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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
dbc6a9ce
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505Don't assume that you can send email by connecting to the local SMTP port.
506
7137b697 507Don't assume that you can reach yourself or any node by the name
dbc6a9ce 508'localhost'. The same goes for '127.0.0.1'. You will have to try both.
932f293e 509
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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
HS
623because that is OS- and implementation-specific. It is better to
624store a date in an unambiguous representation. The ISO 8601 standard
625defines YYYY-MM-DD as the date format, or YYYY-MM-DDTHH-MM-SS
626(that's a literal "T" separating the date from the time).
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
636280bd 774Mailing list: cpan-testers-discuss@perl.org
7ee27b7c
AT
775
776=item *
e41182b5 777
636280bd 778Testing results: http://www.cpantesters.org/
e41182b5
GS
779
780=back
781
e41182b5
GS
782=head1 PLATFORMS
783
784As of version 5.002, Perl is built with a C<$^O> variable that
785indicates the operating system it was built on. This was implemented
b7df3edc
GS
786to help speed up code that would otherwise have to C<use Config>
787and use the value of C<$Config{osname}>. Of course, to get more
e41182b5
GS
788detailed information about the system, looking into C<%Config> is
789certainly recommended.
790
b7df3edc
GS
791C<%Config> cannot always be trusted, however, because it was built
792at compile time. If perl was built in one place, then transferred
793elsewhere, some values may be wrong. The values may even have been
794edited after the fact.
6ab3f9cb 795
e41182b5
GS
796=head2 Unix
797
798Perl works on a bewildering variety of Unix and Unix-like platforms (see
799e.g. most of the files in the F<hints/> directory in the source code kit).
800On most of these systems, the value of C<$^O> (hence C<$Config{'osname'}>,
d1e3b762
GS
801too) is determined either by lowercasing and stripping punctuation from the
802first field of the string returned by typing C<uname -a> (or a similar command)
803at the shell prompt or by testing the file system for the presence of
804uniquely named files such as a kernel or header file. Here, for example,
805are a few of the more popular Unix flavors:
e41182b5 806
b7df3edc 807 uname $^O $Config{'archname'}
6ab3f9cb 808 --------------------------------------------
b7df3edc 809 AIX aix aix
6ab3f9cb 810 BSD/OS bsdos i386-bsdos
e1516da7 811 Darwin darwin darwin
6ab3f9cb
GS
812 dgux dgux AViiON-dgux
813 DYNIX/ptx dynixptx i386-dynixptx
b7df3edc 814 FreeBSD freebsd freebsd-i386
df00ff3b 815 Haiku haiku BePC-haiku
d1e3b762 816 Linux linux arm-linux
b7df3edc 817 Linux linux i386-linux
6ab3f9cb
GS
818 Linux linux i586-linux
819 Linux linux ppc-linux
b7df3edc
GS
820 HP-UX hpux PA-RISC1.1
821 IRIX irix irix
b787fad4 822 Mac OS X darwin darwin
d1e3b762
GS
823 NeXT 3 next next-fat
824 NeXT 4 next OPENSTEP-Mach
6ab3f9cb 825 openbsd openbsd i386-openbsd
b7df3edc 826 OSF1 dec_osf alpha-dec_osf
6ab3f9cb
GS
827 reliantunix-n svr4 RM400-svr4
828 SCO_SV sco_sv i386-sco_sv
829 SINIX-N svr4 RM400-svr4
830 sn4609 unicos CRAY_C90-unicos
831 sn6521 unicosmk t3e-unicosmk
832 sn9617 unicos CRAY_J90-unicos
b7df3edc
GS
833 SunOS solaris sun4-solaris
834 SunOS solaris i86pc-solaris
835 SunOS4 sunos sun4-sunos
e41182b5 836
b7df3edc
GS
837Because the value of C<$Config{archname}> may depend on the
838hardware architecture, it can vary more than the value of C<$^O>.
6ab3f9cb 839
e41182b5
GS
840=head2 DOS and Derivatives
841
b7df3edc 842Perl has long been ported to Intel-style microcomputers running under
e41182b5
GS
843systems like PC-DOS, MS-DOS, OS/2, and most Windows platforms you can
844bring yourself to mention (except for Windows CE, if you count that).
b7df3edc 845Users familiar with I<COMMAND.COM> or I<CMD.EXE> style shells should
e41182b5
GS
846be aware that each of these file specifications may have subtle
847differences:
848
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
JH
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
10fb90aa
PG
1162Perl on VOS (also known as OpenVOS) is discussed in F<README.vos>
1163in the perl distribution (installed as L<perlvos>). Perl on VOS
1164can accept either VOS- or Unix-style file specifications as in
1165either of the following:
495c5fdc 1166
ea8b8ad2
VP
1167 $ perl -ne "print if /perl_setup/i" >system>notices
1168 $ perl -ne "print if /perl_setup/i" /system/notices
495c5fdc
GP
1169
1170or even a mixture of both as in:
1171
ea8b8ad2 1172 $ perl -ne "print if /perl_setup/i" >system/notices
495c5fdc 1173
b7df3edc 1174Even though VOS allows the slash character to appear in object
495c5fdc 1175names, because the VOS port of Perl interprets it as a pathname
10fb90aa
PG
1176delimiting character, VOS files, directories, or links whose
1177names contain a slash character cannot be processed. Such files
1178must be renamed before they can be processed by Perl.
1179
1180Older releases of VOS (prior to OpenVOS Release 17.0) limit file
1181names to 32 or fewer characters, prohibit file names from
1182starting with a C<-> character, and prohibit file names from
1183containing any character matching C<< tr/ !#%&'()*;<=>?// >>.
1184
1185Newer releases of VOS (OpenVOS Release 17.0 or later) support a
1186feature known as extended names. On these releases, file names
1187can contain up to 255 characters, are prohibited from starting
1188with a C<-> character, and the set of prohibited characters is
1189reduced to any character matching C<< tr/#%*<>?// >>. There are
1190restrictions involving spaces and apostrophies: these characters
1191must not begin or end a name, nor can they immediately precede or
1192follow a period. Additionally, a space must not immediately
1193precede another space or hyphen. Specifically, the following
1194character combinations are prohibited: space-space,
1195space-hyphen, period-space, space-period, period-apostrophe,
1196apostrophe-period, leading or trailing space, and leading or
1197trailing apostrophe. Although an extended file name is limited
1198to 255 characters, a path name is still limited to 256
1199characters.
1200
1201The value of C<$^O> on VOS is "VOS". To determine the
1202architecture that you are running on without resorting to loading
1203all of C<%Config> you can examine the content of the @INC array
1204like so:
495c5fdc 1205
24e8e380 1206 if ($^O =~ /VOS/) {
495c5fdc
GP
1207 print "I'm on a Stratus box!\n";
1208 } else {
1209 print "I'm not on a Stratus box!\n";
1210 die;
1211 }
1212
495c5fdc
GP
1213Also see:
1214
1215=over 4
1216
c997b287 1217=item *
495c5fdc 1218
cc07ed0b 1219F<README.vos> (installed as L<perlvos>)
c997b287
GS
1220
1221=item *
1222
1223The VOS mailing list.
