreters. See L<perlfork>. (Win32)
1630
1631Does not automatically flush output handles on some platforms.
1632(SunOS, Solaris, HP-UX)
e41182b5
GS
1633
1634=item getlogin
1635
204ad8d5 1636Not implemented. (S<RISC OS>)
e41182b5 1637
47cd99a4 1638=item getpgrp
e41182b5 1639
204ad8d5 1640Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5
GS
1641
1642=item getppid
1643
204ad8d5 1644Not implemented. (Win32, S<RISC OS>)
e41182b5 1645
47cd99a4 1646=item getpriority
e41182b5 1647
204ad8d5 1648Not implemented. (Win32, VMS, S<RISC OS>, VOS, VM/ESA)
e41182b5 1649
47cd99a4 1650=item getpwnam
e41182b5 1651
204ad8d5 1652Not implemented. (Win32)
e41182b5 1653
b8099c3d
CN
1654Not useful. (S<RISC OS>)
1655
47cd99a4 1656=item getgrnam
e41182b5 1657
204ad8d5 1658Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5 1659
47cd99a4 1660=item getnetbyname
e41182b5 1661
204ad8d5 1662Not implemented. (Win32, S<Plan 9>)
e41182b5 1663
47cd99a4 1664=item getpwuid
e41182b5 1665
204ad8d5 1666Not implemented. (Win32)
e41182b5 1667
b8099c3d
CN
1668Not useful. (S<RISC OS>)
1669
47cd99a4 1670=item getgrgid
e41182b5 1671
204ad8d5 1672Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5 1673
47cd99a4 1674=item getnetbyaddr
e41182b5 1675
204ad8d5 1676Not implemented. (Win32, S<Plan 9>)
e41182b5 1677
47cd99a4 1678=item getprotobynumber
e41182b5 1679
47cd99a4 1680=item getservbyport
e41182b5 1681
e41182b5
GS
1682=item getpwent
1683
204ad8d5 1684Not implemented. (Win32, VM/ESA)
e41182b5
GS
1685
1686=item getgrent
1687
204ad8d5 1688Not implemented. (Win32, VMS, VM/ESA)
e41182b5 1689
ef5a6dd7
JH
1690=item gethostbyname
1691
1692C<gethostbyname('localhost')> does not work everywhere: you may have
204ad8d5 1693to use C<gethostbyname('127.0.0.1')>. (S<Irix 5>)
ef5a6dd7 1694
e41182b5
GS
1695=item gethostent
1696
204ad8d5 1697Not implemented. (Win32)
e41182b5
GS
1698
1699=item getnetent
1700
204ad8d5 1701Not implemented. (Win32, S<Plan 9>)
e41182b5
GS
1702
1703=item getprotoent
1704
204ad8d5 1705Not implemented. (Win32, S<Plan 9>)
e41182b5
GS
1706
1707=item getservent
1708
e6f03d26 1709Not implemented. (Win32, S<Plan 9>)
e41182b5 1710
47cd99a4 1711=item sethostent
e41182b5 1712
204ad8d5 1713Not implemented. (Win32, S<Plan 9>, S<RISC OS>)
e41182b5 1714
47cd99a4 1715=item setnetent
e41182b5 1716
204ad8d5 1717Not implemented. (Win32, S<Plan 9>, S<RISC OS>)
e41182b5 1718
47cd99a4 1719=item setprotoent
e41182b5 1720
204ad8d5 1721Not implemented. (Win32, S<Plan 9>, S<RISC OS>)
e41182b5 1722
47cd99a4 1723=item setservent
e41182b5 1724
e6f03d26 1725Not implemented. (S<Plan 9>, Win32, S<RISC OS>)
e41182b5
GS
1726
1727=item endpwent
1728
204ad8d5 1729Not implemented. (MPE/iX, VM/ESA, Win32)
e41182b5
GS
1730
1731=item endgrent
1732
204ad8d5 1733Not implemented. (MPE/iX, S<RISC OS>, VM/ESA, VMS, Win32)
e41182b5
GS
1734
1735=item endhostent
1736
204ad8d5 1737Not implemented. (Win32)
e41182b5
GS
1738
1739=item endnetent
1740
204ad8d5 1741Not implemented. (Win32, S<Plan 9>)
e41182b5
GS
1742
1743=item endprotoent
1744
204ad8d5 1745Not implemented. (Win32, S<Plan 9>)
e41182b5
GS
1746
1747=item endservent
1748
e6f03d26 1749Not implemented. (S<Plan 9>, Win32)
e41182b5
GS
1750
1751=item getsockopt SOCKET,LEVEL,OPTNAME
1752
e6f03d26 1753Not implemented. (S<Plan 9>)
e41182b5 1754
e41182b5
GS
1755=item glob
1756
63f87e49
GS
1757This operator is implemented via the File::Glob extension on most
1758platforms. See L<File::Glob> for portability information.
