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1 | =head1 NAME |
2 | |
3 | perlport - Writing portable Perl |
4 | |
e41182b5 |
5 | =head1 DESCRIPTION |
6 | |
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7 | Perl runs on numerous operating systems. While most of them share |
8 | much in common, they also have their own unique features. |
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9 | |
10 | This document is meant to help you to find out what constitutes portable |
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11 | Perl code. That way once you make a decision to write portably, |
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12 | you know where the lines are drawn, and you can stay within them. |
13 | |
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14 | There is a tradeoff between taking full advantage of one particular |
15 | type of computer and taking advantage of a full range of them. |
16 | Naturally, as you broaden your range and become more diverse, the |
17 | common factors drop, and you are left with an increasingly smaller |
18 | area of common ground in which you can operate to accomplish a |
19 | particular task. Thus, when you begin attacking a problem, it is |
20 | important to consider under which part of the tradeoff curve you |
21 | want to operate. Specifically, you must decide whether it is |
22 | important that the task that you are coding have the full generality |
23 | of being portable, or whether to just get the job done right now. |
24 | This is the hardest choice to be made. The rest is easy, because |
25 | Perl provides many choices, whichever way you want to approach your |
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26 | problem. |
27 | |
28 | Looking at it another way, writing portable code is usually about |
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29 | willfully limiting your available choices. Naturally, it takes |
30 | discipline and sacrifice to do that. The product of portability |
31 | and convenience may be a constant. You have been warned. |
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32 | |
33 | Be aware of two important points: |
34 | |
35 | =over 4 |
36 | |
37 | =item Not all Perl programs have to be portable |
38 | |
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39 | There is no reason you should not use Perl as a language to glue Unix |
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40 | tools together, or to prototype a Macintosh application, or to manage the |
41 | Windows registry. If it makes no sense to aim for portability for one |
42 | reason 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 | |
46 | Don't be fooled into thinking that it is hard to create portable Perl |
47 | code. It isn't. Perl tries its level-best to bridge the gaps between |
48 | what's available on different platforms, and all the means available to |
49 | use those features. Thus almost all Perl code runs on any machine |
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50 | without modification. But there are some significant issues in |
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51 | writing portable code, and this document is entirely about those issues. |
52 | |
53 | =back |
54 | |
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55 | Here's the general rule: When you approach a task commonly done |
56 | using a whole range of platforms, think about writing portable |
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57 | code. That way, you don't sacrifice much by way of the implementation |
58 | choices you can avail yourself of, and at the same time you can give |
59 | your users lots of platform choices. On the other hand, when you have to |
60 | take advantage of some unique feature of a particular platform, as is |
61 | often the case with systems programming (whether for Unix, Windows, |
62 | S<Mac OS>, VMS, etc.), consider writing platform-specific code. |
63 | |
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64 | When the code will run on only two or three operating systems, you |
65 | may need to consider only the differences of those particular systems. |
66 | The important thing is to decide where the code will run and to be |
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67 | deliberate in your decision. |
68 | |
69 | The material below is separated into three main sections: main issues of |
70 | portability (L<"ISSUES">, platform-specific issues (L<"PLATFORMS">, and |
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71 | built-in perl functions that behave differently on various ports |
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72 | (L<"FUNCTION IMPLEMENTATIONS">. |
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73 | |
74 | This information should not be considered complete; it includes possibly |
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75 | transient information about idiosyncrasies of some of the ports, almost |
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76 | all of which are in a state of constant evolution. Thus, this material |
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77 | should be considered a perpetual work in progress |
78 | (E<lt>IMG SRC="yellow_sign.gif" ALT="Under Construction"E<gt>). |
79 | |
e41182b5 |
80 | =head1 ISSUES |
81 | |
82 | =head2 Newlines |
83 | |
638bc118 |
84 | In most operating systems, lines in files are terminated by newlines. |
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85 | Just what is used as a newline may vary from OS to OS. Unix |
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86 | traditionally uses C<\012>, one type of DOSish I/O uses C<\015\012>, |
e41182b5 |
87 | and S<Mac OS> uses C<\015>. |
88 | |
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89 | Perl uses C<\n> to represent the "logical" newline, where what is |