495c5fdc
GP
1224
1225There is no specific mailing list for Perl on VOS. You can post
10fb90aa
PG
1226comments to the comp.sys.stratus newsgroup, or use the contact
1227information located in the distribution files on the Stratus
1228Anonymous FTP site.
495c5fdc 1229
c997b287
GS
1230=item *
1231
cc07ed0b 1232VOS Perl on the web at http://ftp.stratus.com/pub/vos/posix/posix.html
495c5fdc
GP
1233
1234=back
1235
e41182b5
GS
1236=head2 EBCDIC Platforms
1237
1238Recent versions of Perl have been ported to platforms such as OS/400 on
d1e3b762
GS
1239AS/400 minicomputers as well as OS/390, VM/ESA, and BS2000 for S/390
1240Mainframes. Such computers use EBCDIC character sets internally (usually
0cc436d0
GS
1241Character Code Set ID 0037 for OS/400 and either 1047 or POSIX-BC for S/390
1242systems). On the mainframe perl currently works under the "Unix system
1243services for OS/390" (formerly known as OpenEdition), VM/ESA OpenEdition, or
1244the BS200 POSIX-BC system (BS2000 is supported in perl 5.6 and greater).
522b859a
JH
1245See L<perlos390> for details. Note that for OS/400 there is also a port of
1246Perl 5.8.1/5.9.0 or later to the PASE which is ASCII-based (as opposed to
1247ILE which is EBCDIC-based), see L<perlos400>.
e41182b5 1248
7c5ffed3
JH
1249As of R2.5 of USS for OS/390 and Version 2.3 of VM/ESA these Unix
1250sub-systems do not support the C<#!> shebang trick for script invocation.
1251Hence, on OS/390 and VM/ESA perl scripts can be executed with a header
1252similar to the following simple script:
e41182b5
GS
1253
1254 : # use perl
1255 eval 'exec /usr/local/bin/perl -S $0 ${1+"$@"}'
1256 if 0;
1257 #!/usr/local/bin/perl # just a comment really
1258
1259 print "Hello from perl!\n";
1260
d1e3b762
GS
1261OS/390 will support the C<#!> shebang trick in release 2.8 and beyond.
1262Calls to C<system> and backticks can use POSIX shell syntax on all
1263S/390 systems.
1264
b7df3edc 1265On the AS/400, if PERL5 is in your library list, you may need
6ab3f9cb
GS
1266to wrap your perl scripts in a CL procedure to invoke them like so:
1267
1268 BEGIN
1269 CALL PGM(PERL5/PERL) PARM('/QOpenSys/hello.pl')
1270 ENDPGM
1271
1272This will invoke the perl script F<hello.pl> in the root of the
1273QOpenSys file system. On the AS/400 calls to C<system> or backticks
1274must use CL syntax.
1275
e41182b5 1276On these platforms, bear in mind that the EBCDIC character set may have
0a47030a
GS
1277an effect on what happens with some perl functions (such as C<chr>,
1278C<pack>, C<print>, C<printf>, C<ord>, C<sort>, C<sprintf>, C<unpack>), as
1279well as bit-fiddling with ASCII constants using operators like C<^>, C<&>
1280and C<|>, not to mention dealing with socket interfaces to ASCII computers
6ab3f9cb 1281(see L<"Newlines">).
e41182b5 1282
b7df3edc
GS
1283Fortunately, most web servers for the mainframe will correctly
1284translate the C<\n> in the following statement to its ASCII equivalent
1285(C<\r> is the same under both Unix and OS/390 & VM/ESA):
e41182b5
GS
1286
1287 print "Content-type: text/html\r\n\r\n";
1288
d1e3b762 1289The values of C<$^O> on some of these platforms includes:
e41182b5 1290
d1e3b762
GS
1291 uname $^O $Config{'archname'}
1292 --------------------------------------------
1293 OS/390 os390 os390
1294 OS400 os400 os400
1295 POSIX-BC posix-bc BS2000-posix-bc
1296 VM/ESA vmesa vmesa
3c075c7d 1297
e41182b5
GS
1298Some simple tricks for determining if you are running on an EBCDIC
1299platform could include any of the following (perhaps all):
1300
ce7b6f06 1301 if ("\t" eq "\005") { print "EBCDIC may be spoken here!\n"; }
e41182b5
GS
1302
1303 if (ord('A') == 193) { print "EBCDIC may be spoken here!\n"; }
1304
1305 if (chr(169) eq 'z') { print "EBCDIC may be spoken here!\n"; }
1306
b7df3edc 1307One thing you may not want to rely on is the EBCDIC encoding
0a47030a
GS
1308of punctuation characters since these may differ from code page to code
1309page (and once your module or script is rumoured to work with EBCDIC,
1310folks will want it to work with all EBCDIC character sets).
e41182b5
GS
1311
1312Also see:
1313
1314=over 4
1315
c997b287
GS
1316=item *
1317
dc5c060f 1318L<perlos390>, F<README.os390>, F<perlbs2000>, F<README.vmesa>,
bb462878 1319L<perlebcdic>.
c997b287
GS
1320
1321=item *
e41182b5
GS
1322
1323The perl-mvs@perl.org list is for discussion of porting issues as well as
1324general usage issues for all EBCDIC Perls. Send a message body of
1325"subscribe perl-mvs" to majordomo@perl.org.
1326
7ee27b7c 1327=item *
c997b287
GS
1328
1329AS/400 Perl information at
b1866b2d 1330http://as400.rochester.ibm.com/
d1e3b762 1331as well as on CPAN in the F<ports/> directory.
e41182b5
GS
1332
1333=back
1334
b8099c3d
CN
1335=head2 Acorn RISC OS
1336
b7df3edc
GS
1337Because Acorns use ASCII with newlines (C<\n>) in text files as C<\012> like
1338Unix, and because Unix filename emulation is turned on by default,
1339most simple scripts will probably work "out of the box". The native
6ab3f9cb 1340filesystem is modular, and individual filesystems are free to be
0a47030a 1341case-sensitive or insensitive, and are usually case-preserving. Some
b7df3edc 1342native filesystems have name length limits, which file and directory
6ab3f9cb
GS
1343names are silently truncated to fit. Scripts should be aware that the
1344standard filesystem currently has a name length limit of B<10>
1345characters, with up to 77 items in a directory, but other filesystems
0a47030a 1346may not impose such limitations.
b8099c3d
CN
1347
1348Native filenames are of the form
1349
6ab3f9cb 1350 Filesystem#Special_Field::DiskName.$.Directory.Directory.File
dd9f0070 1351
b8099c3d
CN
1352where
1353
1354 Special_Field is not usually present, but may contain . and $ .
1355 Filesystem =~ m|[A-Za-z0-9_]|
1356 DsicName =~ m|[A-Za-z0-9_/]|
1357 $ represents the root directory
1358 . is the path separator
1359 @ is the current directory (per filesystem but machine global)
1360 ^ is the parent directory
1361 Directory and File =~ m|[^\0- "\.\$\%\&:\@\\^\|\177]+|
1362
1363The default filename translation is roughly C<tr|/.|./|;>
1364
6ab3f9cb 1365Note that C<"ADFS::HardDisk.$.File" ne 'ADFS::HardDisk.$.File'> and that
0a47030a
GS
1366the second stage of C<$> interpolation in regular expressions will fall
1367foul of the C<$.> if scripts are not careful.