b8099c3d 1759
62aa5637
MS
1760=item gmtime
1761
461d5a49
MS
1762In theory, gmtime() is reliable from -2**63 to 2**63-1. However,
1763because work arounds in the implementation use floating point numbers,
1764it will become inaccurate as the time gets larger. This is a bug and
1765will be fixed in the future.
62aa5637 1766
e41182b5
GS
1767=item ioctl FILEHANDLE,FUNCTION,SCALAR
1768
1769Not implemented. (VMS)
1770
1771Available only for socket handles, and it does what the ioctlsocket() call
1772in the Winsock API does. (Win32)
1773
b8099c3d
CN
1774Available only for socket handles. (S<RISC OS>)
1775
47cd99a4 1776=item kill
e41182b5 1777
862b5365 1778Not implemented, hence not useful for taint checking. (S<RISC OS>)
e41182b5 1779
63f87e49
GS
1780C<kill()> doesn't have the semantics of C<raise()>, i.e. it doesn't send
1781a signal to the identified process like it does on Unix platforms.
1782Instead C<kill($sig, $pid)> terminates the process identified by $pid,
1783and makes it exit immediately with exit status $sig. As in Unix, if
1784$sig is 0 and the specified process exists, it returns true without
1785actually terminating it. (Win32)
e41182b5 1786
d0302514
JD
1787C<kill(-9, $pid)> will terminate the process specified by $pid and
1788recursively all child processes owned by it. This is different from
1789the Unix semantics, where the signal will be delivered to all
1790processes in the same process group as the process specified by
1791$pid. (Win32)
1792
016930a6
JM
1793Is not supported for process identification number of 0 or negative
1794numbers. (VMS)
1795
47cd99a4 1796=item link
e41182b5 1797
204ad8d5 1798Not implemented. (MPE/iX, S<RISC OS>)
e41182b5 1799
433acd8a
JH
1800Link count not updated because hard links are not quite that hard
1801(They are sort of half-way between hard and soft links). (AmigaOS)
1802
63d6c08b
JD
1803Hard links are implemented on Win32 under NTFS only. They are
1804natively supported on Windows 2000 and later. On Windows NT they
1805are implemented using the Windows POSIX subsystem support and the
1806Perl process will need Administrator or Backup Operator privileges
1807to create hard links.
a3dfe201 1808
016930a6
JM
1809Available on 64 bit OpenVMS 8.2 and later. (VMS)
1810
62aa5637
MS
1811=item localtime
1812
a61fc69c 1813localtime() has the same range as L</gmtime>, but because time zone
dc164757
MS
1814rules change its accuracy for historical and future times may degrade
1815but usually by no more than an hour.
