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1=head1 NAME
2
3perlport - Writing portable Perl
4
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5=head1 DESCRIPTION
6
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7Perl runs on numerous operating systems. While most of them share
8much in common, they also have their own unique features.
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9
10This document is meant to help you to find out what constitutes portable
b7df3edc 11Perl code. That way once you make a decision to write portably,
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12you know where the lines are drawn, and you can stay within them.
13
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14There is a tradeoff between taking full advantage of one particular
15type of computer and taking advantage of a full range of them.
16Naturally, as you broaden your range and become more diverse, the
17common factors drop, and you are left with an increasingly smaller
18area of common ground in which you can operate to accomplish a
19particular task. Thus, when you begin attacking a problem, it is
20important to consider under which part of the tradeoff curve you
21want to operate. Specifically, you must decide whether it is
22important that the task that you are coding have the full generality
23of being portable, or whether to just get the job done right now.
24This is the hardest choice to be made. The rest is easy, because
25Perl provides many choices, whichever way you want to approach your
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26problem.
27
28Looking at it another way, writing portable code is usually about
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29willfully limiting your available choices. Naturally, it takes
30discipline and sacrifice to do that. The product of portability
31and convenience may be a constant. You have been warned.
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32
33Be aware of two important points:
34
35=over 4
36
37=item Not all Perl programs have to be portable
38
b7df3edc 39There is no reason you should not use Perl as a language to glue Unix
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40tools together, or to prototype a Macintosh application, or to manage the
41Windows registry. If it makes no sense to aim for portability for one
42reason or another in a given program, then don't bother.
43
b7df3edc 44=item Nearly all of Perl already I<is> portable
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45
46Don't be fooled into thinking that it is hard to create portable Perl
47code. It isn't. Perl tries its level-best to bridge the gaps between
48what's available on different platforms, and all the means available to
49use those features. Thus almost all Perl code runs on any machine
6ab3f9cb 50without modification. But there are some significant issues in
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51writing portable code, and this document is entirely about those issues.
52
53=back
54
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55Here's the general rule: When you approach a task commonly done
56using a whole range of platforms, think about writing portable
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57code. That way, you don't sacrifice much by way of the implementation
58choices you can avail yourself of, and at the same time you can give
59your users lots of platform choices. On the other hand, when you have to
60take advantage of some unique feature of a particular platform, as is
61often the case with systems programming (whether for Unix, Windows,
62S<Mac OS>, VMS, etc.), consider writing platform-specific code.
63
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64When the code will run on only two or three operating systems, you
65may need to consider only the differences of those particular systems.
66The important thing is to decide where the code will run and to be
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67deliberate in your decision.
68
69The material below is separated into three main sections: main issues of
7ee27b7c 70portability (L<"ISSUES">), platform-specific issues (L<"PLATFORMS">), and
b7df3edc 71built-in perl functions that behave differently on various ports
7ee27b7c 72(L<"FUNCTION IMPLEMENTATIONS">).
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73
74This information should not be considered complete; it includes possibly
b8099c3d 75transient information about idiosyncrasies of some of the ports, almost
b7df3edc 76all of which are in a state of constant evolution. Thus, this material
e41182b5 77should be considered a perpetual work in progress
cc07ed0b 78(C<< <IMG SRC="yellow_sign.gif" ALT="Under Construction"> >>).
e41182b5 79
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80=head1 ISSUES
81
82=head2 Newlines
83
638bc118 84In most operating systems, lines in files are terminated by newlines.
e41182b5 85Just what is used as a newline may vary from OS to OS. Unix
b7df3edc 86traditionally uses C<\012>, one type of DOSish I/O uses C<\015\012>,
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87and S<Mac OS> uses C<\015>.
88
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89Perl uses C<\n> to represent the "logical" newline, where what is
90logical may depend on the platform in use. In MacPerl, C<\n> always
91means C<\015>. In DOSish perls, C<\n> usually means C<\012>, but
92when accessing a file in "text" mode, STDIO translates it to (or
56d7751a 93from) C<\015\012>, depending on whether you're reading or writing.
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94Unix does the same thing on ttys in canonical mode. C<\015\012>
95is commonly referred to as CRLF.
96
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97To trim trailing newlines from text lines use chomp(). With default
98settings that function looks for a trailing C<\n> character and thus
99trims in a portable way.
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100
101When dealing with binary files (or text files in binary mode) be sure
102to explicitly set $/ to the appropriate value for your file format
103before using chomp().
104
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105Because of the "text" mode translation, DOSish perls have limitations
106in using C<seek> and C<tell> on a file accessed in "text" mode.
107Stick to C<seek>-ing to locations you got from C<tell> (and no
108others), and you are usually free to use C<seek> and C<tell> even
109in "text" mode. Using C<seek> or C<tell> or other file operations
110may be non-portable. If you use C<binmode> on a file, however, you
111can usually C<seek> and C<tell> with arbitrary values in safety.
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112
113A common misconception in socket programming is that C<\n> eq C<\012>
0a47030a 114everywhere. When using protocols such as common Internet protocols,
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115C<\012> and C<\015> are called for specifically, and the values of
116the logical C<\n> and C<\r> (carriage return) are not reliable.
117
118 print SOCKET "Hi there, client!\r\n"; # WRONG
119 print SOCKET "Hi there, client!\015\012"; # RIGHT
120
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121However, using C<\015\012> (or C<\cM\cJ>, or C<\x0D\x0A>) can be tedious
122and unsightly, as well as confusing to those maintaining the code. As
6ab3f9cb 123such, the Socket module supplies the Right Thing for those who want it.
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124
125 use Socket qw(:DEFAULT :crlf);
126 print SOCKET "Hi there, client!$CRLF" # RIGHT
127
6ab3f9cb 128When reading from a socket, remember that the default input record
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129separator C<$/> is C<\n>, but robust socket code will recognize as
130either C<\012> or C<\015\012> as end of line:
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131
132 while (<SOCKET>) {
133 # ...
134 }
135
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136Because both CRLF and LF end in LF, the input record separator can
137be set to LF and any CR stripped later. Better to write:
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138
139 use Socket qw(:DEFAULT :crlf);
140 local($/) = LF; # not needed if $/ is already \012
141
142 while (<SOCKET>) {
143 s/$CR?$LF/\n/; # not sure if socket uses LF or CRLF, OK
144 # s/\015?\012/\n/; # same thing
145 }
146
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147This example is preferred over the previous one--even for Unix
148platforms--because now any C<\015>'s (C<\cM>'s) are stripped out
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149(and there was much rejoicing).
150
6ab3f9cb 151Similarly, functions that return text data--such as a function that
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152fetches a web page--should sometimes translate newlines before
153returning the data, if they've not yet been translated to the local
154newline representation. A single line of code will often suffice:
2ee0eb3c 155
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156 $data =~ s/\015?\012/\n/g;
157 return $data;
2ee0eb3c 158
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159Some of this may be confusing. Here's a handy reference to the ASCII CR
160and LF characters. You can print it out and stick it in your wallet.
161
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162 LF eq \012 eq \x0A eq \cJ eq chr(10) eq ASCII 10
163 CR eq \015 eq \x0D eq \cM eq chr(13) eq ASCII 13
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164
165 | Unix | DOS | Mac |
166 ---------------------------
167 \n | LF | LF | CR |
168 \r | CR | CR | LF |
169 \n * | LF | CRLF | CR |
170 \r * | CR | CR | LF |
171 ---------------------------
172 * text-mode STDIO
173
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174The Unix column assumes that you are not accessing a serial line
175(like a tty) in canonical mode. If you are, then CR on input becomes
176"\n", and "\n" on output becomes CRLF.
177
6ab3f9cb 178These are just the most common definitions of C<\n> and C<\r> in Perl.
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179There may well be others. For example, on an EBCDIC implementation
180such as z/OS (OS/390) or OS/400 (using the ILE, the PASE is ASCII-based)
181the above material is similar to "Unix" but the code numbers change:
74555b7a 182
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183 LF eq \025 eq \x15 eq \cU eq chr(21) eq CP-1047 21
184 LF eq \045 eq \x25 eq chr(37) eq CP-0037 37
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185 CR eq \015 eq \x0D eq \cM eq chr(13) eq CP-1047 13
186 CR eq \015 eq \x0D eq \cM eq chr(13) eq CP-0037 13
187
188 | z/OS | OS/400 |
189 ----------------------
190 \n | LF | LF |
191 \r | CR | CR |
192 \n * | LF | LF |
193 \r * | CR | CR |
194 ----------------------
195 * text-mode STDIO
6ab3f9cb 196
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197=head2 Numbers endianness and Width
198
199Different CPUs store integers and floating point numbers in different
200orders (called I<endianness>) and widths (32-bit and 64-bit being the
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201most common today). This affects your programs when they attempt to transfer
202numbers in binary format from one CPU architecture to another,
203usually either "live" via network connection, or by storing the
204numbers to secondary storage such as a disk file or tape.
322422de 205
b7df3edc 206Conflicting storage orders make utter mess out of the numbers. If a
d1e3b762 207little-endian host (Intel, VAX) stores 0x12345678 (305419896 in
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208decimal), a big-endian host (Motorola, Sparc, PA) reads it as
2090x78563412 (2018915346 in decimal). Alpha and MIPS can be either:
210Digital/Compaq used/uses them in little-endian mode; SGI/Cray uses
211them in big-endian mode. To avoid this problem in network (socket)
212connections use the C<pack> and C<unpack> formats C<n> and C<N>, the
213"network" orders. These are guaranteed to be portable.
322422de 214
7a4d2905 215As of perl 5.9.2, you can also use the C<E<gt>> and C<E<lt>> modifiers
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216to force big- or little-endian byte-order. This is useful if you want
217to store signed integers or 64-bit integers, for example.
218
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219You can explore the endianness of your platform by unpacking a
220data structure packed in native format such as:
221
222 print unpack("h*", pack("s2", 1, 2)), "\n";
223 # '10002000' on e.g. Intel x86 or Alpha 21064 in little-endian mode
224 # '00100020' on e.g. Motorola 68040
225
226If you need to distinguish between endian architectures you could use
227either of the variables set like so:
228
229 $is_big_endian = unpack("h*", pack("s", 1)) =~ /01/;
4375e838 230 $is_little_endian = unpack("h*", pack("s", 1)) =~ /^1/;
d1e3b762 231
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232Differing widths can cause truncation even between platforms of equal
233endianness. The platform of shorter width loses the upper parts of the
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234number. There is no good solution for this problem except to avoid
235transferring or storing raw binary numbers.
236
b7df3edc 237One can circumnavigate both these problems in two ways. Either
322422de 238transfer and store numbers always in text format, instead of raw
b7df3edc 239binary, or else consider using modules like Data::Dumper (included in
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240the standard distribution as of Perl 5.005) and Storable (included as
241of perl 5.8). Keeping all data as text significantly simplifies matters.
322422de 242
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243The v-strings are portable only up to v2147483647 (0x7FFFFFFF), that's
244how far EBCDIC, or more precisely UTF-EBCDIC will go.
245
433acd8a 246=head2 Files and Filesystems
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247
248Most platforms these days structure files in a hierarchical fashion.
b7df3edc 249So, it is reasonably safe to assume that all platforms support the
6ab3f9cb 250notion of a "path" to uniquely identify a file on the system. How
b7df3edc 251that path is really written, though, differs considerably.
e41182b5 252
4375e838 253Although similar, file path specifications differ between Unix,
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254Windows, S<Mac OS>, OS/2, VMS, VOS, S<RISC OS>, and probably others.
255Unix, for example, is one of the few OSes that has the elegant idea
256of a single root directory.
322422de 257
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258DOS, OS/2, VMS, VOS, and Windows can work similarly to Unix with C</>
259as path separator, or in their own idiosyncratic ways (such as having
260several root directories and various "unrooted" device files such NIL:
261and LPT:).
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262
263S<Mac OS> uses C<:> as a path separator instead of C</>.
264
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265The filesystem may support neither hard links (C<link>) nor
266symbolic links (C<symlink>, C<readlink>, C<lstat>).
433acd8a 267
6ab3f9cb 268The filesystem may support neither access timestamp nor change
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269timestamp (meaning that about the only portable timestamp is the
270modification timestamp), or one second granularity of any timestamps
271(e.g. the FAT filesystem limits the time granularity to two seconds).
272
74555b7a 273The "inode change timestamp" (the C<-C> filetest) may really be the
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274"creation timestamp" (which it is not in UNIX).
275
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276VOS perl can emulate Unix filenames with C</> as path separator. The
277native pathname characters greater-than, less-than, number-sign, and
278percent-sign are always accepted.
279
6ab3f9cb 280S<RISC OS> perl can emulate Unix filenames with C</> as path
322422de 281separator, or go native and use C<.> for path separator and C<:> to
6ab3f9cb 282signal filesystems and disk names.
e41182b5 283
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284Don't assume UNIX filesystem access semantics: that read, write,
285and execute are all the permissions there are, and even if they exist,
286that their semantics (for example what do r, w, and x mean on
287a directory) are the UNIX ones. The various UNIX/POSIX compatibility
288layers usually try to make interfaces like chmod() work, but sometimes
289there simply is no good mapping.