1368
1369Logical paths specified by system variables containing comma-separated
b7df3edc 1370search lists are also allowed; hence C<System:Modules> is a valid
0a47030a 1371filename, and the filesystem will prefix C<Modules> with each section of
6ab3f9cb 1372C<System$Path> until a name is made that points to an object on disk.
b7df3edc 1373Writing to a new file C<System:Modules> would be allowed only if
0a47030a
GS
1374C<System$Path> contains a single item list. The filesystem will also
1375expand system variables in filenames if enclosed in angle brackets, so
c47ff5f1 1376C<< <System$Dir>.Modules >> would look for the file
0a47030a 1377S<C<$ENV{'System$Dir'} . 'Modules'>>. The obvious implication of this is
c47ff5f1 1378that B<fully qualified filenames can start with C<< <> >>> and should
0a47030a 1379be protected when C<open> is used for input.
b8099c3d
CN
1380
1381Because C<.> was in use as a directory separator and filenames could not
1382be assumed to be unique after 10 characters, Acorn implemented the C
1383compiler to strip the trailing C<.c> C<.h> C<.s> and C<.o> suffix from
1384filenames specified in source code and store the respective files in
b7df3edc 1385subdirectories named after the suffix. Hence files are translated:
b8099c3d
CN
1386
1387 foo.h h.foo
1388 C:foo.h C:h.foo (logical path variable)
1389 sys/os.h sys.h.os (C compiler groks Unix-speak)
1390 10charname.c c.10charname
1391 10charname.o o.10charname
1392 11charname_.c c.11charname (assuming filesystem truncates at 10)
1393
1394The Unix emulation library's translation of filenames to native assumes
b7df3edc
GS
1395that this sort of translation is required, and it allows a user-defined list
1396of known suffixes that it will transpose in this fashion. This may
1397seem transparent, but consider that with these rules C<foo/bar/baz.h>
0a47030a
GS
1398and C<foo/bar/h/baz> both map to C<foo.bar.h.baz>, and that C<readdir> and
1399C<glob> cannot and do not attempt to emulate the reverse mapping. Other
6ab3f9cb 1400C<.>'s in filenames are translated to C</>.
0a47030a 1401
b7df3edc 1402As implied above, the environment accessed through C<%ENV> is global, and
0a47030a 1403the convention is that program specific environment variables are of the
6ab3f9cb
GS
1404form C<Program$Name>. Each filesystem maintains a current directory,
1405and the current filesystem's current directory is the B<global> current
b7df3edc
GS
1406directory. Consequently, sociable programs don't change the current
1407directory but rely on full pathnames, and programs (and Makefiles) cannot
0a47030a
GS
1408assume that they can spawn a child process which can change the current
1409directory without affecting its parent (and everyone else for that
1410matter).
1411
b7df3edc
GS
1412Because native operating system filehandles are global and are currently
1413allocated down from 255, with 0 being a reserved value, the Unix emulation
0a47030a
GS
1414library emulates Unix filehandles. Consequently, you can't rely on
1415passing C<STDIN>, C<STDOUT>, or C<STDERR> to your children.
1416
1417The desire of users to express filenames of the form
c47ff5f1 1418C<< <Foo$Dir>.Bar >> on the command line unquoted causes problems,
0a47030a 1419too: C<``> command output capture has to perform a guessing game. It
c47ff5f1 1420assumes that a string C<< <[^<>]+\$[^<>]> >> is a
0a47030a 1421reference to an environment variable, whereas anything else involving
c47ff5f1 1422C<< < >> or C<< > >> is redirection, and generally manages to be 99%
0a47030a
GS
1423right. Of course, the problem remains that scripts cannot rely on any
1424Unix tools being available, or that any tools found have Unix-like command
1425line arguments.
1426
b7df3edc
GS
1427Extensions and XS are, in theory, buildable by anyone using free
1428tools. In practice, many don't, as users of the Acorn platform are
1429used to binary distributions. MakeMaker does run, but no available
1430make currently copes with MakeMaker's makefiles; even if and when
1431this should be fixed, the lack of a Unix-like shell will cause
1432problems with makefile rules, especially lines of the form C<cd
1433sdbm && make all>, and anything using quoting.
b8099c3d
CN
1434
1435"S<RISC OS>" is the proper name for the operating system, but the value
1436in C<$^O> is "riscos" (because we don't like shouting).
1437
e41182b5
GS
1438=head2 Other perls
1439
b7df3edc 1440Perl has been ported to many platforms that do not fit into any of
cd86ed9d
JV
1441the categories listed above. Some, such as AmigaOS, BeOS, HP MPE/iX,
1442QNX, Plan 9, and VOS, have been well-integrated into the standard
1443Perl source code kit. You may need to see the F<ports/> directory
1444on CPAN for information, and possibly binaries, for the likes of:
1445aos, Atari ST, lynxos, riscos, Novell Netware, Tandem Guardian,
1446I<etc.> (Yes, we know that some of these OSes may fall under the
1447Unix category, but we are not a standards body.)
e41182b5 1448
d1e3b762
GS
1449Some approximate operating system names and their C<$^O> values
1450in the "OTHER" category include:
1451
1452 OS $^O $Config{'archname'}
1453 ------------------------------------------
1454 Amiga DOS amigaos m68k-amigos
cec2c193 1455 BeOS beos
d1e3b762
GS
1456 MPE/iX mpeix PA-RISC1.1
1457
e41182b5
GS
1458See also:
1459
1460=over 4
1461
c997b287
GS
1462=item *
1463
1464Amiga, F<README.amiga> (installed as L<perlamiga>).
1465
1466=item *
d1e3b762 1467
c997b287 1468Be OS, F<README.beos>
e41182b5 1469
c997b287
GS
1470=item *
1471
1472HP 300 MPE/iX, F<README.mpeix> and Mark Bixby's web page
e59066d8 1473http://www.bixby.org/mark/porting.html
c997b287
GS
1474
1475=item *
e41182b5 1476
6ab3f9cb 1477A free perl5-based PERL.NLM for Novell Netware is available in
c997b287 1478precompiled binary and source code form from http://www.novell.com/
6ab3f9cb 1479as well as from CPAN.
e41182b5 1480
13a2d996 1481=item *
c997b287 1482
e6f03d26 1483S<Plan 9>, F<README.plan9>
d1e3b762 1484
e41182b5
GS
1485=back
1486
e41182b5
GS
1487=head1 FUNCTION IMPLEMENTATIONS
1488
b7df3edc
GS
1489Listed below are functions that are either completely unimplemented
1490or else have been implemented differently on various platforms.