62aa5637 1816
e41182b5
GS
1817=item lstat
1818
016930a6 1819Not implemented. (S<RISC OS>)
e41182b5 1820
63f87e49 1821Return values (especially for device and inode) may be bogus. (Win32)
e41182b5 1822
47cd99a4 1823=item msgctl
e41182b5 1824
47cd99a4 1825=item msgget
e41182b5 1826
47cd99a4 1827=item msgsnd
e41182b5 1828
47cd99a4 1829=item msgrcv
e41182b5 1830
204ad8d5 1831Not implemented. (Win32, VMS, S<Plan 9>, S<RISC OS>, VOS)
e41182b5 1832
47cd99a4 1833=item open
e41182b5 1834
204ad8d5 1835open to C<|-> and C<-|> are unsupported. (Win32, S<RISC OS>)
e41182b5 1836
0f897271
GS
1837Opening a process does not automatically flush output handles on some
1838platforms. (SunOS, Solaris, HP-UX)
1839
e41182b5
GS
1840=item readlink
1841
b8099c3d 1842Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5 1843
47cd99a4 1844=item rename
c9b2b9d4
SS
1845
1846Can't move directories between directories on different logical volumes. (Win32)
1847
47cd99a4 1848=item select
e41182b5 1849
689c5c24 1850Only implemented on sockets. (Win32, VMS)
e41182b5 1851
b8099c3d
CN
1852Only reliable on sockets. (S<RISC OS>)
1853
76e05f0b 1854Note that the C<select FILEHANDLE> form is generally portable.
63f87e49 1855
47cd99a4 1856=item semctl
e41182b5 1857
47cd99a4 1858=item semget
e41182b5 1859
47cd99a4 1860=item semop
e41182b5 1861
204ad8d5 1862Not implemented. ( Win32, VMS, S<RISC OS>, VOS)
e41182b5 1863
a3dfe201
GS
1864=item setgrent
1865
204ad8d5 1866Not implemented. (MPE/iX, VMS, Win32, S<RISC OS>, VOS)
a3dfe201 1867
47cd99a4 1868=item setpgrp
e41182b5 1869
204ad8d5 1870Not implemented. (Win32, VMS, S<RISC OS>, VOS)
e41182b5 1871
47cd99a4 1872=item setpriority
e41182b5 1873
204ad8d5 1874Not implemented. (Win32, VMS, S<RISC OS>, VOS)
e41182b5 1875
a3dfe201
GS
1876=item setpwent
1877
204ad8d5 1878Not implemented. (MPE/iX, Win32, S<RISC OS>, VOS)
a3dfe201 1879
47cd99a4 1880=item setsockopt
e41182b5 1881
e6f03d26 1882Not implemented. (S<Plan 9>)
e41182b5 1883
47cd99a4 1884=item shmctl
e41182b5 1885
47cd99a4 1886=item shmget
e41182b5 1887
47cd99a4 1888=item shmread
e41182b5 1889
47cd99a4 1890=item shmwrite
e41182b5 1891
204ad8d5 1892Not implemented. (Win32, VMS, S<RISC OS>, VOS)
e41182b5 1893
47cd99a4 1894=item sockatmark
80cbd5ad
JH
1895
1896A relatively recent addition to socket functions, may not
e1020413 1897be implemented even in Unix platforms.
80cbd5ad 1898
47cd99a4 1899=item socketpair
e41182b5 1900
f38e12df 1901Not implemented. (S<RISC OS>, VOS, VM/ESA)
016930a6
JM
1902
1903Available on 64 bit OpenVMS 8.2 and later. (VMS)
e41182b5 1904
e41182b5
GS
1905=item stat
1906
d62e1b7f
JH
1907Platforms that do not have rdev, blksize, or blocks will return these
1908as '', so numeric comparison or manipulation of these fields may cause
1909'not numeric' warnings.
1910
3f1f789b 1911ctime not supported on UFS (S<Mac OS X>).
e41182b5 1912
95a3fe12
MS
1913ctime is creation time instead of inode change time (Win32).
1914
e41182b5
GS
1915device and inode are not meaningful. (Win32)
1916
1917device and inode are not necessarily reliable. (VMS)
1918
b8099c3d
CN
1919mtime, atime and ctime all return the last modification time. Device and
1920inode are not necessarily reliable. (S<RISC OS>)
1921
d62e1b7f
JH
1922dev, rdev, blksize, and blocks are not available. inode is not
1923meaningful and will differ between stat calls on the same file. (os2)
1924
73e9292c
JH
1925some versions of cygwin when doing a stat("foo") and if not finding it
1926may then attempt to stat("foo.exe") (Cygwin)
1927
1fafdf34
JD
1928On Win32 stat() needs to open the file to determine the link count
1929and update attributes that may have been changed through hard links.