290
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291If all this is intimidating, have no (well, maybe only a little)
292fear. There are modules that can help. The File::Spec modules
293provide methods to do the Right Thing on whatever platform happens
294to be running the program.
e41182b5 295
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296 use File::Spec::Functions;
297 chdir(updir()); # go up one directory
298 $file = catfile(curdir(), 'temp', 'file.txt');
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299 # on Unix and Win32, './temp/file.txt'
300 # on Mac OS, ':temp:file.txt'
d1e3b762 301 # on VMS, '[.temp]file.txt'
e41182b5 302
b7df3edc 303File::Spec is available in the standard distribution as of version
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3045.004_05. File::Spec::Functions is only in File::Spec 0.7 and later,
305and some versions of perl come with version 0.6. If File::Spec
306is not updated to 0.7 or later, you must use the object-oriented
307interface from File::Spec (or upgrade File::Spec).
e41182b5 308
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309In general, production code should not have file paths hardcoded.
310Making them user-supplied or read from a configuration file is
311better, keeping in mind that file path syntax varies on different
312machines.
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313
314This is especially noticeable in scripts like Makefiles and test suites,
315which often assume C</> as a path separator for subdirectories.
316
b7df3edc 317Also of use is File::Basename from the standard distribution, which
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318splits a pathname into pieces (base filename, full path to directory,
319and file suffix).
320
19799a22 321Even when on a single platform (if you can call Unix a single platform),
b7df3edc 322remember not to count on the existence or the contents of particular
3c075c7d 323system-specific files or directories, like F</etc/passwd>,
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324F</etc/sendmail.conf>, F</etc/resolv.conf>, or even F</tmp/>. For
325example, F</etc/passwd> may exist but not contain the encrypted
326passwords, because the system is using some form of enhanced security.
327Or it may not contain all the accounts, because the system is using NIS.
3c075c7d 328If code does need to rely on such a file, include a description of the
b7df3edc 329file and its format in the code's documentation, then make it easy for
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330the user to override the default location of the file.
331
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332Don't assume a text file will end with a newline. They should,
333but people forget.
e41182b5 334
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335Do not have two files or directories of the same name with different
336case, like F<test.pl> and F<Test.pl>, as many platforms have
337case-insensitive (or at least case-forgiving) filenames. Also, try
338not to have non-word characters (except for C<.>) in the names, and
339keep them to the 8.3 convention, for maximum portability, onerous a
340burden though this may appear.
dd9f0070 341
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342Likewise, when using the AutoSplit module, try to keep your functions to
3438.3 naming and case-insensitive conventions; or, at the least,
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344make it so the resulting files have a unique (case-insensitively)
345first 8 characters.
346
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347Whitespace in filenames is tolerated on most systems, but not all,
348and even on systems where it might be tolerated, some utilities
fe829689 349might become confused by such whitespace.
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351Many systems (DOS, VMS ODS-2) cannot have more than one C<.> in their
352filenames.
433acd8a 353
c47ff5f1 354Don't assume C<< > >> won't be the first character of a filename.
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355Always use C<< < >> explicitly to open a file for reading, or even
356better, use the three-arg version of open, unless you want the user to
357be able to specify a pipe open.
0a47030a 358
fe829689 359 open(FILE, '<', $existing_file) or die $!;
0a47030a 360
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361If filenames might use strange characters, it is safest to open it
362with C<sysopen> instead of C<open>. C<open> is magic and can
c47ff5f1 363translate characters like C<< > >>, C<< < >>, and C<|>, which may
b7df3edc 364be the wrong thing to do. (Sometimes, though, it's the right thing.)
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365Three-arg open can also help protect against this translation in cases
366where it is undesirable.
e41182b5 367
ec481373 368Don't use C<:> as a part of a filename since many systems use that for
8939ba94 369their own semantics (Mac OS Classic for separating pathname components,
ec481373 370many networking schemes and utilities for separating the nodename and
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371the pathname, and so on). For the same reasons, avoid C<@>, C<;> and
372C<|>.
ec481373 373
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374Don't assume that in pathnames you can collapse two leading slashes
375C<//> into one: some networking and clustering filesystems have special
376semantics for that. Let the operating system to sort it out.
377
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378The I<portable filename characters> as defined by ANSI C are
379
380 a b c d e f g h i j k l m n o p q r t u v w x y z
381 A B C D E F G H I J K L M N O P Q R T U V W X Y Z
382 0 1 2 3 4 5 6 7 8 9
383 . _ -
384
08fef530 385and the "-" shouldn't be the first character. If you want to be
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386hypercorrect, stay case-insensitive and within the 8.3 naming
387convention (all the files and directories have to be unique within one
388directory if their names are lowercased and truncated to eight
389characters before the C<.>, if any, and to three characters after the
390C<.>, if any). (And do not use C<.>s in directory names.)
ec481373 391
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392=head2 System Interaction
393
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394Not all platforms provide a command line. These are usually platforms
395that rely primarily on a Graphical User Interface (GUI) for user
396interaction. A program requiring a command line interface might
397not work everywhere. This is probably for the user of the program
398to deal with, so don't stay up late worrying about it.
e41182b5 399
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400Some platforms can't delete or rename files held open by the system,
401this limitation may also apply to changing filesystem metainformation
402like file permissions or owners. Remember to C<close> files when you
403are done with them. Don't C<unlink> or C<rename> an open file. Don't
404C<tie> or C<open> a file already tied or opened; C<untie> or C<close>
405it first.
e41182b5 406
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407Don't open the same file more than once at a time for writing, as some
408operating systems put mandatory locks on such files.
409
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410Don't assume that write/modify permission on a directory gives the
411right to add or delete files/directories in that directory. That is
412filesystem specific: in some filesystems you need write/modify
413permission also (or even just) in the file/directory itself. In some
414filesystems (AFS, DFS) the permission to add/delete directory entries
415is a completely separate permission.
416
417Don't assume that a single C<unlink> completely gets rid of the file:
418some filesystems (most notably the ones in VMS) have versioned
419filesystems, and unlink() removes only the most recent one (it doesn't
420remove all the versions because by default the native tools on those
421platforms remove just the most recent version, too). The portable
422idiom to remove all the versions of a file is
423
94bb614c 424 1 while unlink "file";
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425
426This will terminate if the file is undeleteable for some reason
427(protected, not there, and so on).
428
e41182b5 429Don't count on a specific environment variable existing in C<%ENV>.
0a47030a 430Don't count on C<%ENV> entries being case-sensitive, or even
4a0d0822 431case-preserving. Don't try to clear %ENV by saying C<%ENV = ();>, or,
6be8f7a6 432if you really have to, make it conditional on C<$^O ne 'VMS'> since in
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433VMS the C<%ENV> table is much more than a per-process key-value string
434table.
e41182b5 435
d1e3b762 436Don't count on signals or C<%SIG> for anything.
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437
438Don't count on filename globbing. Use C<opendir>, C<readdir>, and
439C<closedir> instead.
440
b8099c3d 441Don't count on per-program environment variables, or per-program current
dd9f0070 442directories.
b8099c3d 443
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444Don't count on specific values of C<$!>, neither numeric nor
445especially the strings values-- users may switch their locales causing
446error messages to be translated into their languages. If you can
447trust a POSIXish environment, you can portably use the symbols defined
448by the Errno module, like ENOENT. And don't trust on the values of C<$!>
449at all except immediately after a failed system call.
3c075c7d 450
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451=head2 Command names versus file pathnames
452
453Don't assume that the name used to invoke a command or program with
454C<system> or C<exec> can also be used to test for the existence of the
455file that holds the executable code for that command or program.
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456First, many systems have "internal" commands that are built-in to the
457shell or OS and while these commands can be invoked, there is no
458corresponding file. Second, some operating systems (e.g., Cygwin,
459DJGPP, OS/2, and VOS) have required suffixes for executable files;
460these suffixes are generally permitted on the command name but are not
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461required. Thus, a command like "perl" might exist in a file named
462"perl", "perl.exe", or "perl.pm", depending on the operating system.
463The variable "_exe" in the Config module holds the executable suffix,
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464if any. Third, the VMS port carefully sets up $^X and
465$Config{perlpath} so that no further processing is required. This is
466just as well, because the matching regular expression used below would
467then have to deal with a possible trailing version number in the VMS
468file name.
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469
470To convert $^X to a file pathname, taking account of the requirements
471of the various operating system possibilities, say:
7ee27b7c 472
a10d74f3 473 use Config;
a10d74f3 474 $thisperl = $^X;
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475 if ($^O ne 'VMS')
476 {$thisperl .= $Config{_exe} unless $thisperl =~ m/$Config{_exe}$/i;}
a10d74f3
PG
477
478To convert $Config{perlpath} to a file pathname, say:
7ee27b7c 479
a10d74f3 480 use Config;
68fb0eb7
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481 $thisperl = $Config{perlpath};
482 if ($^O ne 'VMS')
483 {$thisperl .= $Config{_exe} unless $thisperl =~ m/$Config{_exe}$/i;}
a10d74f3 484
7137b697
JH
485=head2 Networking
486
487Don't assume that you can reach the public Internet.
488
489Don't assume that there is only one way to get through firewalls
490to the public Internet.
491
932f293e
JH
492Don't assume that you can reach outside world through any other port
493than 80, or some web proxy. ftp is blocked by many firewalls.
494
dbc6a9ce
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495Don't assume that you can send email by connecting to the local SMTP port.
496
7137b697 497Don't assume that you can reach yourself or any node by the name
dbc6a9ce 498'localhost'. The same goes for '127.0.0.1'. You will have to try both.
932f293e 499
86feb2c5
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500Don't assume that the host has only one network card, or that it
501can't bind to many virtual IP addresses.
932f293e
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502
503Don't assume a particular network device name.
7137b697 504
dbc6a9ce 505Don't assume a particular set of ioctl()s will work.
7137b697
JH
506
507Don't assume that you can ping hosts and get replies.
508
dbc6a9ce
JH
509Don't assume that any particular port (service) will respond.
510
7ee27b7c 511Don't assume that Sys::Hostname (or any other API or command)
dbc6a9ce
JH
512returns either a fully qualified hostname or a non-qualified hostname:
513it all depends on how the system had been configured. Also remember
514things like DHCP and NAT-- the hostname you get back might not be very
515useful.
516
932f293e
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517All the above "don't":s may look daunting, and they are -- but the key
518is to degrade gracefully if one cannot reach the particular network
519service one wants. Croaking or hanging do not look very professional.
520
e41182b5
GS
521=head2 Interprocess Communication (IPC)
522
b7df3edc
GS
523In general, don't directly access the system in code meant to be
524portable. That means, no C<system>, C<exec>, C<fork>, C<pipe>,
525C<``>, C<qx//>, C<open> with a C<|>, nor any of the other things
526that makes being a perl hacker worth being.
e41182b5
GS
527
528Commands that launch external processes are generally supported on
b7df3edc
GS
529most platforms (though many of them do not support any type of
530forking). The problem with using them arises from what you invoke
531them on. External tools are often named differently on different
4375e838 532platforms, may not be available in the same location, might accept
b7df3edc
GS
533different arguments, can behave differently, and often present their
534results in a platform-dependent way. Thus, you should seldom depend
535on them to produce consistent results. (Then again, if you're calling
536I<netstat -a>, you probably don't expect it to run on both Unix and CP/M.)
e41182b5 537
b7df3edc 538One especially common bit of Perl code is opening a pipe to B<sendmail>:
e41182b5 539
b7df3edc
GS
540 open(MAIL, '|/usr/lib/sendmail -t')
541 or die "cannot fork sendmail: $!";
e41182b5
GS
542
543This is fine for systems programming when sendmail is known to be
544available. But it is not fine for many non-Unix systems, and even
545some Unix systems that may not have sendmail installed. If a portable
b7df3edc
GS
546solution is needed, see the various distributions on CPAN that deal
547with it. Mail::Mailer and Mail::Send in the MailTools distribution are
548commonly used, and provide several mailing methods, including mail,
549sendmail, and direct SMTP (via Net::SMTP) if a mail transfer agent is
550not available. Mail::Sendmail is a standalone module that provides
551simple, platform-independent mailing.
552
553The Unix System V IPC (C<msg*(), sem*(), shm*()>) is not available
554even on all Unix platforms.
e41182b5 555
a81e5e2e
A
556Do not use either the bare result of C<pack("N", 10, 20, 30, 40)> or
557bare v-strings (such as C<v10.20.30.40>) to represent IPv4 addresses:
558both forms just pack the four bytes into network order. That this
559would be equal to the C language C<in_addr> struct (which is what the
560socket code internally uses) is not guaranteed. To be portable use
561the routines of the Socket extension, such as C<inet_aton()>,
562C<inet_ntoa()>, and C<sockaddr_in()>.
6b2463a0 563
e41182b5 564The rule of thumb for portable code is: Do it all in portable Perl, or
0a47030a
GS
565use a module (that may internally implement it with platform-specific
566code, but expose a common interface).
e41182b5 567
e41182b5
GS
568=head2 External Subroutines (XS)
569
b7df3edc 570XS code can usually be made to work with any platform, but dependent
e41182b5
GS
571libraries, header files, etc., might not be readily available or
572portable, or the XS code itself might be platform-specific, just as Perl
573code might be. If the libraries and headers are portable, then it is
574normally reasonable to make sure the XS code is portable, too.
575
b7df3edc
GS
576A different type of portability issue arises when writing XS code:
577availability of a C compiler on the end-user's system. C brings
578with it its own portability issues, and writing XS code will expose
579you to some of those. Writing purely in Perl is an easier way to
e41182b5
GS
580achieve portability.