90 | logical may depend on the platform in use. In MacPerl, C<\n> always |
91 | means C<\015>. In DOSish perls, C<\n> usually means C<\012>, but |
92 | when accessing a file in "text" mode, STDIO translates it to (or |
93 | from) C<\015\012>, depending on whether your reading or writing. |
94 | Unix does the same thing on ttys in canonical mode. C<\015\012> |
95 | is commonly referred to as CRLF. |
96 | |
97 | Because of the "text" mode translation, DOSish perls have limitations |
98 | in using C<seek> and C<tell> on a file accessed in "text" mode. |
99 | Stick to C<seek>-ing to locations you got from C<tell> (and no |
100 | others), and you are usually free to use C<seek> and C<tell> even |
101 | in "text" mode. Using C<seek> or C<tell> or other file operations |
102 | may be non-portable. If you use C<binmode> on a file, however, you |
103 | can usually C<seek> and C<tell> with arbitrary values in safety. |
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104 | |
105 | A common misconception in socket programming is that C<\n> eq C<\012> |
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106 | everywhere. When using protocols such as common Internet protocols, |
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107 | C<\012> and C<\015> are called for specifically, and the values of |
108 | the logical C<\n> and C<\r> (carriage return) are not reliable. |
109 | |
110 | print SOCKET "Hi there, client!\r\n"; # WRONG |
111 | print SOCKET "Hi there, client!\015\012"; # RIGHT |
112 | |
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113 | However, using C<\015\012> (or C<\cM\cJ>, or C<\x0D\x0A>) can be tedious |
114 | and unsightly, as well as confusing to those maintaining the code. As |
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115 | such, the Socket module supplies the Right Thing for those who want it. |
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116 | |
117 | use Socket qw(:DEFAULT :crlf); |
118 | print SOCKET "Hi there, client!$CRLF" # RIGHT |
119 | |
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120 | When reading from a socket, remember that the default input record |
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121 | separator C<$/> is C<\n>, but robust socket code will recognize as |
122 | either C<\012> or C<\015\012> as end of line: |
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123 | |
124 | while (<SOCKET>) { |
125 | # ... |
126 | } |
127 | |
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128 | Because both CRLF and LF end in LF, the input record separator can |
129 | be set to LF and any CR stripped later. Better to write: |
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130 | |
131 | use Socket qw(:DEFAULT :crlf); |
132 | local($/) = LF; # not needed if $/ is already \012 |
133 | |
134 | while (<SOCKET>) { |
135 | s/$CR?$LF/\n/; # not sure if socket uses LF or CRLF, OK |
136 | # s/\015?\012/\n/; # same thing |
137 | } |
138 | |
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139 | This example is preferred over the previous one--even for Unix |
140 | platforms--because now any C<\015>'s (C<\cM>'s) are stripped out |
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141 | (and there was much rejoicing). |
142 | |
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143 | Similarly, functions that return text data--such as a function that |
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144 | fetches a web page--should sometimes translate newlines before |
145 | returning the data, if they've not yet been translated to the local |
146 | newline representation. A single line of code will often suffice: |
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147 | |
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148 | $data =~ s/\015?\012/\n/g; |
149 | return $data; |
2ee0eb3c |
150 | |
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151 | Some of this may be confusing. Here's a handy reference to the ASCII CR |
152 | and LF characters. You can print it out and stick it in your wallet. |
153 | |
154 | LF == \012 == \x0A == \cJ == ASCII 10 |
155 | CR == \015 == \x0D == \cM == ASCII 13 |
156 | |
157 | | Unix | DOS | Mac | |
158 | --------------------------- |
159 | \n | LF | LF | CR | |
160 | \r | CR | CR | LF | |
161 | \n * | LF | CRLF | CR | |
162 | \r * | CR | CR | LF | |
163 | --------------------------- |
164 | * text-mode STDIO |
165 | |
b7df3edc |
166 | The Unix column assumes that you are not accessing a serial line |
167 | (like a tty) in canonical mode. If you are, then CR on input becomes |
168 | "\n", and "\n" on output becomes CRLF. |
169 | |
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170 | These are just the most common definitions of C<\n> and C<\r> in Perl. |
171 | There may well be others. |
172 | |
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173 | =head2 Numbers endianness and Width |
174 | |
175 | Different CPUs store integers and floating point numbers in different |
176 | orders (called I<endianness>) and widths (32-bit and 64-bit being the |
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177 | most common today). This affects your programs when they attempt to transfer |
178 | numbers in binary format from one CPU architecture to another, |
179 | usually either "live" via network connection, or by storing the |
180 | numbers to secondary storage such as a disk file or tape. |
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181 | |
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182 | Conflicting storage orders make utter mess out of the numbers. If a |
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183 | little-endian host (Intel, Alpha) stores 0x12345678 (305419896 in |
184 | decimal), a big-endian host (Motorola, MIPS, Sparc, PA) reads it as |
185 | 0x78563412 (2018915346 in decimal). To avoid this problem in network |