1491Following each description will be, in parentheses, a list of
1492platforms that the description applies to.
e41182b5 1493
b7df3edc
GS
1494The list may well be incomplete, or even wrong in some places. When
1495in doubt, consult the platform-specific README files in the Perl
1496source distribution, and any other documentation resources accompanying
1497a given port.
e41182b5 1498
0a47030a 1499Be aware, moreover, that even among Unix-ish systems there are variations.
e41182b5 1500
b7df3edc
GS
1501For many functions, you can also query C<%Config>, exported by
1502default from the Config module. For example, to check whether the
1503platform has the C<lstat> call, check C<$Config{d_lstat}>. See
1504L<Config> for a full description of available variables.
e41182b5
GS
1505
1506=head2 Alphabetical Listing of Perl Functions
1507
1508=over 8
1509
e41182b5
GS
1510=item -X
1511
038ae9a4
SH
1512C<-w> only inspects the read-only file attribute (FILE_ATTRIBUTE_READONLY),
1513which determines whether the directory can be deleted, not whether it can
1514be written to. Directories always have read and write access unless denied
1515by discretionary access control lists (DACLs). (S<Win32>)
1516
b7df3edc
GS
1517C<-r>, C<-w>, C<-x>, and C<-o> tell whether the file is accessible,
1518which may not reflect UIC-based file protections. (VMS)
e41182b5 1519
b8099c3d
CN
1520C<-s> by name on an open file will return the space reserved on disk,
1521rather than the current extent. C<-s> on an open filehandle returns the
b7df3edc 1522current size. (S<RISC OS>)
b8099c3d 1523
e41182b5 1524C<-R>, C<-W>, C<-X>, C<-O> are indistinguishable from C<-r>, C<-w>,
204ad8d5 1525C<-x>, C<-o>. (Win32, VMS, S<RISC OS>)
e41182b5 1526
287a962e 1527C<-g>, C<-k>, C<-l>, C<-u>, C<-A> are not particularly meaningful.
b8099c3d 1528(Win32, VMS, S<RISC OS>)
e41182b5 1529
287a962e
JD
1530C<-p> is not particularly meaningful. (VMS, S<RISC OS>)
1531
e41182b5
GS
1532C<-d> is true if passed a device spec without an explicit directory.
1533(VMS)
1534
e41182b5 1535C<-x> (or C<-X>) determine if a file ends in one of the executable
b7df3edc 1536suffixes. C<-S> is meaningless. (Win32)
e41182b5 1537
b8099c3d
CN
1538C<-x> (or C<-X>) determine if a file has an executable file type.
1539(S<RISC OS>)
1540
aca72608
JD
1541=item alarm
1542
1543Emulated using timers that must be explicitly polled whenever Perl
1544wants to dispatch "safe signals" and therefore cannot interrupt
1545blocking system calls. (Win32)
1546
47cd99a4 1547=item atan2
519bc777
RGS
1548
1549Due to issues with various CPUs, math libraries, compilers, and standards,
1550results for C<atan2()> may vary depending on any combination of the above.
1551Perl attempts to conform to the Open Group/IEEE standards for the results
1552returned from C<atan2()>, but cannot force the issue if the system Perl is
1553run on does not allow it. (Tru64, HP-UX 10.20)
1554
1555The current version of the standards for C<atan2()> is available at
1556L<http://www.opengroup.org/onlinepubs/009695399/functions/atan2.html>.
1557
47cd99a4 1558=item binmode
e41182b5 1559
204ad8d5 1560Meaningless. (S<RISC OS>)
e41182b5
GS
1561
1562Reopens file and restores pointer; if function fails, underlying
1563filehandle may be closed, or pointer may be in a different position.
1564(VMS)
1565
1566The value returned by C<tell> may be affected after the call, and
1567the filehandle may be flushed. (Win32)
1568
47cd99a4 1569=item chmod
e41182b5 1570
e41182b5
GS
1571Only good for changing "owner" read-write access, "group", and "other"
1572bits are meaningless. (Win32)
1573
b8099c3d
CN
1574Only good for changing "owner" and "other" read-write access. (S<RISC OS>)
1575
495c5fdc
GP
1576Access permissions are mapped onto VOS access-control list changes. (VOS)
1577
4e51f8e4 1578The actual permissions set depend on the value of the C<CYGWIN>
789f0d36 1579in the SYSTEM environment settings. (Cygwin)
4e51f8e4 1580
47cd99a4 1581=item chown
e41182b5 1582
204ad8d5 1583Not implemented. (Win32, S<Plan 9>, S<RISC OS>)
e41182b5
GS
1584
1585Does nothing, but won't fail. (Win32)
1586
3fd80bd6
PG
1587A little funky, because VOS's notion of ownership is a little funky (VOS).
1588
e41182b5
GS
1589=item chroot
1590
204ad8d5 1591Not implemented. (Win32, VMS, S<Plan 9>, S<RISC OS>, VOS, VM/ESA)
e41182b5 1592
47cd99a4 1593=item crypt
e41182b5
GS
1594
1595May not be available if library or source was not provided when building
b8099c3d 1596perl. (Win32)
e41182b5 1597
47cd99a4 1598=item dbmclose
e41182b5 1599
e6f03d26 1600Not implemented. (VMS, S<Plan 9>, VOS)
e41182b5 1601
47cd99a4 1602=item dbmopen
e41182b5 1603
e6f03d26 1604Not implemented. (VMS, S<Plan 9>, VOS)
e41182b5 1605
47cd99a4 1606=item dump
e41182b5 1607
204ad8d5 1608Not useful. (S<RISC OS>)
e41182b5 1609
84d78eb7 1610Not supported. (Cygwin, Win32)
e41182b5 1611
b8099c3d 1612Invokes VMS debugger. (VMS)
e41182b5 1613
47cd99a4 1614=item exec
e41182b5 1615
7c5ffed3 1616Implemented via Spawn. (VM/ESA)
3c075c7d 1617
0f897271
GS
1618Does not automatically flush output handles on some platforms.
1619(SunOS, Solaris, HP-UX)
1620
fe12c0e8
MS
1621=item exit
1622
e1020413 1623Emulates Unix exit() (which considers C<exit 1> to indicate an error) by
fe12c0e8
MS
1624mapping the C<1> to SS$_ABORT (C<44>). This behavior may be overridden
1625with the pragma C<use vmsish 'exit'>. As with the CRTL's exit()
1626function, C<exit 0> is also mapped to an exit status of SS$_NORMAL
1627(C<1>); this mapping cannot be overridden. Any other argument to exit()
016930a6
JM
1628is used directly as Perl's exit status. On VMS, unless the future
1629POSIX_EXIT mode is enabled, the exit code should always be a valid
1630VMS exit code and not a generic number. When the POSIX_EXIT mode is
1631enabled, a generic number will be encoded in a method compatible with
1632the C library _POSIX_EXIT macro so that it can be decoded by other
1633programs, particularly ones written in C, like the GNV package. (VMS)
fe12c0e8 1634
47cd99a4 1635=item fcntl
e41182b5 1636
016930a6
JM
1637Not implemented. (Win32)
1638Some functions available based on the version of VMS. (VMS)
e41182b5 1639
47cd99a4 1640=item flock
e41182b5 1641
204ad8d5 1642Not implemented (VMS, S<RISC OS>, VOS).
e41182b5
GS
1643
1644Available only on Windows NT (not on Windows 95). (Win32)
1645
1646=item fork
1647
204ad8d5 1648Not implemented. (AmigaOS, S<RISC OS>, VM/ESA, VMS)
0f897271
GS
1649
1650Emulated using multiple interpreters. See L<perlfork>. (Win32)
1651
1652Does not automatically flush output handles on some platforms.