581
e41182b5
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582=head2 Standard Modules
583
584In general, the standard modules work across platforms. Notable
6ab3f9cb 585exceptions are the CPAN module (which currently makes connections to external
e41182b5 586programs that may not be available), platform-specific modules (like
6ab3f9cb 587ExtUtils::MM_VMS), and DBM modules.
e41182b5 588
b7df3edc 589There is no one DBM module available on all platforms.
6ab3f9cb
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590SDBM_File and the others are generally available on all Unix and DOSish
591ports, but not in MacPerl, where only NBDM_File and DB_File are
0a47030a 592available.
e41182b5
GS
593
594The good news is that at least some DBM module should be available, and
6ab3f9cb 595AnyDBM_File will use whichever module it can find. Of course, then
b7df3edc
GS
596the code needs to be fairly strict, dropping to the greatest common
597factor (e.g., not exceeding 1K for each record), so that it will
6ab3f9cb 598work with any DBM module. See L<AnyDBM_File> for more details.
e41182b5 599
e41182b5
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600=head2 Time and Date
601
0a47030a 602The system's notion of time of day and calendar date is controlled in
b7df3edc 603widely different ways. Don't assume the timezone is stored in C<$ENV{TZ}>,
0a47030a 604and even if it is, don't assume that you can control the timezone through
c87488a3
HS
605that variable. Don't assume anything about the three-letter timezone
606abbreviations (for example that MST would be the Mountain Standard Time,
607it's been known to stand for Moscow Standard Time). If you need to
608use timezones, express them in some unambiguous format like the
609exact number of minutes offset from UTC, or the POSIX timezone
610format.
e41182b5 611
322422de 612Don't assume that the epoch starts at 00:00:00, January 1, 1970,
c87488a3
HS
613because that is OS- and implementation-specific. It is better to
614store a date in an unambiguous representation. The ISO 8601 standard
615defines YYYY-MM-DD as the date format, or YYYY-MM-DDTHH-MM-SS
616(that's a literal "T" separating the date from the time).
617Please do use the ISO 8601 instead of making us to guess what
618date 02/03/04 might be. ISO 8601 even sorts nicely as-is.
619A text representation (like "1987-12-18") can be easily converted
620into an OS-specific value using a module like Date::Parse.
621An array of values, such as those returned by C<localtime>, can be
622converted to an OS-specific representation using Time::Local.
322422de 623
19799a22
GS
624When calculating specific times, such as for tests in time or date modules,
625it may be appropriate to calculate an offset for the epoch.
b7df3edc 626
19799a22
GS
627 require Time::Local;
628 $offset = Time::Local::timegm(0, 0, 0, 1, 0, 70);
b7df3edc 629
19799a22
GS
630The value for C<$offset> in Unix will be C<0>, but in Mac OS will be
631some large number. C<$offset> can then be added to a Unix time value
632to get what should be the proper value on any system.
322422de 633
bbac04ed
RGS
634On Windows (at least), you shouldn't pass a negative value to C<gmtime> or
635C<localtime>.
636
322422de
GS
637=head2 Character sets and character encoding
638
ec481373
JH
639Assume very little about character sets.
640
641Assume nothing about numerical values (C<ord>, C<chr>) of characters.
642Do not use explicit code point ranges (like \xHH-\xHH); use for
643example symbolic character classes like C<[:print:]>.
644
645Do not assume that the alphabetic characters are encoded contiguously
646(in the numeric sense). There may be gaps.
647
648Do not assume anything about the ordering of the characters.
649The lowercase letters may come before or after the uppercase letters;
b432a672
AL
650the lowercase and uppercase may be interlaced so that both "a" and "A"
651come before "b"; the accented and other international characters may
652be interlaced so that E<auml> comes before "b".
322422de
GS
653
654=head2 Internationalisation
655
b7df3edc
GS
656If you may assume POSIX (a rather large assumption), you may read
657more about the POSIX locale system from L<perllocale>. The locale
658system at least attempts to make things a little bit more portable,
659or at least more convenient and native-friendly for non-English
660users. The system affects character sets and encoding, and date
661and time formatting--amongst other things.
e41182b5 662
c87488a3
HS
663If you really want to be international, you should consider Unicode.
664See L<perluniintro> and L<perlunicode> for more information.
665
11264fdb
JH
666If you want to use non-ASCII bytes (outside the bytes 0x00..0x7f) in
667the "source code" of your code, to be portable you have to be explicit
668about what bytes they are. Someone might for example be using your
669code under a UTF-8 locale, in which case random native bytes might be
670illegal ("Malformed UTF-8 ...") This means that for example embedding
671ISO 8859-1 bytes beyond 0x7f into your strings might cause trouble
672later. If the bytes are native 8-bit bytes, you can use the C<bytes>
673pragma. If the bytes are in a string (regular expression being a
674curious string), you can often also use the C<\xHH> notation instead
675of embedding the bytes as-is. If they are in some particular legacy
676encoding (ether single-byte or something more complicated), you can
677use the C<encoding> pragma. (If you want to write your code in UTF-8,
678you can use either the C<utf8> pragma, or the C<encoding> pragma.)
679The C<bytes> and C<utf8> pragmata are available since Perl 5.6.0, and
680the C<encoding> pragma since Perl 5.8.0.
681
e41182b5
GS
682=head2 System Resources
683
0a47030a
GS
684If your code is destined for systems with severely constrained (or
685missing!) virtual memory systems then you want to be I<especially> mindful
686of avoiding wasteful constructs such as:
e41182b5
GS
687
688 # NOTE: this is no longer "bad" in perl5.005
689 for (0..10000000) {} # bad
690 for (my $x = 0; $x <= 10000000; ++$x) {} # good
691
692 @lines = <VERY_LARGE_FILE>; # bad
693
694 while (<FILE>) {$file .= $_} # sometimes bad
0a47030a 695 $file = join('', <FILE>); # better
e41182b5 696
b7df3edc
GS
697The last two constructs may appear unintuitive to most people. The
698first repeatedly grows a string, whereas the second allocates a
699large chunk of memory in one go. On some systems, the second is
700more efficient that the first.
0a47030a 701
e41182b5
GS
702=head2 Security
703
b7df3edc
GS
704Most multi-user platforms provide basic levels of security, usually
705implemented at the filesystem level. Some, however, do
a1667ba3 706not-- unfortunately. Thus the notion of user id, or "home" directory,
b7df3edc
GS
707or even the state of being logged-in, may be unrecognizable on many
708platforms. If you write programs that are security-conscious, it
709is usually best to know what type of system you will be running
710under so that you can write code explicitly for that platform (or
711class of platforms).
0a47030a 712
a1667ba3
JH
713Don't assume the UNIX filesystem access semantics: the operating
714system or the filesystem may be using some ACL systems, which are
715richer languages than the usual rwx. Even if the rwx exist,
716their semantics might be different.
717
718(From security viewpoint testing for permissions before attempting to
719do something is silly anyway: if one tries this, there is potential
720for race conditions-- someone or something might change the
721permissions between the permissions check and the actual operation.
722Just try the operation.)
723
724Don't assume the UNIX user and group semantics: especially, don't
2edcc0d9 725expect the C<< $< >> and C<< $> >> (or the C<$(> and C<$)>) to work
a1667ba3
JH
726for switching identities (or memberships).
727
728Don't assume set-uid and set-gid semantics. (And even if you do,
729think twice: set-uid and set-gid are a known can of security worms.)
730
e41182b5
GS
731=head2 Style
732
733For those times when it is necessary to have platform-specific code,
734consider keeping the platform-specific code in one place, making porting
6ab3f9cb 735to other platforms easier. Use the Config module and the special
0a47030a
GS
736variable C<$^O> to differentiate platforms, as described in
737L<"PLATFORMS">.
e41182b5 738
b7df3edc
GS
739Be careful in the tests you supply with your module or programs.
740Module code may be fully portable, but its tests might not be. This
741often happens when tests spawn off other processes or call external
742programs to aid in the testing, or when (as noted above) the tests
c87488a3
HS
743assume certain things about the filesystem and paths. Be careful not
744to depend on a specific output style for errors, such as when checking
745C<$!> after a failed system call. Using C<$!> for anything else than
746displaying it as output is doubtful (though see the Errno module for
747testing reasonably portably for error value). Some platforms expect
748a certain output format, and Perl on those platforms may have been
749adjusted accordingly. Most specifically, don't anchor a regex when
750testing an error value.
e41182b5 751
0a47030a 752=head1 CPAN Testers
e41182b5 753
0a47030a
GS
754Modules uploaded to CPAN are tested by a variety of volunteers on
755different platforms. These CPAN testers are notified by mail of each
e41182b5 756new upload, and reply to the list with PASS, FAIL, NA (not applicable to
0a47030a 757this platform), or UNKNOWN (unknown), along with any relevant notations.
e41182b5
GS
758
759The purpose of the testing is twofold: one, to help developers fix any
0a47030a 760problems in their code that crop up because of lack of testing on other
b7df3edc 761platforms; two, to provide users with information about whether
0a47030a 762a given module works on a given platform.
e41182b5 763
7ee27b7c
AT
764Also see:
765
e41182b5
GS
766=over 4
767
7ee27b7c
AT
768=item *
769
770Mailing list: cpan-testers@perl.org
771
772=item *
e41182b5 773
7ee27b7c 774Testing results: http://testers.cpan.org/
e41182b5
GS
775
776=back
777
e41182b5
GS
778=head1 PLATFORMS
779
780As of version 5.002, Perl is built with a C<$^O> variable that
781indicates the operating system it was built on. This was implemented
b7df3edc
GS
782to help speed up code that would otherwise have to C<use Config>
783and use the value of C<$Config{osname}>. Of course, to get more
e41182b5
GS
784detailed information about the system, looking into C<%Config> is
785certainly recommended.
786
b7df3edc
GS
787C<%Config> cannot always be trusted, however, because it was built
788at compile time. If perl was built in one place, then transferred
789elsewhere, some values may be wrong. The values may even have been
790edited after the fact.
6ab3f9cb 791
e41182b5
GS
792=head2 Unix
793
794Perl works on a bewildering variety of Unix and Unix-like platforms (see
795e.g. most of the files in the F<hints/> directory in the source code kit).
796On most of these systems, the value of C<$^O> (hence C<$Config{'osname'}>,
d1e3b762
GS
797too) is determined either by lowercasing and stripping punctuation from the
798first field of the string returned by typing C<uname -a> (or a similar command)
799at the shell prompt or by testing the file system for the presence of
800uniquely named files such as a kernel or header file. Here, for example,
801are a few of the more popular Unix flavors:
e41182b5 802
b7df3edc 803 uname $^O $Config{'archname'}
6ab3f9cb 804 --------------------------------------------
b7df3edc 805 AIX aix aix
6ab3f9cb 806 BSD/OS bsdos i386-bsdos
e1516da7 807 Darwin darwin darwin
6ab3f9cb
GS
808 dgux dgux AViiON-dgux
809 DYNIX/ptx dynixptx i386-dynixptx
b7df3edc 810 FreeBSD freebsd freebsd-i386
d1e3b762 811 Linux linux arm-linux
b7df3edc 812 Linux linux i386-linux
6ab3f9cb
GS
813 Linux linux i586-linux
814 Linux linux ppc-linux
b7df3edc
GS
815 HP-UX hpux PA-RISC1.1
816 IRIX irix irix
b787fad4 817 Mac OS X darwin darwin
d1e3b762
GS
818 MachTen PPC machten powerpc-machten
819 NeXT 3 next next-fat
820 NeXT 4 next OPENSTEP-Mach
6ab3f9cb 821 openbsd openbsd i386-openbsd
b7df3edc 822 OSF1 dec_osf alpha-dec_osf
6ab3f9cb
GS
823 reliantunix-n svr4 RM400-svr4
824 SCO_SV sco_sv i386-sco_sv
825 SINIX-N svr4 RM400-svr4
826 sn4609 unicos CRAY_C90-unicos
827 sn6521 unicosmk t3e-unicosmk
828 sn9617 unicos CRAY_J90-unicos
b7df3edc
GS
829 SunOS solaris sun4-solaris
830 SunOS solaris i86pc-solaris
831 SunOS4 sunos sun4-sunos
e41182b5 832
b7df3edc
GS
833Because the value of C<$Config{archname}> may depend on the
834hardware architecture, it can vary more than the value of C<$^O>.
6ab3f9cb 835
e41182b5
GS
836=head2 DOS and Derivatives
837
b7df3edc 838Perl has long been ported to Intel-style microcomputers running under
e41182b5
GS
839systems like PC-DOS, MS-DOS, OS/2, and most Windows platforms you can
840bring yourself to mention (except for Windows CE, if you count that).
b7df3edc 841Users familiar with I<COMMAND.COM> or I<CMD.EXE> style shells should
e41182b5
GS
842be aware that each of these file specifications may have subtle
843differences:
844
845 $filespec0 = "c:/foo/bar/file.txt";
846 $filespec1 = "c:\\foo\\bar\\file.txt";
847 $filespec2 = 'c:\foo\bar\file.txt';
848 $filespec3 = 'c:\\foo\\bar\\file.txt';
849
b7df3edc
GS
850System calls accept either C</> or C<\> as the path separator.
851However, many command-line utilities of DOS vintage treat C</> as
852the option prefix, so may get confused by filenames containing C</>.