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186 | (socket) connections use the C<pack> and C<unpack> formats C<n> |
b7df3edc |
187 | and C<N>, the "network" orders. These are guaranteed to be portable. |
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188 | |
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189 | Differing widths can cause truncation even between platforms of equal |
190 | endianness. The platform of shorter width loses the upper parts of the |
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191 | number. There is no good solution for this problem except to avoid |
192 | transferring or storing raw binary numbers. |
193 | |
b7df3edc |
194 | One can circumnavigate both these problems in two ways. Either |
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195 | transfer and store numbers always in text format, instead of raw |
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196 | binary, or else consider using modules like Data::Dumper (included in |
197 | the standard distribution as of Perl 5.005) and Storable. Keeping |
198 | all data as text significantly simplifies matters. |
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199 | |
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200 | =head2 Files and Filesystems |
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201 | |
202 | Most platforms these days structure files in a hierarchical fashion. |
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203 | So, it is reasonably safe to assume that all platforms support the |
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204 | notion of a "path" to uniquely identify a file on the system. How |
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205 | that path is really written, though, differs considerably. |
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206 | |
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207 | Atlhough similar, file path specifications differ between Unix, |
208 | Windows, S<Mac OS>, OS/2, VMS, VOS, S<RISC OS>, and probably others. |
209 | Unix, for example, is one of the few OSes that has the elegant idea |
210 | of a single root directory. |
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211 | |
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212 | DOS, OS/2, VMS, VOS, and Windows can work similarly to Unix with C</> |
213 | as path separator, or in their own idiosyncratic ways (such as having |
214 | several root directories and various "unrooted" device files such NIL: |
215 | and LPT:). |
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216 | |
217 | S<Mac OS> uses C<:> as a path separator instead of C</>. |
218 | |
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219 | The filesystem may support neither hard links (C<link>) nor |
220 | symbolic links (C<symlink>, C<readlink>, C<lstat>). |
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221 | |
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222 | The filesystem may support neither access timestamp nor change |
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223 | timestamp (meaning that about the only portable timestamp is the |
224 | modification timestamp), or one second granularity of any timestamps |
225 | (e.g. the FAT filesystem limits the time granularity to two seconds). |
226 | |
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227 | VOS perl can emulate Unix filenames with C</> as path separator. The |
228 | native pathname characters greater-than, less-than, number-sign, and |
229 | percent-sign are always accepted. |
230 | |
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231 | S<RISC OS> perl can emulate Unix filenames with C</> as path |
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232 | separator, or go native and use C<.> for path separator and C<:> to |
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233 | signal filesystems and disk names. |
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234 | |
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235 | If all this is intimidating, have no (well, maybe only a little) |
236 | fear. There are modules that can help. The File::Spec modules |
237 | provide methods to do the Right Thing on whatever platform happens |
238 | to be running the program. |
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239 | |
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240 | use File::Spec::Functions; |
241 | chdir(updir()); # go up one directory |
242 | $file = catfile(curdir(), 'temp', 'file.txt'); |
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243 | # on Unix and Win32, './temp/file.txt' |
244 | # on Mac OS, ':temp:file.txt' |
245 | |
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246 | File::Spec is available in the standard distribution as of version |
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247 | 5.004_05. |
248 | |
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249 | In general, production code should not have file paths hardcoded. |
250 | Making them user-supplied or read from a configuration file is |
251 | better, keeping in mind that file path syntax varies on different |
252 | machines. |
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253 | |
254 | This is especially noticeable in scripts like Makefiles and test suites, |
255 | which often assume C</> as a path separator for subdirectories. |
256 | |
b7df3edc |
257 | Also of use is File::Basename from the standard distribution, which |
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258 | splits a pathname into pieces (base filename, full path to directory, |
259 | and file suffix). |
260 | |
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261 | Even when on a single platform (if you can call Unix a single platform), |
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262 | remember not to count on the existence or the contents of particular |