1653(SunOS, Solaris, HP-UX)
e41182b5
GS
1654
1655=item getlogin
1656
204ad8d5 1657Not implemented. (S<RISC OS>)
e41182b5 1658
47cd99a4 1659=item getpgrp
e41182b5 1660
204ad8d5 1661Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5
GS
1662
1663=item getppid
1664
204ad8d5 1665Not implemented. (Win32, S<RISC OS>)
e41182b5 1666
47cd99a4 1667=item getpriority
e41182b5 1668
204ad8d5 1669Not implemented. (Win32, VMS, S<RISC OS>, VOS, VM/ESA)
e41182b5 1670
47cd99a4 1671=item getpwnam
e41182b5 1672
204ad8d5 1673Not implemented. (Win32)
e41182b5 1674
b8099c3d
CN
1675Not useful. (S<RISC OS>)
1676
47cd99a4 1677=item getgrnam
e41182b5 1678
204ad8d5 1679Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5 1680
47cd99a4 1681=item getnetbyname
e41182b5 1682
204ad8d5 1683Not implemented. (Win32, S<Plan 9>)
e41182b5 1684
47cd99a4 1685=item getpwuid
e41182b5 1686
204ad8d5 1687Not implemented. (Win32)
e41182b5 1688
b8099c3d
CN
1689Not useful. (S<RISC OS>)
1690
47cd99a4 1691=item getgrgid
e41182b5 1692
204ad8d5 1693Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5 1694
47cd99a4 1695=item getnetbyaddr
e41182b5 1696
204ad8d5 1697Not implemented. (Win32, S<Plan 9>)
e41182b5 1698
47cd99a4 1699=item getprotobynumber
e41182b5 1700
47cd99a4 1701=item getservbyport
e41182b5 1702
e41182b5
GS
1703=item getpwent
1704
204ad8d5 1705Not implemented. (Win32, VM/ESA)
e41182b5
GS
1706
1707=item getgrent
1708
204ad8d5 1709Not implemented. (Win32, VMS, VM/ESA)
e41182b5 1710
ef5a6dd7
JH
1711=item gethostbyname
1712
1713C<gethostbyname('localhost')> does not work everywhere: you may have
204ad8d5 1714to use C<gethostbyname('127.0.0.1')>. (S<Irix 5>)
ef5a6dd7 1715
e41182b5
GS
1716=item gethostent
1717
204ad8d5 1718Not implemented. (Win32)
e41182b5
GS
1719
1720=item getnetent
1721
204ad8d5 1722Not implemented. (Win32, S<Plan 9>)
e41182b5
GS
1723
1724=item getprotoent
1725
204ad8d5 1726Not implemented. (Win32, S<Plan 9>)
e41182b5
GS
1727
1728=item getservent
1729
e6f03d26 1730Not implemented. (Win32, S<Plan 9>)
e41182b5 1731
47cd99a4 1732=item sethostent
e41182b5 1733
204ad8d5 1734Not implemented. (Win32, S<Plan 9>, S<RISC OS>)
e41182b5 1735
47cd99a4 1736=item setnetent
e41182b5 1737
204ad8d5 1738Not implemented. (Win32, S<Plan 9>, S<RISC OS>)
e41182b5 1739
47cd99a4 1740=item setprotoent
e41182b5 1741
204ad8d5 1742Not implemented. (Win32, S<Plan 9>, S<RISC OS>)
e41182b5 1743
47cd99a4 1744=item setservent
e41182b5 1745
e6f03d26 1746Not implemented. (S<Plan 9>, Win32, S<RISC OS>)
e41182b5
GS
1747
1748=item endpwent
1749
204ad8d5 1750Not implemented. (MPE/iX, VM/ESA, Win32)
e41182b5
GS
1751
1752=item endgrent
1753
204ad8d5 1754Not implemented. (MPE/iX, S<RISC OS>, VM/ESA, VMS, Win32)
e41182b5
GS
1755
1756=item endhostent
1757
204ad8d5 1758Not implemented. (Win32)
e41182b5
GS
1759
1760=item endnetent
1761
204ad8d5 1762Not implemented. (Win32, S<Plan 9>)
e41182b5
GS
1763
1764=item endprotoent
1765
204ad8d5 1766Not implemented. (Win32, S<Plan 9>)
e41182b5
GS
1767
1768=item endservent
1769
e6f03d26 1770Not implemented. (S<Plan 9>, Win32)
e41182b5
GS
1771
1772=item getsockopt SOCKET,LEVEL,OPTNAME
1773
e6f03d26 1774Not implemented. (S<Plan 9>)
e41182b5 1775
e41182b5
GS
1776=item glob
1777
63f87e49
GS
1778This operator is implemented via the File::Glob extension on most
1779platforms. See L<File::Glob> for portability information.
b8099c3d 1780
62aa5637
MS
1781=item gmtime
1782
461d5a49
MS
1783In theory, gmtime() is reliable from -2**63 to 2**63-1. However,
1784because work arounds in the implementation use floating point numbers,
1785it will become inaccurate as the time gets larger. This is a bug and
1786will be fixed in the future.
62aa5637 1787
10fb90aa
PG
1788On VOS, time values are 32-bit quantities.
1789
e41182b5
GS
1790=item ioctl FILEHANDLE,FUNCTION,SCALAR
1791
1792Not implemented. (VMS)
1793
1794Available only for socket handles, and it does what the ioctlsocket() call
1795in the Winsock API does. (Win32)
1796
b8099c3d
CN
1797Available only for socket handles. (S<RISC OS>)
1798
47cd99a4 1799=item kill
e41182b5 1800
862b5365 1801Not implemented, hence not useful for taint checking. (S<RISC OS>)
e41182b5 1802
63f87e49
GS
1803C<kill()> doesn't have the semantics of C<raise()>, i.e. it doesn't send
1804a signal to the identified process like it does on Unix platforms.
1805Instead C<kill($sig, $pid)> terminates the process identified by $pid,
1806and makes it exit immediately with exit status $sig. As in Unix, if
1807$sig is 0 and the specified process exists, it returns true without
1808actually terminating it. (Win32)
e41182b5 1809
d0302514
JD
1810C<kill(-9, $pid)> will terminate the process specified by $pid and
1811recursively all child processes owned by it. This is different from
1812the Unix semantics, where the signal will be delivered to all
1813processes in the same process group as the process specified by
1814$pid. (Win32)
1815
016930a6
JM
1816Is not supported for process identification number of 0 or negative
1817numbers. (VMS)
1818
47cd99a4 1819=item link
e41182b5 1820
10fb90aa 1821Not implemented. (MPE/iX, S<RISC OS>, VOS)
e41182b5 1822
433acd8a
JH
1823Link count not updated because hard links are not quite that hard
1824(They are sort of half-way between hard and soft links). (AmigaOS)
1825
63d6c08b
JD
1826Hard links are implemented on Win32 under NTFS only. They are
1827natively supported on Windows 2000 and later. On Windows NT they
1828are implemented using the Windows POSIX subsystem support and the
1829Perl process will need Administrator or Backup Operator privileges
1830to create hard links.
a3dfe201 1831
016930a6
JM
1832Available on 64 bit OpenVMS 8.2 and later. (VMS)
1833
62aa5637
MS
1834=item localtime
1835
a61fc69c 1836localtime() has the same range as L</gmtime>, but because time zone
dc164757
MS
1837rules change its accuracy for historical and future times may degrade
1838but usually by no more than an hour.