853Aside from calling any external programs, C</> will work just fine,
854and probably better, as it is more consistent with popular usage,
855and avoids the problem of remembering what to backwhack and what
856not to.
e41182b5 857
b7df3edc
GS
858The DOS FAT filesystem can accommodate only "8.3" style filenames. Under
859the "case-insensitive, but case-preserving" HPFS (OS/2) and NTFS (NT)
0a47030a 860filesystems you may have to be careful about case returned with functions
e41182b5
GS
861like C<readdir> or used with functions like C<open> or C<opendir>.
862
b7df3edc
GS
863DOS also treats several filenames as special, such as AUX, PRN,
864NUL, CON, COM1, LPT1, LPT2, etc. Unfortunately, sometimes these
865filenames won't even work if you include an explicit directory
866prefix. It is best to avoid such filenames, if you want your code
867to be portable to DOS and its derivatives. It's hard to know what
868these all are, unfortunately.
e41182b5
GS
869
870Users of these operating systems may also wish to make use of
b7df3edc 871scripts such as I<pl2bat.bat> or I<pl2cmd> to
e41182b5
GS
872put wrappers around your scripts.
873
874Newline (C<\n>) is translated as C<\015\012> by STDIO when reading from
6ab3f9cb
GS
875and writing to files (see L<"Newlines">). C<binmode(FILEHANDLE)>
876will keep C<\n> translated as C<\012> for that filehandle. Since it is a
877no-op on other systems, C<binmode> should be used for cross-platform code
b7df3edc
GS
878that deals with binary data. That's assuming you realize in advance
879that your data is in binary. General-purpose programs should
880often assume nothing about their data.
e41182b5 881
b7df3edc 882The C<$^O> variable and the C<$Config{archname}> values for various
e41182b5
GS
883DOSish perls are as follows:
884
67ac489e
MS
885 OS $^O $Config{archname} ID Version
886 --------------------------------------------------------
887 MS-DOS dos ?
888 PC-DOS dos ?
889 OS/2 os2 ?
890 Windows 3.1 ? ? 0 3 01
891 Windows 95 MSWin32 MSWin32-x86 1 4 00
892 Windows 98 MSWin32 MSWin32-x86 1 4 10
893 Windows ME MSWin32 MSWin32-x86 1 ?
894 Windows NT MSWin32 MSWin32-x86 2 4 xx
895 Windows NT MSWin32 MSWin32-ALPHA 2 4 xx
896 Windows NT MSWin32 MSWin32-ppc 2 4 xx
7ee27b7c
AT
897 Windows 2000 MSWin32 MSWin32-x86 2 5 00
898 Windows XP MSWin32 MSWin32-x86 2 5 01
899 Windows 2003 MSWin32 MSWin32-x86 2 5 02
67ac489e 900 Windows CE MSWin32 ? 3
7ee27b7c 901 Cygwin cygwin cygwin
e41182b5 902
34aaaa84
PP
903The various MSWin32 Perl's can distinguish the OS they are running on
904via the value of the fifth element of the list returned from
905Win32::GetOSVersion(). For example:
906
907 if ($^O eq 'MSWin32') {
908 my @os_version_info = Win32::GetOSVersion();
909 print +('3.1','95','NT')[$os_version_info[4]],"\n";
910 }
911
7939d86b
JH
912There are also Win32::IsWinNT() and Win32::IsWin95(), try C<perldoc Win32>,
913and as of libwin32 0.19 (not part of the core Perl distribution)
914Win32::GetOSName(). The very portable POSIX::uname() will work too:
1d65be3a
JH
915
916 c:\> perl -MPOSIX -we "print join '|', uname"
917 Windows NT|moonru|5.0|Build 2195 (Service Pack 2)|x86
d99f392e 918
e41182b5
GS
919Also see:
920
921=over 4
922
c997b287 923=item *
e41182b5 924
c997b287
GS
925The djgpp environment for DOS, http://www.delorie.com/djgpp/
926and L<perldos>.
e41182b5 927
c997b287 928=item *
e41182b5 929
c997b287
GS
930The EMX environment for DOS, OS/2, etc. emx@iaehv.nl,
931http://www.leo.org/pub/comp/os/os2/leo/gnu/emx+gcc/index.html or
f224927c 932ftp://hobbes.nmsu.edu/pub/os2/dev/emx/ Also L<perlos2>.
e41182b5 933
c997b287 934=item *
d1e3b762 935
c997b287
GS
936Build instructions for Win32 in L<perlwin32>, or under the Cygnus environment
937in L<perlcygwin>.
938
939=item *
940
941The C<Win32::*> modules in L<Win32>.
942
943=item *
944
945The ActiveState Pages, http://www.activestate.com/
946
947=item *
948
949The Cygwin environment for Win32; F<README.cygwin> (installed
47dafe4d 950as L<perlcygwin>), http://www.cygwin.com/
c997b287
GS
951
952=item *
953
954The U/WIN environment for Win32,
cea6626f 955http://www.research.att.com/sw/tools/uwin/
c997b287 956
cea6626f 957=item *
d1e3b762 958
cea6626f 959Build instructions for OS/2, L<perlos2>
d1e3b762 960
e41182b5
GS
961=back
962
dd9f0070 963=head2 S<Mac OS>
e41182b5
GS
964
965Any module requiring XS compilation is right out for most people, because
966MacPerl is built using non-free (and non-cheap!) compilers. Some XS
967modules that can work with MacPerl are built and distributed in binary
6ab3f9cb 968form on CPAN.
e41182b5
GS
969
970Directories are specified as:
971
972 volume:folder:file for absolute pathnames
973 volume:folder: for absolute pathnames
974 :folder:file for relative pathnames
975 :folder: for relative pathnames
976 :file for relative pathnames
977 file for relative pathnames
978
b7df3edc 979Files are stored in the directory in alphabetical order. Filenames are
6ab3f9cb 980limited to 31 characters, and may include any character except for
b7df3edc 981null and C<:>, which is reserved as the path separator.
e41182b5 982
0a47030a 983Instead of C<flock>, see C<FSpSetFLock> and C<FSpRstFLock> in the
6ab3f9cb 984Mac::Files module, or C<chmod(0444, ...)> and C<chmod(0666, ...)>.
e41182b5
GS
985
986In the MacPerl application, you can't run a program from the command line;
987programs that expect C<@ARGV> to be populated can be edited with something
988like the following, which brings up a dialog box asking for the command
989line arguments.
990
991 if (!@ARGV) {
992 @ARGV = split /\s+/, MacPerl::Ask('Arguments?');
993 }
994
b7df3edc 995A MacPerl script saved as a "droplet" will populate C<@ARGV> with the full
e41182b5
GS
996pathnames of the files dropped onto the script.
997
b7df3edc
GS
998Mac users can run programs under a type of command line interface
999under MPW (Macintosh Programmer's Workshop, a free development
1000environment from Apple). MacPerl was first introduced as an MPW
1001tool, and MPW can be used like a shell:
e41182b5
GS
1002
1003 perl myscript.plx some arguments
1004
1005ToolServer is another app from Apple that provides access to MPW tools
0a47030a 1006from MPW and the MacPerl app, which allows MacPerl programs to use
e41182b5
GS
1007C<system>, backticks, and piped C<open>.
1008
1009"S<Mac OS>" is the proper name for the operating system, but the value
1010in C<$^O> is "MacOS". To determine architecture, version, or whether
1011the application or MPW tool version is running, check:
1012
1013 $is_app = $MacPerl::Version =~ /App/;
1014 $is_tool = $MacPerl::Version =~ /MPW/;
1015 ($version) = $MacPerl::Version =~ /^(\S+)/;
1016 $is_ppc = $MacPerl::Architecture eq 'MacPPC';
1017 $is_68k = $MacPerl::Architecture eq 'Mac68K';
1018
b787fad4
JH
1019S<Mac OS X>, based on NeXT's OpenStep OS, runs MacPerl natively, under the
1020"Classic" environment. There is no "Carbon" version of MacPerl to run
1021under the primary Mac OS X environment. S<Mac OS X> and its Open Source
1022version, Darwin, both run Unix perl natively.
6ab3f9cb 1023
e41182b5
GS
1024Also see:
1025
1026=over 4
1027
c997b287
GS
1028=item *
1029
862b5365 1030MacPerl Development, http://dev.macperl.org/ .
c997b287
GS
1031
1032=item *
1033
862b5365 1034The MacPerl Pages, http://www.macperl.com/ .
e41182b5 1035
c997b287 1036=item *
6ab3f9cb 1037
862b5365 1038The MacPerl mailing lists, http://lists.perl.org/ .
e41182b5 1039
7ee27b7c
AT
1040=item *
1041
1042MPW, ftp://ftp.apple.com/developer/Tool_Chest/Core_Mac_OS_Tools/
1043
e41182b5
GS
1044=back
1045
e41182b5
GS
1046=head2 VMS
1047
c997b287 1048Perl on VMS is discussed in L<perlvms> in the perl distribution.
016930a6
JM
1049
1050The official name of VMS as of this writing is OpenVMS.
1051
b7df3edc 1052Perl on VMS can accept either VMS- or Unix-style file
e41182b5
GS
1053specifications as in either of the following:
1054
1055 $ perl -ne "print if /perl_setup/i" SYS$LOGIN:LOGIN.COM
1056 $ perl -ne "print if /perl_setup/i" /sys$login/login.com
1057
1058but not a mixture of both as in:
1059
1060 $ perl -ne "print if /perl_setup/i" sys$login:/login.com
1061 Can't open sys$login:/login.com: file specification syntax error
1062
1063Interacting with Perl from the Digital Command Language (DCL) shell
1064often requires a different set of quotation marks than Unix shells do.
1065For example:
1066
1067 $ perl -e "print ""Hello, world.\n"""
1068 Hello, world.
1069
b7df3edc 1070There are several ways to wrap your perl scripts in DCL F<.COM> files, if
e41182b5
GS
1071you are so inclined. For example:
1072
1073 $ write sys$output "Hello from DCL!"
1074 $ if p1 .eqs. ""
1075 $ then perl -x 'f$environment("PROCEDURE")
1076 $ else perl -x - 'p1 'p2 'p3 'p4 'p5 'p6 'p7 'p8
1077 $ deck/dollars="__END__"
1078 #!/usr/bin/perl
1079
1080 print "Hello from Perl!\n";
1081
1082 __END__
1083 $ endif
1084
1085Do take care with C<$ ASSIGN/nolog/user SYS$COMMAND: SYS$INPUT> if your
c47ff5f1 1086perl-in-DCL script expects to do things like C<< $read = <STDIN>; >>.
e41182b5 1087
016930a6
JM
1088The VMS operating system has two filesystems, known as ODS-2 and ODS-5.
1089
1090For ODS-2, filenames are in the format "name.extension;version". The
1091maximum length for filenames is 39 characters, and the maximum length for
e41182b5
GS
1092extensions is also 39 characters. Version is a number from 1 to
109332767. Valid characters are C</[A-Z0-9$_-]/>.
1094
016930a6
JM
1095The ODS-2 filesystem is case-insensitive and does not preserve case.
1096Perl simulates this by converting all filenames to lowercase internally.
1097
1098For ODS-5, filenames may have almost any character in them and can include
1099Unicode characters. Characters that could be misinterpreted by the DCL
1100shell or file parsing utilities need to be prefixed with the C<^>
1101character, or replaced with hexadecimal characters prefixed with the
1102C<^> character. Such prefixing is only needed with the pathnames are
1103in VMS format in applications. Programs that can accept the UNIX format
1104of pathnames do not need the escape characters. The maximum length for
1105filenames is 255 characters. The ODS-5 file system can handle both
1106a case preserved and a case sensitive mode.
1107
1108ODS-5 is only available on the OpenVMS for 64 bit platforms.
1109
1110Support for the extended file specifications is being done as optional
1111settings to preserve backward compatibility with Perl scripts that
1112assume the previous VMS limitations.
1113
1114In general routines on VMS that get a UNIX format file specification
1115should return it in a UNIX format, and when they get a VMS format
1116specification they should return a VMS format unless they are documented
1117to do a conversion.
1118
1119For routines that generate return a file specification, VMS allows setting
1120if the C library which Perl is built on if it will be returned in VMS
1121format or in UNIX format.
1122
1123With the ODS-2 file system, there is not much difference in syntax of
1124filenames without paths for VMS or UNIX. With the extended character
1125set available with ODS-5 there can be a significant difference.
1126
1127Because of this, existing Perl scripts written for VMS were sometimes
1128treating VMS and UNIX filenames interchangeably. Without the extended
1129character set enabled, this behavior will mostly be maintained for
1130backwards compatibility.
1131
1132When extended characters are enabled with ODS-5, the handling of
1133UNIX formatted file specifications is to that of a UNIX system.
1134
1135VMS file specifications without extensions have a trailing dot. An
1136equivalent UNIX file specification should not show the trailing dot.
1137
1138The result of all of this, is that for VMS, for portable scripts, you
1139can not depend on Perl to present the filenames in lowercase, to be
1140case sensitive, and that the filenames could be returned in either
1141UNIX or VMS format.
1142
1143And if a routine returns a file specification, unless it is intended to
1144convert it, it should return it in the same format as it found it.
1145
1146C<readdir> by default has traditionally returned lowercased filenames.
1147When the ODS-5 support is enabled, it will return the exact case of the
1148filename on the disk.