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263 | system-specific files or directories, like F</etc/passwd>, |
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264 | F</etc/sendmail.conf>, F</etc/resolv.conf>, or even F</tmp/>. For |
265 | example, F</etc/passwd> may exist but not contain the encrypted |
266 | passwords, because the system is using some form of enhanced security. |
267 | Or it may not contain all the accounts, because the system is using NIS. |
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268 | If code does need to rely on such a file, include a description of the |
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269 | file and its format in the code's documentation, then make it easy for |
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270 | the user to override the default location of the file. |
271 | |
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272 | Don't assume a text file will end with a newline. They should, |
273 | but people forget. |
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274 | |
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275 | Do not have two files of the same name with different case, like |
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276 | F<test.pl> and F<Test.pl>, as many platforms have case-insensitive |
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277 | filenames. Also, try not to have non-word characters (except for C<.>) |
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278 | in the names, and keep them to the 8.3 convention, for maximum |
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279 | portability, onerous a burden though this may appear. |
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280 | |
b7df3edc |
281 | Likewise, when using the AutoSplit module, try to keep your functions to |
282 | 8.3 naming and case-insensitive conventions; or, at the least, |
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283 | make it so the resulting files have a unique (case-insensitively) |
284 | first 8 characters. |
285 | |
b7df3edc |
286 | Whitespace in filenames is tolerated on most systems, but not all. |
287 | Many systems (DOS, VMS) cannot have more than one C<.> in their filenames. |
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288 | |
289 | Don't assume C<E<gt>> won't be the first character of a filename. |
b7df3edc |
290 | Always use C<E<lt>> explicitly to open a file for reading, |
291 | unless you want the user to be able to specify a pipe open. |
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292 | |
6ab3f9cb |
293 | open(FILE, "< $existing_file") or die $!; |
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294 | |
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295 | If filenames might use strange characters, it is safest to open it |
296 | with C<sysopen> instead of C<open>. C<open> is magic and can |
297 | translate characters like C<E<gt>>, C<E<lt>>, and C<|>, which may |
b7df3edc |
298 | be the wrong thing to do. (Sometimes, though, it's the right thing.) |
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299 | |
300 | =head2 System Interaction |
301 | |
b7df3edc |
302 | Not all platforms provide a command line. These are usually platforms |
303 | that rely primarily on a Graphical User Interface (GUI) for user |
304 | interaction. A program requiring a command line interface might |
305 | not work everywhere. This is probably for the user of the program |
306 | to deal with, so don't stay up late worrying about it. |
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307 | |
b7df3edc |
308 | Some platforms can't delete or rename files held open by the system. |
309 | Remember to C<close> files when you are done with them. Don't |
310 | C<unlink> or C<rename> an open file. Don't C<tie> or C<open> a |
311 | file already tied or opened; C<untie> or C<close> it first. |
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312 | |
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313 | Don't open the same file more than once at a time for writing, as some |
314 | operating systems put mandatory locks on such files. |
315 | |
e41182b5 |
316 | Don't count on a specific environment variable existing in C<%ENV>. |
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317 | Don't count on C<%ENV> entries being case-sensitive, or even |
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318 | case-preserving. |
319 | |
6ab3f9cb |
320 | Don't count on signals for anything. |
e41182b5 |
321 | |
322 | Don't count on filename globbing. Use C<opendir>, C<readdir>, and |
323 | C<closedir> instead. |
324 | |
b8099c3d |
325 | Don't count on per-program environment variables, or per-program current |
dd9f0070 |
326 | directories. |
b8099c3d |
327 | |
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328 | Don't count on specific values of C<$!>. |
329 | |
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330 | =head2 Interprocess Communication (IPC) |
331 | |
b7df3edc |
332 | In general, don't directly access the system in code meant to be |
333 | portable. That means, no C<system>, C<exec>, C<fork>, C<pipe>, |
334 | C<``>, C<qx//>, C<open> with a C<|>, nor any of the other things |
335 | that makes being a perl hacker worth being. |
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336 | |
337 | Commands that launch external processes are generally supported on |
b7df3edc |
338 | most platforms (though many of them do not support any type of |
339 | forking). The problem with using them arises from what you invoke |
340 | them on. External tools are often named differently on different |
341 | platforms, may not be available in the same location, migth accept |
342 | different arguments, can behave differently, and often present their |
343 | results in a platform-dependent way. Thus, you should seldom depend |
344 | on them to produce consistent results. (Then again, if you're calling |