62aa5637 1839
e41182b5
GS
1840=item lstat
1841
016930a6 1842Not implemented. (S<RISC OS>)
e41182b5 1843
63f87e49 1844Return values (especially for device and inode) may be bogus. (Win32)
e41182b5 1845
47cd99a4 1846=item msgctl
e41182b5 1847
47cd99a4 1848=item msgget
e41182b5 1849
47cd99a4 1850=item msgsnd
e41182b5 1851
47cd99a4 1852=item msgrcv
e41182b5 1853
204ad8d5 1854Not implemented. (Win32, VMS, S<Plan 9>, S<RISC OS>, VOS)
e41182b5 1855
47cd99a4 1856=item open
e41182b5 1857
204ad8d5 1858open to C<|-> and C<-|> are unsupported. (Win32, S<RISC OS>)
e41182b5 1859
0f897271
GS
1860Opening a process does not automatically flush output handles on some
1861platforms. (SunOS, Solaris, HP-UX)
1862
e41182b5
GS
1863=item readlink
1864
b8099c3d 1865Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5 1866
47cd99a4 1867=item rename
c9b2b9d4
SS
1868
1869Can't move directories between directories on different logical volumes. (Win32)
1870
3ba4b5c1
JD
1871=item rewinddir
1872
1873Will not cause readdir() to re-read the directory stream. The entries
1874already read before the rewinddir() call will just be returned again
1875from a cache buffer. (Win32)
1876
47cd99a4 1877=item select
e41182b5 1878
689c5c24 1879Only implemented on sockets. (Win32, VMS)
e41182b5 1880
b8099c3d
CN
1881Only reliable on sockets. (S<RISC OS>)
1882
76e05f0b 1883Note that the C<select FILEHANDLE> form is generally portable.
63f87e49 1884
47cd99a4 1885=item semctl
e41182b5 1886
47cd99a4 1887=item semget
e41182b5 1888
47cd99a4 1889=item semop
e41182b5 1890
10fb90aa 1891Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5 1892
a3dfe201
GS
1893=item setgrent
1894
10fb90aa 1895Not implemented. (MPE/iX, VMS, Win32, S<RISC OS>)
a3dfe201 1896
47cd99a4 1897=item setpgrp
e41182b5 1898
204ad8d5 1899Not implemented. (Win32, VMS, S<RISC OS>, VOS)
e41182b5 1900
47cd99a4 1901=item setpriority
e41182b5 1902
204ad8d5 1903Not implemented. (Win32, VMS, S<RISC OS>, VOS)
e41182b5 1904
a3dfe201
GS
1905=item setpwent
1906
10fb90aa 1907Not implemented. (MPE/iX, Win32, S<RISC OS>)
a3dfe201 1908
47cd99a4 1909=item setsockopt
e41182b5 1910
e6f03d26 1911Not implemented. (S<Plan 9>)
e41182b5 1912
47cd99a4 1913=item shmctl
e41182b5 1914
47cd99a4 1915=item shmget
e41182b5 1916
47cd99a4 1917=item shmread
e41182b5 1918
47cd99a4 1919=item shmwrite
e41182b5 1920
204ad8d5 1921Not implemented. (Win32, VMS, S<RISC OS>, VOS)
e41182b5 1922
47cd99a4 1923=item sockatmark
80cbd5ad
JH
1924
1925A relatively recent addition to socket functions, may not
e1020413 1926be implemented even in Unix platforms.
80cbd5ad 1927
47cd99a4 1928=item socketpair
e41182b5 1929
10fb90aa
PG
1930Not implemented. (S<RISC OS>, VM/ESA)
1931
1932Available on OpenVOS Release 17.0 or later. (VOS)
016930a6
JM
1933
1934Available on 64 bit OpenVMS 8.2 and later. (VMS)
e41182b5 1935
e41182b5
GS
1936=item stat
1937
d62e1b7f
JH
1938Platforms that do not have rdev, blksize, or blocks will return these
1939as '', so numeric comparison or manipulation of these fields may cause
1940'not numeric' warnings.
1941
3f1f789b 1942ctime not supported on UFS (S<Mac OS X>).
e41182b5 1943
95a3fe12
MS
1944ctime is creation time instead of inode change time (Win32).
1945
e41182b5
GS
1946device and inode are not meaningful. (Win32)
1947
1948device and inode are not necessarily reliable. (VMS)
1949
b8099c3d
CN
1950mtime, atime and ctime all return the last modification time. Device and
1951inode are not necessarily reliable. (S<RISC OS>)
1952
d62e1b7f
JH
1953dev, rdev, blksize, and blocks are not available. inode is not
1954meaningful and will differ between stat calls on the same file. (os2)
1955
73e9292c
JH
1956some versions of cygwin when doing a stat("foo") and if not finding it
1957may then attempt to stat("foo.exe") (Cygwin)
1958
1fafdf34
JD
1959On Win32 stat() needs to open the file to determine the link count
1960and update attributes that may have been changed through hard links.
1961Setting ${^WIN32_SLOPPY_STAT} to a true value speeds up stat() by
1962not performing this operation. (Win32)
1963
47cd99a4 1964=item symlink
e41182b5 1965
c73b03b7
JM
1966Not implemented. (Win32, S<RISC OS>)
1967
1968Implemented on 64 bit VMS 8.3. VMS requires the symbolic link to be in Unix
1969syntax if it is intended to resolve to a valid path.
e41182b5 1970
47cd99a4 1971=item syscall
e41182b5 1972
204ad8d5 1973Not implemented. (Win32, VMS, S<RISC OS>, VOS, VM/ESA)
e41182b5 1974
47cd99a4 1975=item sysopen
f34d0673 1976
dd9f0070 1977The traditional "0", "1", and "2" MODEs are implemented with different
322422de
GS
1978numeric values on some systems. The flags exported by C<Fcntl>
1979(O_RDONLY, O_WRONLY, O_RDWR) should work everywhere though. (S<Mac
7c5ffed3 1980OS>, OS/390, VM/ESA)
f34d0673 1981
47cd99a4 1982=item system
e41182b5 1983
e41182b5 1984As an optimization, may not call the command shell specified in
b7df3edc 1985C<$ENV{PERL5SHELL}>. C<system(1, @args)> spawns an external
e41182b5
GS
1986process and immediately returns its process designator, without
1987waiting for it to terminate. Return value may be used subsequently
63f87e49
GS
1988in C<wait> or C<waitpid>. Failure to spawn() a subprocess is indicated
1989by setting $? to "255 << 8". C<$?> is set in a way compatible with
1990Unix (i.e. the exitstatus of the subprocess is obtained by "$? >> 8",
1991as described in the documentation). (Win32)
e41182b5 1992
b8099c3d
CN
1993There is no shell to process metacharacters, and the native standard is
1994to pass a command line terminated by "\n" "\r" or "\0" to the spawned
c47ff5f1 1995program. Redirection such as C<< > foo >> is performed (if at all) by
b8099c3d
CN
1996the run time library of the spawned program. C<system> I<list> will call
1997the Unix emulation library's C<exec> emulation, which attempts to provide
1998emulation of the stdin, stdout, stderr in force in the parent, providing
1999the child program uses a compatible version of the emulation library.