1149
1150Files without extensions have a trailing period on them, so doing a
1151C<readdir> in the default mode with a file named F<A.;5> will
1152return F<a.> when VMS is (though that file could be opened with
0a47030a 1153C<open(FH, 'A')>).
e41182b5 1154
016930a6
JM
1155With support for extended file specifications and if C<opendir> was
1156given a UNIX format directory, a file named F<A.;5> will return F<a>
1157and optionally in the exact case on the disk. When C<opendir> is given
1158a VMS format directory, then C<readdir> should return F<a.>, and
1159again with the optionally the exact case.
1160
f34d0673 1161RMS had an eight level limit on directory depths from any rooted logical
dd9f0070
CN
1162(allowing 16 levels overall) prior to VMS 7.2. Hence
1163C<PERL_ROOT:[LIB.2.3.4.5.6.7.8]> is a valid directory specification but
1164C<PERL_ROOT:[LIB.2.3.4.5.6.7.8.9]> is not. F<Makefile.PL> authors might
1165have to take this into account, but at least they can refer to the former
f34d0673 1166as C</PERL_ROOT/lib/2/3/4/5/6/7/8/>.
e41182b5 1167
6ab3f9cb 1168The VMS::Filespec module, which gets installed as part of the build
0a47030a
GS
1169process on VMS, is a pure Perl module that can easily be installed on
1170non-VMS platforms and can be helpful for conversions to and from RMS
016930a6
JM
1171native formats. It is also now the only way that you should check to
1172see if VMS is in a case sensitive mode.
e41182b5 1173
5e12dbfa
PP
1174What C<\n> represents depends on the type of file opened. It usually
1175represents C<\012> but it could also be C<\015>, C<\012>, C<\015\012>,
fa11829f 1176C<\000>, C<\040>, or nothing depending on the file organization and
5e12dbfa
PP
1177record format. The VMS::Stdio module provides access to the
1178special fopen() requirements of files with unusual attributes on VMS.
e41182b5
GS
1179
1180TCP/IP stacks are optional on VMS, so socket routines might not be
1181implemented. UDP sockets may not be supported.
1182
016930a6
JM
1183The TCP/IP library support for all current versions of VMS is dynamically
1184loaded if present, so even if the routines are configured, they may
1185return a status indicating that they are not implemented.
1186
e41182b5
GS
1187The value of C<$^O> on OpenVMS is "VMS". To determine the architecture
1188that you are running on without resorting to loading all of C<%Config>
1189you can examine the content of the C<@INC> array like so:
1190
1191 if (grep(/VMS_AXP/, @INC)) {
1192 print "I'm on Alpha!\n";
6ab3f9cb 1193
e41182b5
GS
1194 } elsif (grep(/VMS_VAX/, @INC)) {
1195 print "I'm on VAX!\n";
6ab3f9cb 1196
016930a6
JM
1197 } elsif (grep(/VMS_IA64/, @INC)) {
1198 print "I'm on IA64!\n";
1199
e41182b5
GS
1200 } else {
1201 print "I'm not so sure about where $^O is...\n";
1202 }
1203
016930a6
JM
1204In general, the significant differences should only be if Perl is running
1205on VMS_VAX or one of the 64 bit OpenVMS platforms.
1206
b7df3edc
GS
1207On VMS, perl determines the UTC offset from the C<SYS$TIMEZONE_DIFFERENTIAL>
1208logical name. Although the VMS epoch began at 17-NOV-1858 00:00:00.00,
6ab3f9cb 1209calls to C<localtime> are adjusted to count offsets from
b7df3edc 121001-JAN-1970 00:00:00.00, just like Unix.
6ab3f9cb 1211
e41182b5
GS
1212Also see:
1213
1214=over 4
1215
c997b287
GS
1216=item *
1217
1218F<README.vms> (installed as L<README_vms>), L<perlvms>
1219
1220=item *
1221
1222vmsperl list, majordomo@perl.org
e41182b5 1223
c997b287 1224(Put the words C<subscribe vmsperl> in message body.)
e41182b5 1225
c997b287 1226=item *
e41182b5 1227
c997b287 1228vmsperl on the web, http://www.sidhe.org/vmsperl/index.html
e41182b5
GS
1229
1230=back
1231
495c5fdc
GP
1232=head2 VOS
1233
9a997319
JH
1234Perl on VOS is discussed in F<README.vos> in the perl distribution
1235(installed as L<perlvos>). Perl on VOS can accept either VOS- or
1236Unix-style file specifications as in either of the following:
495c5fdc 1237
cc07ed0b
PG
1238 C<< $ perl -ne "print if /perl_setup/i" >system>notices >>
1239 C<< $ perl -ne "print if /perl_setup/i" /system/notices >>
495c5fdc
GP
1240
1241or even a mixture of both as in:
1242
cc07ed0b 1243 C<< $ perl -ne "print if /perl_setup/i" >system/notices >>
495c5fdc 1244
b7df3edc 1245Even though VOS allows the slash character to appear in object
495c5fdc
GP
1246names, because the VOS port of Perl interprets it as a pathname
1247delimiting character, VOS files, directories, or links whose names
1248contain a slash character cannot be processed. Such files must be
a3dfe201
GS
1249renamed before they can be processed by Perl. Note that VOS limits
1250file names to 32 or fewer characters.
495c5fdc 1251
495c5fdc
GP
1252The value of C<$^O> on VOS is "VOS". To determine the architecture that
1253you are running on without resorting to loading all of C<%Config> you
c997b287 1254can examine the content of the @INC array like so:
495c5fdc 1255
24e8e380 1256 if ($^O =~ /VOS/) {
495c5fdc
GP
1257 print "I'm on a Stratus box!\n";
1258 } else {
1259 print "I'm not on a Stratus box!\n";
1260 die;
1261 }
1262
495c5fdc
GP
1263Also see:
1264
1265=over 4
1266
c997b287 1267=item *
495c5fdc 1268
cc07ed0b 1269F<README.vos> (installed as L<perlvos>)
c997b287
GS
1270
1271=item *
1272
1273The VOS mailing list.
495c5fdc
GP
1274
1275There is no specific mailing list for Perl on VOS. You can post
1276comments to the comp.sys.stratus newsgroup, or subscribe to the general
cc07ed0b 1277Stratus mailing list. Send a letter with "subscribe Info-Stratus" in
495c5fdc
GP
1278the message body to majordomo@list.stratagy.com.
1279
c997b287
GS
1280=item *
1281
cc07ed0b 1282VOS Perl on the web at http://ftp.stratus.com/pub/vos/posix/posix.html
495c5fdc
GP
1283
1284=back
1285
e41182b5
GS
1286=head2 EBCDIC Platforms
1287
1288Recent versions of Perl have been ported to platforms such as OS/400 on
d1e3b762
GS
1289AS/400 minicomputers as well as OS/390, VM/ESA, and BS2000 for S/390
1290Mainframes. Such computers use EBCDIC character sets internally (usually
0cc436d0
GS
1291Character Code Set ID 0037 for OS/400 and either 1047 or POSIX-BC for S/390
1292systems). On the mainframe perl currently works under the "Unix system
1293services for OS/390" (formerly known as OpenEdition), VM/ESA OpenEdition, or
1294the BS200 POSIX-BC system (BS2000 is supported in perl 5.6 and greater).
522b859a
JH
1295See L<perlos390> for details. Note that for OS/400 there is also a port of
1296Perl 5.8.1/5.9.0 or later to the PASE which is ASCII-based (as opposed to
1297ILE which is EBCDIC-based), see L<perlos400>.
e41182b5 1298
7c5ffed3
JH
1299As of R2.5 of USS for OS/390 and Version 2.3 of VM/ESA these Unix
1300sub-systems do not support the C<#!> shebang trick for script invocation.
1301Hence, on OS/390 and VM/ESA perl scripts can be executed with a header
1302similar to the following simple script:
e41182b5
GS
1303
1304 : # use perl
1305 eval 'exec /usr/local/bin/perl -S $0 ${1+"$@"}'
1306 if 0;
1307 #!/usr/local/bin/perl # just a comment really
1308
1309 print "Hello from perl!\n";
1310
d1e3b762
GS
1311OS/390 will support the C<#!> shebang trick in release 2.8 and beyond.
1312Calls to C<system> and backticks can use POSIX shell syntax on all
1313S/390 systems.
1314
b7df3edc 1315On the AS/400, if PERL5 is in your library list, you may need
6ab3f9cb
GS
1316to wrap your perl scripts in a CL procedure to invoke them like so:
1317
1318 BEGIN
1319 CALL PGM(PERL5/PERL) PARM('/QOpenSys/hello.pl')
1320 ENDPGM
1321
1322This will invoke the perl script F<hello.pl> in the root of the
1323QOpenSys file system. On the AS/400 calls to C<system> or backticks
1324must use CL syntax.
1325
e41182b5 1326On these platforms, bear in mind that the EBCDIC character set may have
0a47030a
GS
1327an effect on what happens with some perl functions (such as C<chr>,
1328C<pack>, C<print>, C<printf>, C<ord>, C<sort>, C<sprintf>, C<unpack>), as
1329well as bit-fiddling with ASCII constants using operators like C<^>, C<&>
1330and C<|>, not to mention dealing with socket interfaces to ASCII computers
6ab3f9cb 1331(see L<"Newlines">).
e41182b5 1332
b7df3edc
GS
1333Fortunately, most web servers for the mainframe will correctly
1334translate the C<\n> in the following statement to its ASCII equivalent
1335(C<\r> is the same under both Unix and OS/390 & VM/ESA):
e41182b5
GS
1336
1337 print "Content-type: text/html\r\n\r\n";
1338
d1e3b762 1339The values of C<$^O> on some of these platforms includes:
e41182b5 1340
d1e3b762
GS
1341 uname $^O $Config{'archname'}
1342 --------------------------------------------
1343 OS/390 os390 os390
1344 OS400 os400 os400
1345 POSIX-BC posix-bc BS2000-posix-bc
1346 VM/ESA vmesa vmesa
3c075c7d 1347
e41182b5
GS
1348Some simple tricks for determining if you are running on an EBCDIC
1349platform could include any of the following (perhaps all):
1350
1351 if ("\t" eq "\05") { print "EBCDIC may be spoken here!\n"; }
1352
1353 if (ord('A') == 193) { print "EBCDIC may be spoken here!\n"; }
1354
1355 if (chr(169) eq 'z') { print "EBCDIC may be spoken here!\n"; }
1356
b7df3edc 1357One thing you may not want to rely on is the EBCDIC encoding
0a47030a
GS
1358of punctuation characters since these may differ from code page to code
1359page (and once your module or script is rumoured to work with EBCDIC,
1360folks will want it to work with all EBCDIC character sets).
e41182b5
GS
1361
1362Also see:
1363
1364=over 4
1365
c997b287
GS
1366=item *
1367
dc5c060f 1368L<perlos390>, F<README.os390>, F<perlbs2000>, F<README.vmesa>,
bb462878 1369L<perlebcdic>.
c997b287
GS
1370
1371=item *
e41182b5
GS
1372
1373The perl-mvs@perl.org list is for discussion of porting issues as well as
1374general usage issues for all EBCDIC Perls. Send a message body of
1375"subscribe perl-mvs" to majordomo@perl.org.
1376
7ee27b7c 1377=item *
c997b287
GS
1378
1379AS/400 Perl information at
b1866b2d 1380http://as400.rochester.ibm.com/
d1e3b762 1381as well as on CPAN in the F<ports/> directory.
e41182b5
GS
1382
1383=back
1384
b8099c3d
CN
1385=head2 Acorn RISC OS
1386
b7df3edc
GS
1387Because Acorns use ASCII with newlines (C<\n>) in text files as C<\012> like
1388Unix, and because Unix filename emulation is turned on by default,
1389most simple scripts will probably work "out of the box". The native
6ab3f9cb 1390filesystem is modular, and individual filesystems are free to be
0a47030a 1391case-sensitive or insensitive, and are usually case-preserving. Some
b7df3edc 1392native filesystems have name length limits, which file and directory
6ab3f9cb
GS
1393names are silently truncated to fit. Scripts should be aware that the
1394standard filesystem currently has a name length limit of B<10>
1395characters, with up to 77 items in a directory, but other filesystems
0a47030a 1396may not impose such limitations.
b8099c3d
CN
1397
1398Native filenames are of the form
1399
6ab3f9cb 1400 Filesystem#Special_Field::DiskName.$.Directory.Directory.File
dd9f0070 1401
b8099c3d
CN
1402where
1403
1404 Special_Field is not usually present, but may contain . and $ .
1405 Filesystem =~ m|[A-Za-z0-9_]|
1406 DsicName =~ m|[A-Za-z0-9_/]|
1407 $ represents the root directory
1408 . is the path separator
1409 @ is the current directory (per filesystem but machine global)
1410 ^ is the parent directory
1411 Directory and File =~ m|[^\0- "\.\$\%\&:\@\\^\|\177]+|
1412
1413The default filename translation is roughly C<tr|/.|./|;>
1414
6ab3f9cb 1415Note that C<"ADFS::HardDisk.$.File" ne 'ADFS::HardDisk.$.File'> and that
0a47030a
GS
1416the second stage of C<$> interpolation in regular expressions will fall
1417foul of the C<$.> if scripts are not careful.