345 | I<netstat -a>, you probably don't expect it to run on both Unix and CP/M.) |
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346 | |
b7df3edc |
347 | One especially common bit of Perl code is opening a pipe to B<sendmail>: |
e41182b5 |
348 | |
b7df3edc |
349 | open(MAIL, '|/usr/lib/sendmail -t') |
350 | or die "cannot fork sendmail: $!"; |
e41182b5 |
351 | |
352 | This is fine for systems programming when sendmail is known to be |
353 | available. But it is not fine for many non-Unix systems, and even |
354 | some Unix systems that may not have sendmail installed. If a portable |
b7df3edc |
355 | solution is needed, see the various distributions on CPAN that deal |
356 | with it. Mail::Mailer and Mail::Send in the MailTools distribution are |
357 | commonly used, and provide several mailing methods, including mail, |
358 | sendmail, and direct SMTP (via Net::SMTP) if a mail transfer agent is |
359 | not available. Mail::Sendmail is a standalone module that provides |
360 | simple, platform-independent mailing. |
361 | |
362 | The Unix System V IPC (C<msg*(), sem*(), shm*()>) is not available |
363 | even on all Unix platforms. |
e41182b5 |
364 | |
365 | The rule of thumb for portable code is: Do it all in portable Perl, or |
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366 | use a module (that may internally implement it with platform-specific |
367 | code, but expose a common interface). |
e41182b5 |
368 | |
e41182b5 |
369 | =head2 External Subroutines (XS) |
370 | |
b7df3edc |
371 | XS code can usually be made to work with any platform, but dependent |
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372 | libraries, header files, etc., might not be readily available or |
373 | portable, or the XS code itself might be platform-specific, just as Perl |
374 | code might be. If the libraries and headers are portable, then it is |
375 | normally reasonable to make sure the XS code is portable, too. |
376 | |
b7df3edc |
377 | A different type of portability issue arises when writing XS code: |
378 | availability of a C compiler on the end-user's system. C brings |
379 | with it its own portability issues, and writing XS code will expose |
380 | you to some of those. Writing purely in Perl is an easier way to |
e41182b5 |
381 | achieve portability. |
382 | |
e41182b5 |
383 | =head2 Standard Modules |
384 | |
385 | In general, the standard modules work across platforms. Notable |
6ab3f9cb |
386 | exceptions are the CPAN module (which currently makes connections to external |
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387 | programs that may not be available), platform-specific modules (like |
6ab3f9cb |
388 | ExtUtils::MM_VMS), and DBM modules. |
e41182b5 |
389 | |
b7df3edc |
390 | There is no one DBM module available on all platforms. |
6ab3f9cb |
391 | SDBM_File and the others are generally available on all Unix and DOSish |
392 | ports, but not in MacPerl, where only NBDM_File and DB_File are |
0a47030a |
393 | available. |
e41182b5 |
394 | |
395 | The good news is that at least some DBM module should be available, and |
6ab3f9cb |
396 | AnyDBM_File will use whichever module it can find. Of course, then |
b7df3edc |
397 | the code needs to be fairly strict, dropping to the greatest common |
398 | factor (e.g., not exceeding 1K for each record), so that it will |
6ab3f9cb |
399 | work with any DBM module. See L<AnyDBM_File> for more details. |
e41182b5 |
400 | |
e41182b5 |
401 | =head2 Time and Date |
402 | |
0a47030a |
403 | The system's notion of time of day and calendar date is controlled in |
b7df3edc |
404 | widely different ways. Don't assume the timezone is stored in C<$ENV{TZ}>, |
0a47030a |
405 | and even if it is, don't assume that you can control the timezone through |
406 | that variable. |
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407 | |
322422de |
408 | Don't assume that the epoch starts at 00:00:00, January 1, 1970, |
6ab3f9cb |
409 | because that is OS- and implementation-specific. It is better to store a date |
410 | in an unambiguous representation. The ISO-8601 standard defines |
411 | "YYYY-MM-DD" as the date format. A text representation (like "1987-12-18") |
412 | can be easily converted into an OS-specific value using a module like |
413 | Date::Parse. An array of values, such as those returned by |
322422de |
414 | C<localtime>, can be converted to an OS-specific representation using |
6ab3f9cb |
415 | Time::Local. |
322422de |
416 | |
19799a22 |
417 | When calculating specific times, such as for tests in time or date modules, |
418 | it may be appropriate to calculate an offset for the epoch. |
b7df3edc |
419 | |
19799a22 |
420 | require Time::Local; |
421 | $offset = Time::Local::timegm(0, 0, 0, 1, 0, 70); |
b7df3edc |
422 | |
19799a22 |
423 | The value for C<$offset> in Unix will be C<0>, but in Mac OS will be |
424 | some large number. C<$offset> can then be added to a Unix time value |
425 | to get what should be the proper value on any system. |
322422de |
426 | |
427 | =head2 Character sets and character encoding |
428 | |
b7df3edc |
429 | Assume little about character sets. Assume nothing about |
430 | numerical values (C<ord>, C<chr>) of characters. Do not |
322422de |
431 | assume that the alphabetic characters are encoded contiguously (in |
b7df3edc |
432 | the numeric sense). Do not assume anything about the ordering of the |
322422de |
433 | characters. The lowercase letters may come before or after the |
b7df3edc |
434 | uppercase letters; the lowercase and uppercase may be interlaced so |
435 | that both `a' and `A' come before `b'; the accented and other |
322422de |
436 | international characters may be interlaced so that E<auml> comes |
b7df3edc |
437 | before `b'. |
322422de |
438 | |
439 | =head2 Internationalisation |
440 | |
b7df3edc |
441 | If you may assume POSIX (a rather large assumption), you may read |