1930Setting ${^WIN32_SLOPPY_STAT} to a true value speeds up stat() by
1931not performing this operation. (Win32)
1932
47cd99a4 1933=item symlink
e41182b5 1934
c73b03b7
JM
1935Not implemented. (Win32, S<RISC OS>)
1936
1937Implemented on 64 bit VMS 8.3. VMS requires the symbolic link to be in Unix
1938syntax if it is intended to resolve to a valid path.
e41182b5 1939
47cd99a4 1940=item syscall
e41182b5 1941
204ad8d5 1942Not implemented. (Win32, VMS, S<RISC OS>, VOS, VM/ESA)
e41182b5 1943
47cd99a4 1944=item sysopen
f34d0673 1945
dd9f0070 1946The traditional "0", "1", and "2" MODEs are implemented with different
322422de
GS
1947numeric values on some systems. The flags exported by C<Fcntl>
1948(O_RDONLY, O_WRONLY, O_RDWR) should work everywhere though. (S<Mac
7c5ffed3 1949OS>, OS/390, VM/ESA)
f34d0673 1950
47cd99a4 1951=item system
e41182b5 1952
e41182b5 1953As an optimization, may not call the command shell specified in
b7df3edc 1954C<$ENV{PERL5SHELL}>. C<system(1, @args)> spawns an external
e41182b5
GS
1955process and immediately returns its process designator, without
1956waiting for it to terminate. Return value may be used subsequently
63f87e49
GS
1957in C<wait> or C<waitpid>. Failure to spawn() a subprocess is indicated
1958by setting $? to "255 << 8". C<$?> is set in a way compatible with
1959Unix (i.e. the exitstatus of the subprocess is obtained by "$? >> 8",
1960as described in the documentation). (Win32)
e41182b5 1961
b8099c3d
CN
1962There is no shell to process metacharacters, and the native standard is
1963to pass a command line terminated by "\n" "\r" or "\0" to the spawned
c47ff5f1 1964program. Redirection such as C<< > foo >> is performed (if at all) by
b8099c3d
CN
1965the run time library of the spawned program. C<system> I<list> will call
1966the Unix emulation library's C<exec> emulation, which attempts to provide
1967emulation of the stdin, stdout, stderr in force in the parent, providing
1968the child program uses a compatible version of the emulation library.
1969I<scalar> will call the native command line direct and no such emulation
1970of a child Unix program will exists. Mileage B<will> vary. (S<RISC OS>)
1971
0f897271
GS
1972Does not automatically flush output handles on some platforms.
1973(SunOS, Solaris, HP-UX)
1974
9bc98430
CB
1975The return value is POSIX-like (shifted up by 8 bits), which only allows
1976room for a made-up value derived from the severity bits of the native
197732-bit condition code (unless overridden by C<use vmsish 'status'>).
016930a6
JM
1978If the native condition code is one that has a POSIX value encoded, the
1979POSIX value will be decoded to extract the expected exit value.
9bc98430
CB
1980For more details see L<perlvms/$?>. (VMS)
1981
e41182b5
GS
1982=item times
1983
63f87e49
GS
1984"cumulative" times will be bogus. On anything other than Windows NT
1985or Windows 2000, "system" time will be bogus, and "user" time is
1986actually the time returned by the clock() function in the C runtime
1987library. (Win32)
e41182b5 1988
b8099c3d
CN
1989Not useful. (S<RISC OS>)
1990
47cd99a4 1991=item truncate
e41182b5 1992
6d738113 1993Not implemented. (Older versions of VMS)
e41182b5 1994
3fd80bd6 1995Truncation to same-or-shorter lengths only. (VOS)
495c5fdc 1996
4cfdb94f 1997If a FILEHANDLE is supplied, it must be writable and opened in append
e71a7dc8 1998mode (i.e., use C<<< open(FH, '>>filename') >>>
4cfdb94f
GS
1999or C<sysopen(FH,...,O_APPEND|O_RDWR)>. If a filename is supplied, it
2000should not be held open elsewhere. (Win32)
2001
e41182b5
GS
2002=item umask
2003
2004Returns undef where unavailable, as of version 5.005.