1418
1419Logical paths specified by system variables containing comma-separated
b7df3edc 1420search lists are also allowed; hence C<System:Modules> is a valid
0a47030a 1421filename, and the filesystem will prefix C<Modules> with each section of
6ab3f9cb 1422C<System$Path> until a name is made that points to an object on disk.
b7df3edc 1423Writing to a new file C<System:Modules> would be allowed only if
0a47030a
GS
1424C<System$Path> contains a single item list. The filesystem will also
1425expand system variables in filenames if enclosed in angle brackets, so
c47ff5f1 1426C<< <System$Dir>.Modules >> would look for the file
0a47030a 1427S<C<$ENV{'System$Dir'} . 'Modules'>>. The obvious implication of this is
c47ff5f1 1428that B<fully qualified filenames can start with C<< <> >>> and should
0a47030a 1429be protected when C<open> is used for input.
b8099c3d
CN
1430
1431Because C<.> was in use as a directory separator and filenames could not
1432be assumed to be unique after 10 characters, Acorn implemented the C
1433compiler to strip the trailing C<.c> C<.h> C<.s> and C<.o> suffix from
1434filenames specified in source code and store the respective files in
b7df3edc 1435subdirectories named after the suffix. Hence files are translated:
b8099c3d
CN
1436
1437 foo.h h.foo
1438 C:foo.h C:h.foo (logical path variable)
1439 sys/os.h sys.h.os (C compiler groks Unix-speak)
1440 10charname.c c.10charname
1441 10charname.o o.10charname
1442 11charname_.c c.11charname (assuming filesystem truncates at 10)
1443
1444The Unix emulation library's translation of filenames to native assumes
b7df3edc
GS
1445that this sort of translation is required, and it allows a user-defined list
1446of known suffixes that it will transpose in this fashion. This may
1447seem transparent, but consider that with these rules C<foo/bar/baz.h>
0a47030a
GS
1448and C<foo/bar/h/baz> both map to C<foo.bar.h.baz>, and that C<readdir> and
1449C<glob> cannot and do not attempt to emulate the reverse mapping. Other
6ab3f9cb 1450C<.>'s in filenames are translated to C</>.
0a47030a 1451
b7df3edc 1452As implied above, the environment accessed through C<%ENV> is global, and
0a47030a 1453the convention is that program specific environment variables are of the
6ab3f9cb
GS
1454form C<Program$Name>. Each filesystem maintains a current directory,
1455and the current filesystem's current directory is the B<global> current
b7df3edc
GS
1456directory. Consequently, sociable programs don't change the current
1457directory but rely on full pathnames, and programs (and Makefiles) cannot
0a47030a
GS
1458assume that they can spawn a child process which can change the current
1459directory without affecting its parent (and everyone else for that
1460matter).
1461
b7df3edc
GS
1462Because native operating system filehandles are global and are currently
1463allocated down from 255, with 0 being a reserved value, the Unix emulation
0a47030a
GS
1464library emulates Unix filehandles. Consequently, you can't rely on
1465passing C<STDIN>, C<STDOUT>, or C<STDERR> to your children.
1466
1467The desire of users to express filenames of the form
c47ff5f1 1468C<< <Foo$Dir>.Bar >> on the command line unquoted causes problems,
0a47030a 1469too: C<``> command output capture has to perform a guessing game. It
c47ff5f1 1470assumes that a string C<< <[^<>]+\$[^<>]> >> is a
0a47030a 1471reference to an environment variable, whereas anything else involving
c47ff5f1 1472C<< < >> or C<< > >> is redirection, and generally manages to be 99%
0a47030a
GS
1473right. Of course, the problem remains that scripts cannot rely on any
1474Unix tools being available, or that any tools found have Unix-like command
1475line arguments.
1476
b7df3edc
GS
1477Extensions and XS are, in theory, buildable by anyone using free
1478tools. In practice, many don't, as users of the Acorn platform are
1479used to binary distributions. MakeMaker does run, but no available
1480make currently copes with MakeMaker's makefiles; even if and when
1481this should be fixed, the lack of a Unix-like shell will cause
1482problems with makefile rules, especially lines of the form C<cd
1483sdbm && make all>, and anything using quoting.
b8099c3d
CN
1484
1485"S<RISC OS>" is the proper name for the operating system, but the value
1486in C<$^O> is "riscos" (because we don't like shouting).
1487
e41182b5
GS
1488=head2 Other perls
1489
b7df3edc
GS
1490Perl has been ported to many platforms that do not fit into any of
1491the categories listed above. Some, such as AmigaOS, Atari MiNT,
1492BeOS, HP MPE/iX, QNX, Plan 9, and VOS, have been well-integrated
1493into the standard Perl source code kit. You may need to see the
1494F<ports/> directory on CPAN for information, and possibly binaries,
1495for the likes of: aos, Atari ST, lynxos, riscos, Novell Netware,
1496Tandem Guardian, I<etc.> (Yes, we know that some of these OSes may
1497fall under the Unix category, but we are not a standards body.)
e41182b5 1498
d1e3b762
GS
1499Some approximate operating system names and their C<$^O> values
1500in the "OTHER" category include:
1501
1502 OS $^O $Config{'archname'}
1503 ------------------------------------------
1504 Amiga DOS amigaos m68k-amigos
cec2c193 1505 BeOS beos
d1e3b762
GS
1506 MPE/iX mpeix PA-RISC1.1
1507
e41182b5
GS
1508See also:
1509
1510=over 4
1511
c997b287
GS
1512=item *
1513
1514Amiga, F<README.amiga> (installed as L<perlamiga>).
1515
1516=item *
d1e3b762 1517
c997b287
GS
1518Atari, F<README.mint> and Guido Flohr's web page
1519http://stud.uni-sb.de/~gufl0000/
e41182b5 1520
c997b287 1521=item *
d1e3b762 1522
c997b287 1523Be OS, F<README.beos>
e41182b5 1524
c997b287
GS
1525=item *
1526
1527HP 300 MPE/iX, F<README.mpeix> and Mark Bixby's web page
34aaaa84 1528http://www.bixby.org/mark/perlix.html
c997b287
GS
1529
1530=item *
e41182b5 1531
6ab3f9cb 1532A free perl5-based PERL.NLM for Novell Netware is available in
c997b287 1533precompiled binary and source code form from http://www.novell.com/
6ab3f9cb 1534as well as from CPAN.
e41182b5 1535
13a2d996 1536=item *
c997b287 1537
e6f03d26 1538S<Plan 9>, F<README.plan9>
d1e3b762 1539
e41182b5
GS
1540=back
1541
e41182b5
GS
1542=head1 FUNCTION IMPLEMENTATIONS
1543
b7df3edc
GS
1544Listed below are functions that are either completely unimplemented
1545or else have been implemented differently on various platforms.
1546Following each description will be, in parentheses, a list of
1547platforms that the description applies to.
e41182b5 1548
b7df3edc
GS
1549The list may well be incomplete, or even wrong in some places. When
1550in doubt, consult the platform-specific README files in the Perl
1551source distribution, and any other documentation resources accompanying
1552a given port.
e41182b5 1553
0a47030a 1554Be aware, moreover, that even among Unix-ish systems there are variations.
e41182b5 1555
b7df3edc
GS
1556For many functions, you can also query C<%Config>, exported by
1557default from the Config module. For example, to check whether the
1558platform has the C<lstat> call, check C<$Config{d_lstat}>. See
1559L<Config> for a full description of available variables.
e41182b5
GS
1560
1561=head2 Alphabetical Listing of Perl Functions
1562
1563=over 8
1564
e41182b5
GS
1565=item -X
1566
b7df3edc 1567C<-r>, C<-w>, and C<-x> have a limited meaning only; directories
e41182b5 1568and applications are executable, and there are no uid/gid
b7df3edc 1569considerations. C<-o> is not supported. (S<Mac OS>)
e41182b5 1570
b7df3edc
GS
1571C<-r>, C<-w>, C<-x>, and C<-o> tell whether the file is accessible,
1572which may not reflect UIC-based file protections. (VMS)
e41182b5 1573
b8099c3d
CN
1574C<-s> returns the size of the data fork, not the total size of data fork
1575plus resource fork. (S<Mac OS>).
1576
1577C<-s> by name on an open file will return the space reserved on disk,
1578rather than the current extent. C<-s> on an open filehandle returns the
b7df3edc 1579current size. (S<RISC OS>)
b8099c3d 1580
e41182b5 1581C<-R>, C<-W>, C<-X>, C<-O> are indistinguishable from C<-r>, C<-w>,
b8099c3d 1582C<-x>, C<-o>. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5
GS
1583
1584C<-b>, C<-c>, C<-k>, C<-g>, C<-p>, C<-u>, C<-A> are not implemented.
1585(S<Mac OS>)
1586
1587C<-g>, C<-k>, C<-l>, C<-p>, C<-u>, C<-A> are not particularly meaningful.
b8099c3d 1588(Win32, VMS, S<RISC OS>)
e41182b5
GS
1589
1590C<-d> is true if passed a device spec without an explicit directory.
1591(VMS)
1592
1593C<-T> and C<-B> are implemented, but might misclassify Mac text files
0a47030a 1594with foreign characters; this is the case will all platforms, but may
b7df3edc 1595affect S<Mac OS> often. (S<Mac OS>)
e41182b5
GS
1596
1597C<-x> (or C<-X>) determine if a file ends in one of the executable
b7df3edc 1598suffixes. C<-S> is meaningless. (Win32)
e41182b5 1599
b8099c3d
CN
1600C<-x> (or C<-X>) determine if a file has an executable file type.
1601(S<RISC OS>)
1602
47cd99a4 1603=item atan2
519bc777
RGS
1604
1605Due to issues with various CPUs, math libraries, compilers, and standards,
1606results for C<atan2()> may vary depending on any combination of the above.
1607Perl attempts to conform to the Open Group/IEEE standards for the results
1608returned from C<atan2()>, but cannot force the issue if the system Perl is
1609run on does not allow it. (Tru64, HP-UX 10.20)
1610
1611The current version of the standards for C<atan2()> is available at
1612L<http://www.opengroup.org/onlinepubs/009695399/functions/atan2.html>.
1613
47cd99a4 1614=item binmode
e41182b5 1615
b7df3edc 1616Meaningless. (S<Mac OS>, S<RISC OS>)
e41182b5
GS
1617
1618Reopens file and restores pointer; if function fails, underlying
1619filehandle may be closed, or pointer may be in a different position.
1620(VMS)
1621
1622The value returned by C<tell> may be affected after the call, and
1623the filehandle may be flushed. (Win32)
1624
47cd99a4 1625=item chmod
e41182b5 1626
b7df3edc 1627Only limited meaning. Disabling/enabling write permission is mapped to
e41182b5
GS
1628locking/unlocking the file. (S<Mac OS>)
1629
1630Only good for changing "owner" read-write access, "group", and "other"
1631bits are meaningless. (Win32)
1632
b8099c3d
CN
1633Only good for changing "owner" and "other" read-write access. (S<RISC OS>)
1634
495c5fdc
GP
1635Access permissions are mapped onto VOS access-control list changes. (VOS)
1636
4e51f8e4 1637The actual permissions set depend on the value of the C<CYGWIN>
789f0d36 1638in the SYSTEM environment settings. (Cygwin)
4e51f8e4 1639
47cd99a4 1640=item chown
e41182b5 1641
3fd80bd6 1642Not implemented. (S<Mac OS>, Win32, S<Plan 9>, S<RISC OS>)
e41182b5
GS
1643
1644Does nothing, but won't fail. (Win32)
1645
3fd80bd6
PG
1646A little funky, because VOS's notion of ownership is a little funky (VOS).
1647
e41182b5
GS
1648=item chroot
1649
e6f03d26 1650Not implemented. (S<Mac OS>, Win32, VMS, S<Plan 9>, S<RISC OS>, VOS, VM/ESA)
e41182b5 1651
47cd99a4 1652=item crypt
e41182b5
GS
1653
1654May not be available if library or source was not provided when building
b8099c3d 1655perl. (Win32)
e41182b5 1656
47cd99a4 1657=item dbmclose
e41182b5 1658
e6f03d26 1659Not implemented. (VMS, S<Plan 9>, VOS)
e41182b5 1660
47cd99a4 1661=item dbmopen
e41182b5 1662
e6f03d26 1663Not implemented. (VMS, S<Plan 9>, VOS)
e41182b5 1664
47cd99a4 1665=item dump
e41182b5 1666
b8099c3d 1667Not useful. (S<Mac OS>, S<RISC OS>)
e41182b5 1668
84d78eb7 1669Not supported. (Cygwin, Win32)
e41182b5 1670
b8099c3d 1671Invokes VMS debugger. (VMS)
e41182b5 1672
47cd99a4 1673=item exec
e41182b5
GS
1674
1675Not implemented. (S<Mac OS>)
1676
7c5ffed3 1677Implemented via Spawn. (VM/ESA)
3c075c7d 1678
0f897271
GS
1679Does not automatically flush output handles on some platforms.