442 | more about the POSIX locale system from L<perllocale>. The locale |
443 | system at least attempts to make things a little bit more portable, |
444 | or at least more convenient and native-friendly for non-English |
445 | users. The system affects character sets and encoding, and date |
446 | and time formatting--amongst other things. |
e41182b5 |
447 | |
448 | =head2 System Resources |
449 | |
0a47030a |
450 | If your code is destined for systems with severely constrained (or |
451 | missing!) virtual memory systems then you want to be I<especially> mindful |
452 | of avoiding wasteful constructs such as: |
e41182b5 |
453 | |
454 | # NOTE: this is no longer "bad" in perl5.005 |
455 | for (0..10000000) {} # bad |
456 | for (my $x = 0; $x <= 10000000; ++$x) {} # good |
457 | |
458 | @lines = <VERY_LARGE_FILE>; # bad |
459 | |
460 | while (<FILE>) {$file .= $_} # sometimes bad |
0a47030a |
461 | $file = join('', <FILE>); # better |
e41182b5 |
462 | |
b7df3edc |
463 | The last two constructs may appear unintuitive to most people. The |
464 | first repeatedly grows a string, whereas the second allocates a |
465 | large chunk of memory in one go. On some systems, the second is |
466 | more efficient that the first. |
0a47030a |
467 | |
e41182b5 |
468 | =head2 Security |
469 | |
b7df3edc |
470 | Most multi-user platforms provide basic levels of security, usually |
471 | implemented at the filesystem level. Some, however, do |
472 | not--unfortunately. Thus the notion of user id, or "home" directory, |
473 | or even the state of being logged-in, may be unrecognizable on many |
474 | platforms. If you write programs that are security-conscious, it |
475 | is usually best to know what type of system you will be running |
476 | under so that you can write code explicitly for that platform (or |
477 | class of platforms). |
0a47030a |
478 | |
e41182b5 |
479 | =head2 Style |
480 | |
481 | For those times when it is necessary to have platform-specific code, |
482 | consider keeping the platform-specific code in one place, making porting |
6ab3f9cb |
483 | to other platforms easier. Use the Config module and the special |
0a47030a |
484 | variable C<$^O> to differentiate platforms, as described in |
485 | L<"PLATFORMS">. |
e41182b5 |
486 | |
b7df3edc |
487 | Be careful in the tests you supply with your module or programs. |
488 | Module code may be fully portable, but its tests might not be. This |
489 | often happens when tests spawn off other processes or call external |
490 | programs to aid in the testing, or when (as noted above) the tests |
491 | assume certain things about the filesystem and paths. Be careful |
492 | not to depend on a specific output style for errors, such as when |
493 | checking C<$!> after an system call. Some platforms expect a certain |
494 | output format, and perl on those platforms may have been adjusted |
495 | accordingly. Most specifically, don't anchor a regex when testing |
496 | an error value. |
e41182b5 |
497 | |
0a47030a |
498 | =head1 CPAN Testers |
e41182b5 |
499 | |
0a47030a |
500 | Modules uploaded to CPAN are tested by a variety of volunteers on |
501 | different platforms. These CPAN testers are notified by mail of each |
e41182b5 |
502 | new upload, and reply to the list with PASS, FAIL, NA (not applicable to |
0a47030a |
503 | this platform), or UNKNOWN (unknown), along with any relevant notations. |
e41182b5 |
504 | |
505 | The purpose of the testing is twofold: one, to help developers fix any |
0a47030a |
506 | problems in their code that crop up because of lack of testing on other |
b7df3edc |
507 | platforms; two, to provide users with information about whether |
0a47030a |
508 | a given module works on a given platform. |
e41182b5 |
509 | |
510 | =over 4 |
511 | |
512 | =item Mailing list: cpan-testers@perl.org |
513 | |
6ab3f9cb |
514 | =item Testing results: C<http://www.perl.org/cpan-testers/> |
e41182b5 |
515 | |
516 | =back |
517 | |
e41182b5 |
518 | =head1 PLATFORMS |
519 | |
520 | As of version 5.002, Perl is built with a C<$^O> variable that |
521 | indicates the operating system it was built on. This was implemented |
b7df3edc |
522 | to help speed up code that would otherwise have to C<use Config> |
523 | and use the value of C<$Config{osname}>. Of course, to get more |
e41182b5 |
524 | detailed information about the system, looking into C<%Config> is |
525 | certainly recommended. |
526 | |
b7df3edc |
527 | C<%Config> cannot always be trusted, however, because it was built |
528 | at compile time. If perl was built in one place, then transferred |
529 | elsewhere, some values may be wrong. The values may even have been |
530 | edited after the fact. |
6ab3f9cb |
531 | |
e41182b5 |
532 | =head2 Unix |
533 | |
534 | Perl works on a bewildering variety of Unix and Unix-like platforms (see |
535 | e.g. most of the files in the F<hints/> directory in the source code kit). |
536 | On most of these systems, the value of C<$^O> (hence C<$Config{'osname'}>, |
537 | too) is determined by lowercasing and stripping punctuation from the first |
0a47030a |
538 | field of the string returned by typing C<uname -a> (or a similar command) |
539 | at the shell prompt. Here, for example, are a few of the more popular |
540 | Unix flavors: |
e41182b5 |
541 | |
b7df3edc |
542 | uname $^O $Config{'archname'} |
6ab3f9cb |
543 | -------------------------------------------- |
b7df3edc |
544 | AIX aix aix |
6ab3f9cb |
545 | BSD/OS bsdos i386-bsdos |
546 | dgux dgux AViiON-dgux |
547 | DYNIX/ptx dynixptx i386-dynixptx |
b7df3edc |
548 | FreeBSD freebsd freebsd-i386 |
549 | Linux linux i386-linux |
6ab3f9cb |
550 | Linux linux i586-linux |
551 | Linux linux ppc-linux |
b7df3edc |
552 | HP-UX hpux PA-RISC1.1 |
553 | IRIX irix irix |
6ab3f9cb |
554 | openbsd openbsd i386-openbsd |
b7df3edc |
555 | OSF1 dec_osf alpha-dec_osf |
6ab3f9cb |
556 | reliantunix-n svr4 RM400-svr4 |