2000I<scalar> will call the native command line direct and no such emulation
2001of a child Unix program will exists. Mileage B<will> vary. (S<RISC OS>)
2002
0f897271
GS
2003Does not automatically flush output handles on some platforms.
2004(SunOS, Solaris, HP-UX)
2005
9bc98430
CB
2006The return value is POSIX-like (shifted up by 8 bits), which only allows
2007room for a made-up value derived from the severity bits of the native
200832-bit condition code (unless overridden by C<use vmsish 'status'>).
016930a6
JM
2009If the native condition code is one that has a POSIX value encoded, the
2010POSIX value will be decoded to extract the expected exit value.
9bc98430
CB
2011For more details see L<perlvms/$?>. (VMS)
2012
e41182b5
GS
2013=item times
2014
63f87e49
GS
2015"cumulative" times will be bogus. On anything other than Windows NT
2016or Windows 2000, "system" time will be bogus, and "user" time is
2017actually the time returned by the clock() function in the C runtime
2018library. (Win32)
e41182b5 2019
b8099c3d
CN
2020Not useful. (S<RISC OS>)
2021
47cd99a4 2022=item truncate
e41182b5 2023
6d738113 2024Not implemented. (Older versions of VMS)
e41182b5 2025
3fd80bd6 2026Truncation to same-or-shorter lengths only. (VOS)
495c5fdc 2027
4cfdb94f 2028If a FILEHANDLE is supplied, it must be writable and opened in append
e71a7dc8 2029mode (i.e., use C<<< open(FH, '>>filename') >>>
4cfdb94f
GS
2030or C<sysopen(FH,...,O_APPEND|O_RDWR)>. If a filename is supplied, it
2031should not be held open elsewhere. (Win32)
2032
e41182b5
GS
2033=item umask
2034
2035Returns undef where unavailable, as of version 5.005.
2036
b7df3edc
GS
2037C<umask> works but the correct permissions are set only when the file
2038is finally closed. (AmigaOS)
433acd8a 2039
47cd99a4 2040=item utime
e41182b5 2041
204ad8d5 2042Only the modification time is updated. (S<BeOS>, VMS, S<RISC OS>)
e41182b5 2043
322422de
GS
2044May not behave as expected. Behavior depends on the C runtime
2045library's implementation of utime(), and the filesystem being
2046used. The FAT filesystem typically does not support an "access
2047time" field, and it may limit timestamps to a granularity of
2048two seconds. (Win32)
e41182b5
GS
2049
2050=item wait
2051
47cd99a4 2052=item waitpid
e41182b5 2053
e41182b5 2054Can only be applied to process handles returned for processes spawned
a6f858fb 2055using C<system(1, ...)> or pseudo processes created with C<fork()>. (Win32)
e41182b5 2056
b8099c3d
CN
2057Not useful. (S<RISC OS>)
2058
e41182b5
GS
2059=back
2060
2061
7c35b6af 2062=head1 Supported Platforms
ba58ab26 2063
7c35b6af
RGS
2064The following platforms are known to build Perl 5.12 (as of April 2010,
2065its release date) from the standard source code distribution available
bb377ba2
JV
2066at http://www.cpan.org/src
2067
bb377ba2
JV
2068=over
2069
2070=item Linux (x86, ARM, IA64)
2071
e0d9a2c8 2072=item HP-UX
bb377ba2
JV
2073
2074=item AIX
2075
2076=item Win32
2077
2078=over
2079
2080=item Windows 2000
2081
2082=item Windows XP
2083
2084=item Windows Server 2003
2085
2086=item Windows Vista
2087
2088=item Windows Server 2008
2089
3b665c47
JD
2090=item Windows 7
2091
bb377ba2
JV
2092=back
2093
2d9ede6e
JH
2094=item Cygwin
2095
bb377ba2
JV
2096=item Solaris (x86, SPARC)
2097
1b0ab010
JV
2098=item OpenVMS
2099
2100=over
2101
2102=item Alpha (7.2 and later)
2103
2104=item I64 (8.2 and later)
2105
2106=back
bb377ba2
JV
2107
2108=item Symbian
2109
2110=item NetBSD
2111
2112=item FreeBSD
2113
2114=item Haiku
2115
2116=item Irix (6.5. What else?)
2117
2118=item OpenBSD
2119
2120=item Dragonfly BSD
2121
a62bfce3
CBW
2122=item QNX Neutrino RTOS (6.5.0)
2123
bb377ba2
JV
2124=item MirOS BSD
2125
2126Caveats:
2127
2128=over
2129
2130=item time_t issues that may or may not be fixed
2131
2132=back
2133
2134
2135=item Symbian (Series 60 v3, 3.2 and 5 - what else?)
2136
10fb90aa 2137=item Stratus VOS / OpenVOS
bb377ba2
JV
2138
2139=item AIX
2140
2141=back
2142
2143=head1 EOL Platforms (Perl 5.12)
2144
2145The following platforms were supported by a previous version of
2146Perl but have been officially removed from Perl's source code
2147as of 5.12:
2148
2149=over
2150
2151=item Atari MiNT
2152
2153=item Apollo Domain/OS
2154
2155=item Apple Mac OS 8/9
2156
2157=item Tenon Machten
2158
2159=back
2160
2161The following platforms may still work as of Perl 5.12, but Perl's
2162developers have made an explicit decision to discontinue support for
2163them:
2164
2165=over
2166
2167=item Windows 95
2168
2169=item Windows 98
2170
2171=item Windows ME
2172
2173=item Windows NT4
2174
2175=back
2176
2177=head1 Supported Platforms (Perl 5.8)
2178
2179As of July 2002 (the Perl release 5.8.0), the following platforms were
cec2c193 2180able to build Perl from the standard source code distribution
e59066d8 2181available at http://www.cpan.org/src/
cec2c193
JH
2182
2183 AIX
2184 BeOS
6f683aa2 2185 BSD/OS (BSDi)
cec2c193
JH
2186 Cygwin
2187 DG/UX
811b48f2 2188 DOS DJGPP 1)
cec2c193
JH
2189 DYNIX/ptx
2190 EPOC R5
2191 FreeBSD
6f683aa2 2192 HI-UXMPP (Hitachi) (5.8.0 worked but we didn't know it)
cec2c193
JH
2193 HP-UX
2194 IRIX
2195 Linux
8939ba94 2196 Mac OS Classic
6f683aa2 2197 Mac OS X (Darwin)
cec2c193
JH
2198 MPE/iX
2199 NetBSD
2200 NetWare
2201 NonStop-UX
6f683aa2 2202 ReliantUNIX (formerly SINIX)
cec2c193 2203 OpenBSD
6f683aa2 2204 OpenVMS (formerly VMS)
3ebac25b 2205 Open UNIX (Unixware) (since Perl 5.8.1/5.9.0)
cec2c193 2206 OS/2
522b859a 2207 OS/400 (using the PASE) (since Perl 5.8.1/5.9.0)
70de81db 2208 PowerUX
6f683aa2 2209 POSIX-BC (formerly BS2000)
cec2c193
JH
2210 QNX
2211 Solaris
70de81db 2212 SunOS 4
6f683aa2
JH
2213 SUPER-UX (NEC)
2214 Tru64 UNIX (formerly DEC OSF/1, Digital UNIX)
cec2c193
JH
2215 UNICOS
2216 UNICOS/mk
2217 UTS
2218 VOS
811b48f2 2219 Win95/98/ME/2K/XP 2)
c40b5d1d 2220 WinCE
6f683aa2 2221 z/OS (formerly OS/390)
cec2c193 2222 VM/ESA
ba58ab26 2223
811b48f2
JH
2224 1) in DOS mode either the DOS or OS/2 ports can be used
2225 2) compilers: Borland, MinGW (GCC), VC6
cec2c193 2226
c40b5d1d 2227The following platforms worked with the previous releases (5.6 and
cec2c193
JH
22285.7), but we did not manage either to fix or to test these in time
2229for the 5.8.0 release. There is a very good chance that many of these
70de81db 2230will work fine with the 5.8.0.