1680(SunOS, Solaris, HP-UX)
1681
fe12c0e8
MS
1682=item exit
1683
1684Emulates UNIX exit() (which considers C<exit 1> to indicate an error) by
1685mapping the C<1> to SS$_ABORT (C<44>). This behavior may be overridden
1686with the pragma C<use vmsish 'exit'>. As with the CRTL's exit()
1687function, C<exit 0> is also mapped to an exit status of SS$_NORMAL
1688(C<1>); this mapping cannot be overridden. Any other argument to exit()
016930a6
JM
1689is used directly as Perl's exit status. On VMS, unless the future
1690POSIX_EXIT mode is enabled, the exit code should always be a valid
1691VMS exit code and not a generic number. When the POSIX_EXIT mode is
1692enabled, a generic number will be encoded in a method compatible with
1693the C library _POSIX_EXIT macro so that it can be decoded by other
1694programs, particularly ones written in C, like the GNV package. (VMS)
fe12c0e8 1695
47cd99a4 1696=item fcntl
e41182b5 1697
016930a6
JM
1698Not implemented. (Win32)
1699Some functions available based on the version of VMS. (VMS)
e41182b5 1700
47cd99a4 1701=item flock
e41182b5 1702
495c5fdc 1703Not implemented (S<Mac OS>, VMS, S<RISC OS>, VOS).
e41182b5
GS
1704
1705Available only on Windows NT (not on Windows 95). (Win32)
1706
1707=item fork
1708
3fd80bd6 1709Not implemented. (S<Mac OS>, AmigaOS, S<RISC OS>, VM/ESA, VMS)
0f897271
GS
1710
1711Emulated using multiple interpreters. See L<perlfork>. (Win32)
1712
1713Does not automatically flush output handles on some platforms.
1714(SunOS, Solaris, HP-UX)
e41182b5
GS
1715
1716=item getlogin
1717
b8099c3d 1718Not implemented. (S<Mac OS>, S<RISC OS>)
e41182b5 1719
47cd99a4 1720=item getpgrp
e41182b5 1721
3fd80bd6 1722Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5
GS
1723
1724=item getppid
1725
41cbbefa 1726Not implemented. (S<Mac OS>, Win32, S<RISC OS>)
e41182b5 1727
47cd99a4 1728=item getpriority
e41182b5 1729
7c5ffed3 1730Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
e41182b5 1731
47cd99a4 1732=item getpwnam
e41182b5
GS
1733
1734Not implemented. (S<Mac OS>, Win32)
1735
b8099c3d
CN
1736Not useful. (S<RISC OS>)
1737
47cd99a4 1738=item getgrnam
e41182b5 1739
b8099c3d 1740Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5 1741
47cd99a4 1742=item getnetbyname
e41182b5 1743
e6f03d26 1744Not implemented. (S<Mac OS>, Win32, S<Plan 9>)
e41182b5 1745
47cd99a4 1746=item getpwuid
e41182b5
GS
1747
1748Not implemented. (S<Mac OS>, Win32)
1749
b8099c3d
CN
1750Not useful. (S<RISC OS>)
1751
47cd99a4 1752=item getgrgid
e41182b5 1753
b8099c3d 1754Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>)
e41182b5 1755
47cd99a4 1756=item getnetbyaddr
e41182b5 1757
e6f03d26 1758Not implemented. (S<Mac OS>, Win32, S<Plan 9>)
e41182b5 1759
47cd99a4 1760=item getprotobynumber
e41182b5
GS
1761
1762Not implemented. (S<Mac OS>)
1763
47cd99a4 1764=item getservbyport
e41182b5
GS
1765
1766Not implemented. (S<Mac OS>)
1767
1768=item getpwent
1769
7c5ffed3 1770Not implemented. (S<Mac OS>, Win32, VM/ESA)
e41182b5
GS
1771
1772=item getgrent
1773
7c5ffed3 1774Not implemented. (S<Mac OS>, Win32, VMS, VM/ESA)
e41182b5 1775
ef5a6dd7
JH
1776=item gethostbyname
1777
1778C<gethostbyname('localhost')> does not work everywhere: you may have
1779to use C<gethostbyname('127.0.0.1')>. (S<Mac OS>, S<Irix 5>)
1780
e41182b5
GS
1781=item gethostent
1782
1783Not implemented. (S<Mac OS>, Win32)
1784
1785=item getnetent
1786
e6f03d26 1787Not implemented. (S<Mac OS>, Win32, S<Plan 9>)
e41182b5
GS
1788
1789=item getprotoent
1790
e6f03d26 1791Not implemented. (S<Mac OS>, Win32, S<Plan 9>)
e41182b5
GS
1792
1793=item getservent
1794
e6f03d26 1795Not implemented. (Win32, S<Plan 9>)
e41182b5 1796
47cd99a4 1797=item sethostent
e41182b5 1798
e6f03d26 1799Not implemented. (S<Mac OS>, Win32, S<Plan 9>, S<RISC OS>)
e41182b5 1800
47cd99a4 1801=item setnetent
e41182b5 1802
e6f03d26 1803Not implemented. (S<Mac OS>, Win32, S<Plan 9>, S<RISC OS>)
e41182b5 1804
47cd99a4 1805=item setprotoent
e41182b5 1806
e6f03d26 1807Not implemented. (S<Mac OS>, Win32, S<Plan 9>, S<RISC OS>)
e41182b5 1808
47cd99a4 1809=item setservent
e41182b5 1810
e6f03d26 1811Not implemented. (S<Plan 9>, Win32, S<RISC OS>)
e41182b5
GS
1812
1813=item endpwent
1814
a3dfe201 1815Not implemented. (S<Mac OS>, MPE/iX, VM/ESA, Win32)
e41182b5
GS
1816
1817=item endgrent
1818
a3dfe201 1819Not implemented. (S<Mac OS>, MPE/iX, S<RISC OS>, VM/ESA, VMS, Win32)
e41182b5
GS
1820
1821=item endhostent
1822
1823Not implemented. (S<Mac OS>, Win32)
1824
1825=item endnetent
1826
e6f03d26 1827Not implemented. (S<Mac OS>, Win32, S<Plan 9>)
e41182b5
GS
1828
1829=item endprotoent
1830
e6f03d26 1831Not implemented. (S<Mac OS>, Win32, S<Plan 9>)
e41182b5
GS
1832
1833=item endservent
1834
e6f03d26 1835Not implemented. (S<Plan 9>, Win32)
e41182b5
GS
1836
1837=item getsockopt SOCKET,LEVEL,OPTNAME
1838
e6f03d26 1839Not implemented. (S<Plan 9>)
e41182b5 1840
e41182b5
GS
1841=item glob
1842
63f87e49
GS
1843This operator is implemented via the File::Glob extension on most
1844platforms. See L<File::Glob> for portability information.
b8099c3d 1845
62aa5637
MS
1846=item gmtime
1847
1848Same portability caveats as L<localtime>.
1849
e41182b5
GS
1850=item ioctl FILEHANDLE,FUNCTION,SCALAR
1851
1852Not implemented. (VMS)
1853
1854Available only for socket handles, and it does what the ioctlsocket() call
1855in the Winsock API does. (Win32)
1856
b8099c3d
CN
1857Available only for socket handles. (S<RISC OS>)
1858
47cd99a4 1859=item kill
e41182b5 1860
862b5365
JH
1861C<kill(0, LIST)> is implemented for the sake of taint checking;
1862use with other signals is unimplemented. (S<Mac OS>)
1863
1864Not implemented, hence not useful for taint checking. (S<RISC OS>)
e41182b5 1865
63f87e49
GS
1866C<kill()> doesn't have the semantics of C<raise()>, i.e. it doesn't send
1867a signal to the identified process like it does on Unix platforms.
1868Instead C<kill($sig, $pid)> terminates the process identified by $pid,
1869and makes it exit immediately with exit status $sig. As in Unix, if
1870$sig is 0 and the specified process exists, it returns true without
1871actually terminating it. (Win32)
e41182b5 1872
016930a6
JM
1873Is not supported for process identification number of 0 or negative
1874numbers. (VMS)
1875
47cd99a4 1876=item link
e41182b5 1877
016930a6 1878Not implemented. (S<Mac OS>, MPE/iX, S<RISC OS>)
e41182b5 1879
433acd8a
JH
1880Link count not updated because hard links are not quite that hard
1881(They are sort of half-way between hard and soft links). (AmigaOS)
1882
a3dfe201
GS
1883Hard links are implemented on Win32 (Windows NT and Windows 2000)
1884under NTFS only.
1885
016930a6
JM
1886Available on 64 bit OpenVMS 8.2 and later. (VMS)
1887
62aa5637
MS
1888=item localtime
1889
1890Because Perl currently relies on the native standard C localtime()
1891function, it is only safe to use times between 0 and (2**31)-1. Times
1892outside this range may result in unexpected behavior depending on your
1893operating system's implementation of localtime().
1894
e41182b5
GS
1895=item lstat
1896
016930a6 1897Not implemented. (S<RISC OS>)
e41182b5 1898
63f87e49 1899Return values (especially for device and inode) may be bogus. (Win32)
e41182b5 1900
47cd99a4 1901=item msgctl
e41182b5 1902
47cd99a4 1903=item msgget
e41182b5 1904
47cd99a4 1905=item msgsnd
e41182b5 1906
47cd99a4 1907=item msgrcv
e41182b5 1908
e6f03d26 1909Not implemented. (S<Mac OS>, Win32, VMS, S<Plan 9>, S<RISC OS>, VOS)
e41182b5 1910
47cd99a4 1911=item open
e41182b5 1912
b7df3edc 1913The C<|> variants are supported only if ToolServer is installed.
e41182b5
GS
1914(S<Mac OS>)
1915
c47ff5f1 1916open to C<|-> and C<-|> are unsupported. (S<Mac OS>, Win32, S<RISC OS>)
e41182b5 1917
0f897271
GS
1918Opening a process does not automatically flush output handles on some
1919platforms. (SunOS, Solaris, HP-UX)
1920
47cd99a4 1921=item pipe
e41182b5 1922
433acd8a
JH
1923Very limited functionality. (MiNT)
1924
e41182b5
GS
1925=item readlink
1926
b8099c3d 1927Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5 1928
47cd99a4 1929=item rename
c9b2b9d4
SS
1930
1931Can't move directories between directories on different logical volumes. (Win32)
1932
47cd99a4 1933=item select
e41182b5 1934
689c5c24 1935Only implemented on sockets. (Win32, VMS)
e41182b5 1936
b8099c3d
CN
1937Only reliable on sockets. (S<RISC OS>)
1938
76e05f0b 1939Note that the C<select FILEHANDLE> form is generally portable.
63f87e49 1940
47cd99a4 1941=item semctl
e41182b5 1942
47cd99a4 1943=item semget
e41182b5 1944
47cd99a4 1945=item semop
e41182b5 1946
495c5fdc 1947Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5 1948
a3dfe201
GS
1949=item setgrent
1950
3fd80bd6 1951Not implemented. (S<Mac OS>, MPE/iX, VMS, Win32, S<RISC OS>, VOS)
a3dfe201 1952
47cd99a4 1953=item setpgrp
e41182b5 1954
495c5fdc 1955Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5 1956
47cd99a4 1957=item setpriority
e41182b5 1958
495c5fdc 1959Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5 1960
a3dfe201
GS
1961=item setpwent
1962
3fd80bd6 1963Not implemented. (S<Mac OS>, MPE/iX, Win32, S<RISC OS>, VOS)
a3dfe201 1964
47cd99a4 1965=item setsockopt
e41182b5 1966
e6f03d26 1967Not implemented. (S<Plan 9>)
e41182b5 1968
47cd99a4 1969=item shmctl
e41182b5 1970
47cd99a4 1971=item shmget
e41182b5 1972
47cd99a4 1973=item shmread
e41182b5 1974
47cd99a4 1975=item shmwrite
e41182b5 1976
495c5fdc 1977Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS)
e41182b5 1978
47cd99a4 1979=item sockatmark
80cbd5ad
JH
1980
1981A relatively recent addition to socket functions, may not
1982be implemented even in UNIX platforms.
1983
47cd99a4 1984=item socketpair
e41182b5 1985
016930a6
JM
1986Not implemented. (Win32, S<RISC OS>, VOS, VM/ESA)
1987
1988Available on 64 bit OpenVMS 8.2 and later. (VMS)
e41182b5 1989
e41182b5
GS
1990=item stat
1991
d62e1b7f
JH
1992Platforms that do not have rdev, blksize, or blocks will return these
1993as '', so numeric comparison or manipulation of these fields may cause
1994'not numeric' warnings.
1995
e41182b5 1996mtime and atime are the same thing, and ctime is creation time instead of
3f1f789b
JH
1997inode change time. (S<Mac OS>).
1998
1999ctime not supported on UFS (S<Mac OS X>).
e41182b5 2000
95a3fe12
MS
2001ctime is creation time instead of inode change time (Win32).