557 | SCO_SV sco_sv i386-sco_sv |
558 | SINIX-N svr4 RM400-svr4 |
559 | sn4609 unicos CRAY_C90-unicos |
560 | sn6521 unicosmk t3e-unicosmk |
561 | sn9617 unicos CRAY_J90-unicos |
b7df3edc |
562 | SunOS solaris sun4-solaris |
563 | SunOS solaris i86pc-solaris |
564 | SunOS4 sunos sun4-sunos |
e41182b5 |
565 | |
b7df3edc |
566 | Because the value of C<$Config{archname}> may depend on the |
567 | hardware architecture, it can vary more than the value of C<$^O>. |
6ab3f9cb |
568 | |
e41182b5 |
569 | =head2 DOS and Derivatives |
570 | |
b7df3edc |
571 | Perl has long been ported to Intel-style microcomputers running under |
e41182b5 |
572 | systems like PC-DOS, MS-DOS, OS/2, and most Windows platforms you can |
573 | bring yourself to mention (except for Windows CE, if you count that). |
b7df3edc |
574 | Users familiar with I<COMMAND.COM> or I<CMD.EXE> style shells should |
e41182b5 |
575 | be aware that each of these file specifications may have subtle |
576 | differences: |
577 | |
578 | $filespec0 = "c:/foo/bar/file.txt"; |
579 | $filespec1 = "c:\\foo\\bar\\file.txt"; |
580 | $filespec2 = 'c:\foo\bar\file.txt'; |
581 | $filespec3 = 'c:\\foo\\bar\\file.txt'; |
582 | |
b7df3edc |
583 | System calls accept either C</> or C<\> as the path separator. |
584 | However, many command-line utilities of DOS vintage treat C</> as |
585 | the option prefix, so may get confused by filenames containing C</>. |
586 | Aside from calling any external programs, C</> will work just fine, |
587 | and probably better, as it is more consistent with popular usage, |
588 | and avoids the problem of remembering what to backwhack and what |
589 | not to. |
e41182b5 |
590 | |
b7df3edc |
591 | The DOS FAT filesystem can accommodate only "8.3" style filenames. Under |
592 | the "case-insensitive, but case-preserving" HPFS (OS/2) and NTFS (NT) |
0a47030a |
593 | filesystems you may have to be careful about case returned with functions |
e41182b5 |
594 | like C<readdir> or used with functions like C<open> or C<opendir>. |
595 | |
b7df3edc |
596 | DOS also treats several filenames as special, such as AUX, PRN, |
597 | NUL, CON, COM1, LPT1, LPT2, etc. Unfortunately, sometimes these |
598 | filenames won't even work if you include an explicit directory |
599 | prefix. It is best to avoid such filenames, if you want your code |
600 | to be portable to DOS and its derivatives. It's hard to know what |
601 | these all are, unfortunately. |
e41182b5 |
602 | |
603 | Users of these operating systems may also wish to make use of |
b7df3edc |
604 | scripts such as I<pl2bat.bat> or I<pl2cmd> to |
e41182b5 |
605 | put wrappers around your scripts. |
606 | |
607 | Newline (C<\n>) is translated as C<\015\012> by STDIO when reading from |
6ab3f9cb |
608 | and writing to files (see L<"Newlines">). C<binmode(FILEHANDLE)> |
609 | will keep C<\n> translated as C<\012> for that filehandle. Since it is a |
610 | no-op on other systems, C<binmode> should be used for cross-platform code |
b7df3edc |
611 | that deals with binary data. That's assuming you realize in advance |
612 | that your data is in binary. General-purpose programs should |
613 | often assume nothing about their data. |
e41182b5 |
614 | |
b7df3edc |
615 | The C<$^O> variable and the C<$Config{archname}> values for various |
e41182b5 |
616 | DOSish perls are as follows: |
617 | |
618 | OS $^O $Config{'archname'} |
619 | -------------------------------------------- |
620 | MS-DOS dos |
621 | PC-DOS dos |
622 | OS/2 os2 |
623 | Windows 95 MSWin32 MSWin32-x86 |
6ab3f9cb |
624 | Windows 98 MSWin32 MSWin32-x86 |
e41182b5 |
625 | Windows NT MSWin32 MSWin32-x86 |
6ab3f9cb |
626 | Windows NT MSWin32 MSWin32-ALPHA |
e41182b5 |
627 | Windows NT MSWin32 MSWin32-ppc |
628 | |
629 | Also see: |
630 | |
631 | =over 4 |
632 | |
633 | =item The djgpp environment for DOS, C<http://www.delorie.com/djgpp/> |
634 | |
635 | =item The EMX environment for DOS, OS/2, etc. C<emx@iaehv.nl>, |
2ee0eb3c |
636 | C<http://www.leo.org/pub/comp/os/os2/leo/gnu/emx+gcc/index.html> or |
637 | C<ftp://hobbes.nmsu.edu/pub/os2/dev/emx> |
e41182b5 |
638 | |
639 | =item Build instructions for Win32, L<perlwin32>. |
640 | |
641 | =item The ActiveState Pages, C<http://www.activestate.com/> |
642 | |
643 | =back |
644 | |
dd9f0070 |
645 | =head2 S<Mac OS> |
e41182b5 |
646 | |
647 | Any module requiring XS compilation is right out for most people, because |
648 | MacPerl is built using non-free (and non-cheap!) compilers. Some XS |
649 | modules that can work with MacPerl are built and distributed in binary |
6ab3f9cb |
650 | form on CPAN. |
e41182b5 |
651 | |
652 | Directories are specified as: |
653 | |
654 | volume:folder:file for absolute pathnames |
655 | volume:folder: for absolute pathnames |
656 | :folder:file for relative pathnames |
657 | :folder: for relative pathnames |
658 | :file for relative pathnames |
659 | file for relative pathnames |
660 | |
b7df3edc |
661 | Files are stored in the directory in alphabetical order. Filenames are |
6ab3f9cb |
662 | limited to 31 characters, and may include any character except for |
b7df3edc |
663 | null and C<:>, which is reserved as the path separator. |
e41182b5 |
664 | |
0a47030a |
665 | Instead of C<flock>, see C<FSpSetFLock> and C<FSpRstFLock> in the |
6ab3f9cb |
666 | Mac::Files module, or C<chmod(0444, ...)> and C<chmod(0666, ...)>. |
e41182b5 |
667 | |
668 | In the MacPerl application, you can't run a program from the command line; |
669 | programs that expect C<@ARGV> to be populated can be edited with something |
670 | like the following, which brings up a dialog box asking for the command |
671 | line arguments. |
672 | |
673 | if (!@ARGV) { |
674 | @ARGV = split /\s+/, MacPerl::Ask('Arguments?'); |
675 | } |
676 | |
b7df3edc |
677 | A MacPerl script saved as a "droplet" will populate C<@ARGV> with the full |
e41182b5 |
678 | pathnames of the files dropped onto the script. |
679 | |
b7df3edc |