2005
b7df3edc
GS
2006C<umask> works but the correct permissions are set only when the file
2007is finally closed. (AmigaOS)
433acd8a 2008
47cd99a4 2009=item utime
e41182b5 2010
204ad8d5 2011Only the modification time is updated. (S<BeOS>, VMS, S<RISC OS>)
e41182b5 2012
322422de
GS
2013May not behave as expected. Behavior depends on the C runtime
2014library's implementation of utime(), and the filesystem being
2015used. The FAT filesystem typically does not support an "access
2016time" field, and it may limit timestamps to a granularity of
2017two seconds. (Win32)
e41182b5
GS
2018
2019=item wait
2020
47cd99a4 2021=item waitpid
e41182b5 2022
e41182b5 2023Can only be applied to process handles returned for processes spawned
a6f858fb 2024using C<system(1, ...)> or pseudo processes created with C<fork()>. (Win32)
e41182b5 2025
b8099c3d
CN
2026Not useful. (S<RISC OS>)
2027
e41182b5
GS
2028=back
2029
2030
7c35b6af 2031=head1 Supported Platforms
ba58ab26 2032
7c35b6af
RGS
2033The following platforms are known to build Perl 5.12 (as of April 2010,
2034its release date) from the standard source code distribution available
bb377ba2
JV
2035at http://www.cpan.org/src
2036
bb377ba2
JV
2037=over
2038
2039=item Linux (x86, ARM, IA64)
2040
e0d9a2c8 2041=item HP-UX
bb377ba2
JV
2042
2043=item AIX
2044
2045=item Win32
2046
2047=over
2048
2049=item Windows 2000
2050
2051=item Windows XP
2052
2053=item Windows Server 2003
2054
2055=item Windows Vista
2056
2057=item Windows Server 2008
2058
3b665c47
JD
2059=item Windows 7
2060
bb377ba2
JV
2061=back
2062
2d9ede6e
JH
2063=item Cygwin
2064
bb377ba2
JV
2065=item Solaris (x86, SPARC)
2066
1b0ab010
JV
2067=item OpenVMS
2068
2069=over
2070
2071=item Alpha (7.2 and later)
2072
2073=item I64 (8.2 and later)
2074
2075=back
bb377ba2
JV
2076
2077=item Symbian
2078
2079=item NetBSD
2080
2081=item FreeBSD
2082
2083=item Haiku
2084
2085=item Irix (6.5. What else?)
2086
2087=item OpenBSD
2088
2089=item Dragonfly BSD
2090
2091=item MirOS BSD
2092
2093Caveats:
2094
2095=over
2096
2097=item time_t issues that may or may not be fixed
2098
2099=back
2100
2101
2102=item Symbian (Series 60 v3, 3.2 and 5 - what else?)
2103
2104=item Stratus VOS
2105
2106=item AIX
2107
2108=back
2109
2110=head1 EOL Platforms (Perl 5.12)
2111
2112The following platforms were supported by a previous version of
2113Perl but have been officially removed from Perl's source code
2114as of 5.12:
2115
2116=over
2117
2118=item Atari MiNT
2119
2120=item Apollo Domain/OS
2121
2122=item Apple Mac OS 8/9
2123
2124=item Tenon Machten
2125
2126=back
2127
2128The following platforms may still work as of Perl 5.12, but Perl's
2129developers have made an explicit decision to discontinue support for
2130them:
2131
2132=over
2133
2134=item Windows 95
2135
2136=item Windows 98
2137
2138=item Windows ME
2139
2140=item Windows NT4
2141
2142=back
2143
2144=head1 Supported Platforms (Perl 5.8)
2145
2146As of July 2002 (the Perl release 5.8.0), the following platforms were
cec2c193 2147able to build Perl from the standard source code distribution
e59066d8 2148available at http://www.cpan.org/src/
cec2c193
JH
2149
2150 AIX
2151 BeOS
6f683aa2 2152 BSD/OS (BSDi)
cec2c193
JH
2153 Cygwin
2154 DG/UX
811b48f2 2155 DOS DJGPP 1)
cec2c193
JH
2156 DYNIX/ptx
2157 EPOC R5
2158 FreeBSD