2002
e41182b5
GS
2003device and inode are not meaningful. (Win32)
2004
2005device and inode are not necessarily reliable. (VMS)
2006
b8099c3d
CN
2007mtime, atime and ctime all return the last modification time. Device and
2008inode are not necessarily reliable. (S<RISC OS>)
2009
d62e1b7f
JH
2010dev, rdev, blksize, and blocks are not available. inode is not
2011meaningful and will differ between stat calls on the same file. (os2)
2012
73e9292c
JH
2013some versions of cygwin when doing a stat("foo") and if not finding it
2014may then attempt to stat("foo.exe") (Cygwin)
2015
47cd99a4 2016=item symlink
e41182b5 2017
b8099c3d 2018Not implemented. (Win32, VMS, S<RISC OS>)
e41182b5 2019
47cd99a4 2020=item syscall
e41182b5 2021
7c5ffed3 2022Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA)
e41182b5 2023
47cd99a4 2024=item sysopen
f34d0673 2025
dd9f0070 2026The traditional "0", "1", and "2" MODEs are implemented with different
322422de
GS
2027numeric values on some systems. The flags exported by C<Fcntl>
2028(O_RDONLY, O_WRONLY, O_RDWR) should work everywhere though. (S<Mac
7c5ffed3 2029OS>, OS/390, VM/ESA)
f34d0673 2030
47cd99a4 2031=item system
e41182b5
GS
2032
2033Only implemented if ToolServer is installed. (S<Mac OS>)
2034
2035As an optimization, may not call the command shell specified in
b7df3edc 2036C<$ENV{PERL5SHELL}>. C<system(1, @args)> spawns an external
e41182b5
GS
2037process and immediately returns its process designator, without
2038waiting for it to terminate. Return value may be used subsequently
63f87e49
GS
2039in C<wait> or C<waitpid>. Failure to spawn() a subprocess is indicated
2040by setting $? to "255 << 8". C<$?> is set in a way compatible with
2041Unix (i.e. the exitstatus of the subprocess is obtained by "$? >> 8",
2042as described in the documentation). (Win32)
e41182b5 2043
b8099c3d
CN
2044There is no shell to process metacharacters, and the native standard is
2045to pass a command line terminated by "\n" "\r" or "\0" to the spawned
c47ff5f1 2046program. Redirection such as C<< > foo >> is performed (if at all) by
b8099c3d
CN
2047the run time library of the spawned program. C<system> I<list> will call
2048the Unix emulation library's C<exec> emulation, which attempts to provide
2049emulation of the stdin, stdout, stderr in force in the parent, providing
2050the child program uses a compatible version of the emulation library.
2051I<scalar> will call the native command line direct and no such emulation
2052of a child Unix program will exists. Mileage B<will> vary. (S<RISC OS>)
2053
433acd8a
JH
2054Far from being POSIX compliant. Because there may be no underlying
2055/bin/sh tries to work around the problem by forking and execing the
9b63e9ec 2056first token in its argument string. Handles basic redirection
c47ff5f1 2057("<" or ">") on its own behalf. (MiNT)
433acd8a 2058
0f897271
GS
2059Does not automatically flush output handles on some platforms.
2060(SunOS, Solaris, HP-UX)
2061
9bc98430
CB
2062The return value is POSIX-like (shifted up by 8 bits), which only allows
2063room for a made-up value derived from the severity bits of the native
206432-bit condition code (unless overridden by C<use vmsish 'status'>).
016930a6
JM
2065If the native condition code is one that has a POSIX value encoded, the
2066POSIX value will be decoded to extract the expected exit value.
9bc98430
CB
2067For more details see L<perlvms/$?>. (VMS)
2068
e41182b5
GS
2069=item times
2070
2071Only the first entry returned is nonzero. (S<Mac OS>)
2072
63f87e49
GS
2073"cumulative" times will be bogus. On anything other than Windows NT
2074or Windows 2000, "system" time will be bogus, and "user" time is
2075actually the time returned by the clock() function in the C runtime
2076library. (Win32)
e41182b5 2077
b8099c3d
CN
2078Not useful. (S<RISC OS>)
2079
47cd99a4 2080=item truncate
e41182b5 2081
6d738113 2082Not implemented. (Older versions of VMS)
e41182b5 2083
3fd80bd6 2084Truncation to same-or-shorter lengths only. (VOS)
495c5fdc 2085
4cfdb94f 2086If a FILEHANDLE is supplied, it must be writable and opened in append
e71a7dc8 2087mode (i.e., use C<<< open(FH, '>>filename') >>>
4cfdb94f
GS
2088or C<sysopen(FH,...,O_APPEND|O_RDWR)>. If a filename is supplied, it
2089should not be held open elsewhere. (Win32)
2090
e41182b5
GS
2091=item umask
2092
2093Returns undef where unavailable, as of version 5.005.
2094
b7df3edc
GS
2095C<umask> works but the correct permissions are set only when the file
2096is finally closed. (AmigaOS)
433acd8a 2097
47cd99a4 2098=item utime
e41182b5 2099
15c65113 2100Only the modification time is updated. (S<BeOS>, S<Mac OS>, VMS, S<RISC OS>)
e41182b5 2101
322422de
GS
2102May not behave as expected. Behavior depends on the C runtime
2103library's implementation of utime(), and the filesystem being
2104used. The FAT filesystem typically does not support an "access
2105time" field, and it may limit timestamps to a granularity of
2106two seconds. (Win32)
e41182b5
GS
2107
2108=item wait
2109
47cd99a4 2110=item waitpid
e41182b5 2111
3fd80bd6 2112Not implemented. (S<Mac OS>)
e41182b5
GS
2113
2114Can only be applied to process handles returned for processes spawned
a6f858fb 2115using C<system(1, ...)> or pseudo processes created with C<fork()>. (Win32)
e41182b5 2116
b8099c3d
CN
2117Not useful. (S<RISC OS>)
2118
e41182b5
GS
2119=back
2120
2121
ba58ab26
JH
2122=head1 Supported Platforms
2123
522b859a 2124As of July 2002 (the Perl release 5.8.0), the following platforms are
cec2c193
JH
2125able to build Perl from the standard source code distribution
2126available at http://www.cpan.org/src/index.html
2127
2128 AIX
2129 BeOS
6f683aa2 2130 BSD/OS (BSDi)
cec2c193
JH
2131 Cygwin
2132 DG/UX
811b48f2 2133 DOS DJGPP 1)
cec2c193
JH
2134 DYNIX/ptx
2135 EPOC R5
2136 FreeBSD
6f683aa2 2137 HI-UXMPP (Hitachi) (5.8.0 worked but we didn't know it)
cec2c193
JH
2138 HP-UX
2139 IRIX
2140 Linux
8939ba94 2141 Mac OS Classic
6f683aa2 2142 Mac OS X (Darwin)
cec2c193
JH
2143 MPE/iX
2144 NetBSD
2145 NetWare
2146 NonStop-UX
6f683aa2 2147 ReliantUNIX (formerly SINIX)
cec2c193 2148 OpenBSD
6f683aa2 2149 OpenVMS (formerly VMS)
3ebac25b 2150 Open UNIX (Unixware) (since Perl 5.8.1/5.9.0)
cec2c193 2151 OS/2
522b859a 2152 OS/400 (using the PASE) (since Perl 5.8.1/5.9.0)
70de81db 2153 PowerUX
6f683aa2 2154 POSIX-BC (formerly BS2000)
cec2c193
JH
2155 QNX
2156 Solaris
70de81db 2157 SunOS 4
6f683aa2
JH
2158 SUPER-UX (NEC)
2159 Tru64 UNIX (formerly DEC OSF/1, Digital UNIX)
cec2c193
JH
2160 UNICOS
2161 UNICOS/mk
2162 UTS
2163 VOS
811b48f2 2164 Win95/98/ME/2K/XP 2)
c40b5d1d 2165 WinCE
6f683aa2 2166 z/OS (formerly OS/390)
cec2c193 2167 VM/ESA
ba58ab26 2168
811b48f2
JH
2169 1) in DOS mode either the DOS or OS/2 ports can be used
2170 2) compilers: Borland, MinGW (GCC), VC6
cec2c193 2171
c40b5d1d 2172The following platforms worked with the previous releases (5.6 and
cec2c193
JH
21735.7), but we did not manage either to fix or to test these in time
2174for the 5.8.0 release. There is a very good chance that many of these
70de81db 2175will work fine with the 5.8.0.
cec2c193 2176
8da2b1be 2177 BSD/OS
cec2c193
JH
2178 DomainOS
2179 Hurd
2180 LynxOS
2181 MachTen
2182 PowerMAX
2183 SCO SV
cec2c193
JH
2184 SVR4
2185 Unixware
2186 Windows 3.1
ba58ab26 2187
70de81db
JH
2188Known to be broken for 5.8.0 (but 5.6.1 and 5.7.2 can be used):
2189
2190 AmigaOS
2191
ba58ab26 2192The following platforms have been known to build Perl from source in
fd46a41b
JH
2193the past (5.005_03 and earlier), but we haven't been able to verify
2194their status for the current release, either because the
2195hardware/software platforms are rare or because we don't have an
2196active champion on these platforms--or both. They used to work,
2197though, so go ahead and try compiling them, and let perlbug@perl.org
2198of any trouble.
ba58ab26 2199
cec2c193
JH
2200 3b1
2201 A/UX
cec2c193
JH
2202 ConvexOS
2203 CX/UX
2204 DC/OSx
2205 DDE SMES
2206 DOS EMX
2207 Dynix
2208 EP/IX
2209 ESIX
2210 FPS
2211 GENIX
2212 Greenhills
2213 ISC
2214 MachTen 68k
2215 MiNT
2216 MPC
2217 NEWS-OS
2218 NextSTEP
2219 OpenSTEP
2220 Opus
2221 Plan 9
cec2c193 2222 RISC/os
8da2b1be 2223 SCO ODT/OSR
cec2c193
JH
2224 Stellar
2225 SVR2
2226 TI1500
2227 TitanOS
2228 Ultrix
2229 Unisys Dynix
ba58ab26
JH
2230
2231The following platforms have their own source code distributions and
1577cd80 2232binaries available via http://www.cpan.org/ports/
ba58ab26 2233
cec2c193 2234 Perl release
ba58ab26 2235
522b859a 2236 OS/400 (ILE) 5.005_02
cec2c193 2237 Tandem Guardian 5.004
ba58ab26
JH
2238
2239The following platforms have only binaries available via
a93751fa 2240http://www.cpan.org/ports/index.html :
ba58ab26 2241
cec2c193 2242 Perl release
ba58ab26 2243
cec2c193
JH
2244 Acorn RISCOS 5.005_02
2245 AOS 5.002
2246 LynxOS 5.004_02
ba58ab26
JH
2247
2248Although we do suggest that you always build your own Perl from
2249the source code, both for maximal configurability and for security,
2250in case you are in a hurry you can check
a93751fa 2251http://www.cpan.org/ports/index.html for binary distributions.
ba58ab26 2252
c997b287
GS
2253=head1 SEE ALSO
2254
cec2c193 2255L<perlaix>, L<perlamiga>, L<perlapollo>, L<perlbeos>, L<perlbs2000>,
18a271bd 2256L<perlce>, L<perlcygwin>, L<perldgux>, L<perldos>, L<perlepoc>,
469e7be4 2257L<perlebcdic>, L<perlfreebsd>, L<perlhurd>, L<perlhpux>, L<perlirix>,
0d53b15f 2258L<perlmachten>, L<perlmacos>, L<perlmacosx>, L<perlmint>, L<perlmpeix>,
522b859a
JH
2259L<perlnetware>, L<perlos2>, L<perlos390>, L<perlos400>,
2260L<perlplan9>, L<perlqnx>, L<perlsolaris>, L<perltru64>,
2261L<perlunicode>, L<perlvmesa>, L<perlvms>, L<perlvos>,
2262L<perlwin32>, and L<Win32>.
c997b287 2263
e41182b5
GS
2264=head1 AUTHORS / CONTRIBUTORS
2265
06e9666b 2266Abigail <abigail@foad.org>,
c47ff5f1
GS
2267Charles Bailey <bailey@newman.upenn.edu>,
2268Graham Barr <gbarr@pobox.com>,
2269Tom Christiansen <tchrist@perl.com>,
06e9666b 2270Nicholas Clark <nick@ccl4.org>,
c47ff5f1 2271Thomas Dorner <Thomas.Dorner@start.de>,
06e9666b
A
2272Andy Dougherty <doughera@lafayette.edu>,
2273Dominic Dunlop <domo@computer.org>,
2274Neale Ferguson <neale@vma.tabnsw.com.au>,
c47ff5f1 2275David J. Fiander <davidf@mks.com>,
3fd80bd6 2276Paul Green <Paul.Green@stratus.com>,
06e9666b 2277M.J.T. Guy <mjtg@cam.ac.uk>,
61f30a5e 2278Jarkko Hietaniemi <jhi@iki.fi>,
c47ff5f1 2279Luther Huffman <lutherh@stratcom.com>,
06e9666b
A
2280Nick Ing-Simmons <nick@ing-simmons.net>,
2281Andreas J. KE<ouml>nig <a.koenig@mind.de>,
c47ff5f1
GS
2282Markus Laker <mlaker@contax.co.uk>,
2283Andrew M. Langmead <aml@world.std.com>,
2284Larry Moore <ljmoore@freespace.net>,
2285Paul Moore <Paul.Moore@uk.origin-it.com>,
2286Chris Nandor <pudge@pobox.com>,
1afc07ec 2287Matthias Neeracher <neeracher@mac.com>,
e71a7dc8 2288Philip Newton <pne@cpan.org>,
c47ff5f1
GS
2289Gary Ng <71564.1743@CompuServe.COM>,
2290Tom Phoenix <rootbeer@teleport.com>,
2291AndrE<eacute> Pirard <A.Pirard@ulg.ac.be>,
2292Peter Prymmer <pvhp@forte.com>,
2293Hugo van der Sanden <hv@crypt0.demon.co.uk>,
2294Gurusamy Sarathy <gsar@activestate.com>,
2295Paul J. Schinder <schinder@pobox.com>,
2296Michael G Schwern <schwern@pobox.com>,
06e9666b 2297Dan Sugalski <dan@sidhe.org>,
c47ff5f1 2298Nathan Torkington <gnat@frii.com>.
016930a6 2299John Malmberg <wb8tyw@qsl.net>