cec2c193 2231
8da2b1be 2232 BSD/OS
cec2c193
JH
2233 DomainOS
2234 Hurd
2235 LynxOS
2236 MachTen
2237 PowerMAX
2238 SCO SV
cec2c193
JH
2239 SVR4
2240 Unixware
2241 Windows 3.1
ba58ab26 2242
70de81db
JH
2243Known to be broken for 5.8.0 (but 5.6.1 and 5.7.2 can be used):
2244
2245 AmigaOS
2246
ba58ab26 2247The following platforms have been known to build Perl from source in
fd46a41b
JH
2248the past (5.005_03 and earlier), but we haven't been able to verify
2249their status for the current release, either because the
2250hardware/software platforms are rare or because we don't have an
2251active champion on these platforms--or both. They used to work,
2252though, so go ahead and try compiling them, and let perlbug@perl.org
2253of any trouble.
ba58ab26 2254
cec2c193
JH
2255 3b1
2256 A/UX
cec2c193
JH
2257 ConvexOS
2258 CX/UX
2259 DC/OSx
2260 DDE SMES
2261 DOS EMX
2262 Dynix
2263 EP/IX
2264 ESIX
2265 FPS
2266 GENIX
2267 Greenhills
2268 ISC
2269 MachTen 68k
cec2c193
JH
2270 MPC
2271 NEWS-OS
2272 NextSTEP
2273 OpenSTEP
2274 Opus
2275 Plan 9
cec2c193 2276 RISC/os
8da2b1be 2277 SCO ODT/OSR
cec2c193
JH
2278 Stellar
2279 SVR2
2280 TI1500
2281 TitanOS
2282 Ultrix
2283 Unisys Dynix
ba58ab26
JH
2284
2285The following platforms have their own source code distributions and
1577cd80 2286binaries available via http://www.cpan.org/ports/
ba58ab26 2287
cec2c193 2288 Perl release
ba58ab26 2289
522b859a 2290 OS/400 (ILE) 5.005_02
cec2c193 2291 Tandem Guardian 5.004
ba58ab26
JH
2292
2293The following platforms have only binaries available via
a93751fa 2294http://www.cpan.org/ports/index.html :
ba58ab26 2295
cec2c193 2296 Perl release
ba58ab26 2297
cec2c193
JH
2298 Acorn RISCOS 5.005_02
2299 AOS 5.002
2300 LynxOS 5.004_02
ba58ab26
JH
2301
2302Although we do suggest that you always build your own Perl from
2303the source code, both for maximal configurability and for security,
2304in case you are in a hurry you can check
a93751fa 2305http://www.cpan.org/ports/index.html for binary distributions.
ba58ab26 2306
c997b287
GS
2307=head1 SEE ALSO
2308
cec2c193 2309L<perlaix>, L<perlamiga>, L<perlapollo>, L<perlbeos>, L<perlbs2000>,
18a271bd 2310L<perlce>, L<perlcygwin>, L<perldgux>, L<perldos>, L<perlepoc>,
469e7be4 2311L<perlebcdic>, L<perlfreebsd>, L<perlhurd>, L<perlhpux>, L<perlirix>,
e94c1c05 2312L<perlmacos>, L<perlmacosx>, L<perlmpeix>,
522b859a
JH
2313L<perlnetware>, L<perlos2>, L<perlos390>, L<perlos400>,
2314L<perlplan9>, L<perlqnx>, L<perlsolaris>, L<perltru64>,
2315L<perlunicode>, L<perlvmesa>, L<perlvms>, L<perlvos>,
2316L<perlwin32>, and L<Win32>.
c997b287 2317
e41182b5
GS
2318=head1 AUTHORS / CONTRIBUTORS
2319
06e9666b 2320Abigail <abigail@foad.org>,
c47ff5f1
GS
2321Charles Bailey <bailey@newman.upenn.edu>,
2322Graham Barr <gbarr@pobox.com>,
2323Tom Christiansen <tchrist@perl.com>,
06e9666b 2324Nicholas Clark <nick@ccl4.org>,
c47ff5f1 2325Thomas Dorner <Thomas.Dorner@start.de>,
06e9666b
A
2326Andy Dougherty <doughera@lafayette.edu>,
2327Dominic Dunlop <domo@computer.org>,
2328Neale Ferguson <neale@vma.tabnsw.com.au>,
c47ff5f1 2329David J. Fiander <davidf@mks.com>,
3fd80bd6 2330Paul Green <Paul.Green@stratus.com>,
06e9666b 2331M.J.T. Guy <mjtg@cam.ac.uk>,
61f30a5e 2332Jarkko Hietaniemi <jhi@iki.fi>,
c47ff5f1 2333Luther Huffman <lutherh@stratcom.com>,
06e9666b
A
2334Nick Ing-Simmons <nick@ing-simmons.net>,
2335Andreas J. KE<ouml>nig <a.koenig@mind.de>,
c47ff5f1
GS
2336Markus Laker <mlaker@contax.co.uk>,
2337Andrew M. Langmead <aml@world.std.com>,
2338Larry Moore <ljmoore@freespace.net>,
2339Paul Moore <Paul.Moore@uk.origin-it.com>,
2340Chris Nandor <pudge@pobox.com>,
1afc07ec 2341Matthias Neeracher <neeracher@mac.com>,
e71a7dc8 2342Philip Newton <pne@cpan.org>,
c47ff5f1
GS
2343Gary Ng <71564.1743@CompuServe.COM>,
2344Tom Phoenix <rootbeer@teleport.com>,
2345AndrE<eacute> Pirard <A.Pirard@ulg.ac.be>,
2346Peter Prymmer <pvhp@forte.com>,
2347Hugo van der Sanden <hv@crypt0.demon.co.uk>,
2348Gurusamy Sarathy <gsar@activestate.com>,
2349Paul J. Schinder <schinder@pobox.com>,
2350Michael G Schwern <schwern@pobox.com>,
06e9666b 2351Dan Sugalski <dan@sidhe.org>,
c47ff5f1 2352Nathan Torkington <gnat@frii.com>.
016930a6 2353John Malmberg <wb8tyw@qsl.net>