6f683aa2 2159 HI-UXMPP (Hitachi) (5.8.0 worked but we didn't know it)
cec2c193
JH
2160 HP-UX
2161 IRIX
2162 Linux
8939ba94 2163 Mac OS Classic
6f683aa2 2164 Mac OS X (Darwin)
cec2c193
JH
2165 MPE/iX
2166 NetBSD
2167 NetWare
2168 NonStop-UX
6f683aa2 2169 ReliantUNIX (formerly SINIX)
cec2c193 2170 OpenBSD
6f683aa2 2171 OpenVMS (formerly VMS)
3ebac25b 2172 Open UNIX (Unixware) (since Perl 5.8.1/5.9.0)
cec2c193 2173 OS/2
522b859a 2174 OS/400 (using the PASE) (since Perl 5.8.1/5.9.0)
70de81db 2175 PowerUX
6f683aa2 2176 POSIX-BC (formerly BS2000)
cec2c193
JH
2177 QNX
2178 Solaris
70de81db 2179 SunOS 4
6f683aa2
JH
2180 SUPER-UX (NEC)
2181 Tru64 UNIX (formerly DEC OSF/1, Digital UNIX)
cec2c193
JH
2182 UNICOS
2183 UNICOS/mk
2184 UTS
2185 VOS
811b48f2 2186 Win95/98/ME/2K/XP 2)
c40b5d1d 2187 WinCE
6f683aa2 2188 z/OS (formerly OS/390)
cec2c193 2189 VM/ESA
ba58ab26 2190
811b48f2
JH
2191 1) in DOS mode either the DOS or OS/2 ports can be used
2192 2) compilers: Borland, MinGW (GCC), VC6
cec2c193 2193
c40b5d1d 2194The following platforms worked with the previous releases (5.6 and
cec2c193
JH
21955.7), but we did not manage either to fix or to test these in time
2196for the 5.8.0 release. There is a very good chance that many of these
70de81db 2197will work fine with the 5.8.0.
cec2c193 2198
8da2b1be 2199 BSD/OS
cec2c193
JH
2200 DomainOS
2201 Hurd
2202 LynxOS
2203 MachTen
2204 PowerMAX
2205 SCO SV
cec2c193
JH
2206 SVR4
2207 Unixware
2208 Windows 3.1
ba58ab26 2209
70de81db
JH
2210Known to be broken for 5.8.0 (but 5.6.1 and 5.7.2 can be used):
2211
2212 AmigaOS
2213
ba58ab26 2214The following platforms have been known to build Perl from source in
fd46a41b
JH
2215the past (5.005_03 and earlier), but we haven't been able to verify
2216their status for the current release, either because the
2217hardware/software platforms are rare or because we don't have an
2218active champion on these platforms--or both. They used to work,
2219though, so go ahead and try compiling them, and let perlbug@perl.org
2220of any trouble.
ba58ab26 2221
cec2c193
JH
2222 3b1
2223 A/UX
cec2c193
JH
2224 ConvexOS
2225 CX/UX
2226 DC/OSx
2227 DDE SMES
2228 DOS EMX
2229 Dynix
2230 EP/IX
2231 ESIX
2232 FPS
2233 GENIX
2234 Greenhills
2235 ISC
2236 MachTen 68k
cec2c193
JH
2237 MPC
2238 NEWS-OS
2239 NextSTEP
2240 OpenSTEP
2241 Opus
2242 Plan 9
cec2c193 2243 RISC/os
8da2b1be 2244 SCO ODT/OSR
cec2c193
JH
2245 Stellar
2246 SVR2
2247 TI1500
2248 TitanOS
2249 Ultrix
2250 Unisys Dynix
ba58ab26
JH
2251
2252The following platforms have their own source code distributions and
1577cd80 2253binaries available via http://www.cpan.org/ports/
ba58ab26 2254
cec2c193 2255 Perl release
ba58ab26 2256
522b859a 2257 OS/400 (ILE) 5.005_02
cec2c193 2258 Tandem Guardian 5.004
ba58ab26
JH
2259
2260The following platforms have only binaries available via
a93751fa 2261http://www.cpan.org/ports/index.html :
ba58ab26 2262
cec2c193 2263 Perl release
ba58ab26 2264
cec2c193
JH
2265 Acorn RISCOS 5.005_02
2266 AOS 5.002
2267 LynxOS 5.004_02
ba58ab26
JH
2268
2269Although we do suggest that you always build your own Perl from
2270the source code, both for maximal configurability and for security,
2271in case you are in a hurry you can check
a93751fa 2272http://www.cpan.org/ports/index.html for binary distributions.
ba58ab26 2273
c997b287
GS
2274=head1 SEE ALSO
2275
cec2c193 2276L<perlaix>, L<perlamiga>, L<perlapollo>, L<perlbeos>, L<perlbs2000>,
18a271bd 2277L<perlce>, L<perlcygwin>, L<perldgux>, L<perldos>, L<perlepoc>,
469e7be4 2278L<perlebcdic>, L<perlfreebsd>, L<perlhurd>, L<perlhpux>, L<perlirix>,
e94c1c05 2279L<perlmacos>, L<perlmacosx>, L<perlmpeix>,
522b859a
JH
2280L<perlnetware>, L<perlos2>, L<perlos390>, L<perlos400>,
2281L<perlplan9>, L<perlqnx>, L<perlsolaris>, L<perltru64>,
2282L<perlunicode>, L<perlvmesa>, L<perlvms>, L<perlvos>,
2283L<perlwin32>, and L<Win32>.
c997b287 2284
e41182b5
GS
2285=head1 AUTHORS / CONTRIBUTORS
2286
06e9666b 2287Abigail <abigail@foad.org>,
c47ff5f1
GS
2288Charles Bailey <bailey@newman.upenn.edu>,
2289Graham Barr <gbarr@pobox.com>,
2290Tom Christiansen <tchrist@perl.com>,
06e9666b 2291Nicholas Clark <nick@ccl4.org>,
c47ff5f1 2292Thomas Dorner <Thomas.Dorner@start.de>,
06e9666b
A
2293Andy Dougherty <doughera@lafayette.edu>,
2294Dominic Dunlop <domo@computer.org>,
2295Neale Ferguson <neale@vma.tabnsw.com.au>,
c47ff5f1 2296David J. Fiander <davidf@mks.com>,
3fd80bd6 2297Paul Green <Paul.Green@stratus.com>,
06e9666b 2298M.J.T. Guy <mjtg@cam.ac.uk>,
61f30a5e 2299Jarkko Hietaniemi <jhi@iki.fi>,
c47ff5f1 2300Luther Huffman <lutherh@stratcom.com>,
06e9666b
A
2301Nick Ing-Simmons <nick@ing-simmons.net>,
2302Andreas J. KE<ouml>nig <a.koenig@mind.de>,
c47ff5f1
GS
2303Markus Laker <mlaker@contax.co.uk>,
2304Andrew M. Langmead <aml@world.std.com>,
2305Larry Moore <ljmoore@freespace.net>,
2306Paul Moore <Paul.Moore@uk.origin-it.com>,
2307Chris Nandor <pudge@pobox.com>,
1afc07ec 2308Matthias Neeracher <neeracher@mac.com>,
e71a7dc8 2309Philip Newton <pne@cpan.org>,
c47ff5f1
GS
2310Gary Ng <71564.1743@CompuServe.COM>,
2311Tom Phoenix <rootbeer@teleport.com>,
2312AndrE<eacute> Pirard <A.Pirard@ulg.ac.be>,
2313Peter Prymmer <pvhp@forte.com>,
2314Hugo van der Sanden <hv@crypt0.demon.co.uk>,
2315Gurusamy Sarathy <gsar@activestate.com>,
2316Paul J. Schinder <schinder@pobox.com>,
2317Michael G Schwern <schwern@pobox.com>,
06e9666b 2318Dan Sugalski <dan@sidhe.org>,
c47ff5f1 2319Nathan Torkington <gnat@frii.com>.
016930a6 2320John Malmberg <wb8tyw@qsl.net>