680 | Mac users can run programs under a type of command line interface |
681 | under MPW (Macintosh Programmer's Workshop, a free development |
682 | environment from Apple). MacPerl was first introduced as an MPW |
683 | tool, and MPW can be used like a shell: |
e41182b5 |
684 | |
685 | perl myscript.plx some arguments |
686 | |
687 | ToolServer is another app from Apple that provides access to MPW tools |
0a47030a |
688 | from MPW and the MacPerl app, which allows MacPerl programs to use |
e41182b5 |
689 | C<system>, backticks, and piped C<open>. |
690 | |
691 | "S<Mac OS>" is the proper name for the operating system, but the value |
692 | in C<$^O> is "MacOS". To determine architecture, version, or whether |
693 | the application or MPW tool version is running, check: |
694 | |
695 | $is_app = $MacPerl::Version =~ /App/; |
696 | $is_tool = $MacPerl::Version =~ /MPW/; |
697 | ($version) = $MacPerl::Version =~ /^(\S+)/; |
698 | $is_ppc = $MacPerl::Architecture eq 'MacPPC'; |
699 | $is_68k = $MacPerl::Architecture eq 'Mac68K'; |
700 | |
6ab3f9cb |
701 | S<Mac OS X> and S<Mac OS X Server>, based on NeXT's OpenStep OS, will |
702 | (in theory) be able to run MacPerl natively, under the "Classic" |
703 | environment. The new "Cocoa" environment (formerly called the "Yellow Box") |
704 | may run a slightly modified version of MacPerl, using the Carbon interfaces. |
705 | |
706 | S<Mac OS X Server> and its Open Source version, Darwin, both run Unix |
b7df3edc |
707 | perl natively (with a few patches). Full support for these |
6ab3f9cb |
708 | is slated for perl5.006. |
709 | |
e41182b5 |
710 | Also see: |
711 | |
712 | =over 4 |
713 | |
6ab3f9cb |
714 | =item The MacPerl Pages, C<http://www.macperl.com/>. |
e41182b5 |
715 | |
6ab3f9cb |
716 | =item The MacPerl mailing lists, C<http://www.macperl.org/>. |
717 | |
718 | =item MacPerl Module Porters, C<http://pudge.net/mmp/>. |
e41182b5 |
719 | |
720 | =back |
721 | |
e41182b5 |
722 | =head2 VMS |
723 | |
724 | Perl on VMS is discussed in F<vms/perlvms.pod> in the perl distribution. |
b7df3edc |
725 | Perl on VMS can accept either VMS- or Unix-style file |
e41182b5 |
726 | specifications as in either of the following: |
727 | |
728 | $ perl -ne "print if /perl_setup/i" SYS$LOGIN:LOGIN.COM |
729 | $ perl -ne "print if /perl_setup/i" /sys$login/login.com |
730 | |
731 | but not a mixture of both as in: |
732 | |
733 | $ perl -ne "print if /perl_setup/i" sys$login:/login.com |
734 | Can't open sys$login:/login.com: file specification syntax error |
735 | |
736 | Interacting with Perl from the Digital Command Language (DCL) shell |
737 | often requires a different set of quotation marks than Unix shells do. |
738 | For example: |
739 | |
740 | $ perl -e "print ""Hello, world.\n""" |
741 | Hello, world. |
742 | |
b7df3edc |
743 | There are several ways to wrap your perl scripts in DCL F<.COM> files, if |
e41182b5 |
744 | you are so inclined. For example: |
745 | |
746 | $ write sys$output "Hello from DCL!" |
747 | $ if p1 .eqs. "" |
748 | $ then perl -x 'f$environment("PROCEDURE") |
749 | $ else perl -x - 'p1 'p2 'p3 'p4 'p5 'p6 'p7 'p8 |
750 | $ deck/dollars="__END__" |
751 | #!/usr/bin/perl |
752 | |
753 | print "Hello from Perl!\n"; |
754 | |
755 | __END__ |
756 | $ endif |
757 | |
758 | Do take care with C<$ ASSIGN/nolog/user SYS$COMMAND: SYS$INPUT> if your |
759 | perl-in-DCL script expects to do things like C<$read = E<lt>STDINE<gt>;>. |
760 | |
761 | Filenames are in the format "name.extension;version". The maximum |
762 | length for filenames is 39 characters, and the maximum length for |
763 | extensions is also 39 characters. Version is a number from 1 to |
764 | 32767. Valid characters are C</[A-Z0-9$_-]/>. |
765 | |
b7df3edc |
766 | VMS's RMS filesystem is case-insensitive and does not preserve case. |
e41182b5 |
767 | C<readdir> returns lowercased filenames, but specifying a file for |
b7df3edc |
768 | opening remains case-insensitive. Files without extensions have a |
e41182b5 |
769 | trailing period on them, so doing a C<readdir> with a file named F<A.;5> |
0a47030a |
770 | will return F<a.> (though that file could be opened with |
771 | C<open(FH, 'A')>). |
e41182b5 |
772 | |
f34d0673 |
773 | RMS had an eight level limit on directory depths from any rooted logical |
dd9f0070 |
774 | (allowing 16 levels overall) prior to VMS 7.2. Hence |
775 | C<PERL_ROOT:[LIB.2.3.4.5.6.7.8]> is a valid directory specification but |
776 | C<PERL_ROOT:[LIB.2.3.4.5.6.7.8.9]> is not. F<Makefile.PL> authors might |
777 | have to take this into account, but at least they can refer to the former |
f34d0673 |
778 | as C</PERL_ROOT/lib/2/3/4/5/6/7/8/>. |
e41182b5 |
779 | |
6ab3f9cb |
780 | The VMS::Filespec module, which gets installed as part of the build |
0a47030a |
781 | process on VMS, is a pure Perl module that can easily be installed on |
782 | non-VMS platforms and can be helpful for conversions to and from RMS |
783 | native formats. |
e41182b5 |
784 | |
b7df3edc |
785 | What C<\n> represents depends on the type of file opened. It could |
e41182b5 |
786 | be C<\015>, C<\012>, C<\015\012>, or nothing. Reading from a file |
787 | translates newlines to C<\012>, unless C<binmode> was executed on that |
788 | handle, just like DOSish perls. |
789 | |
790 | TCP/IP stacks are optional on VMS, so socket routines might not be |
791 | implemented. UDP sockets may not be supported. |
792 | |
793 | The value of C<$^O> on OpenVMS is "VMS". To determine the architecture |
794 | that you are running on without resorting to loading all of C<%Config> |
795 | you can examine the content of the C<@INC> array like so: |
796 | |
797 | if (grep(/VMS_AXP/, @INC)) { |
798 | print "I'm on Alpha!\n"; |
6ab3f9cb |
799 | |
e41182b5 |
800 | } elsif (grep(/VMS_VAX/, @INC)) { |
801 | print "I'm on VAX!\n"; |
6ab3f9cb |
802 | |
e41182b5 |
803 | } else { |
804 | print "I'm not so sure about where $^O is...\n"; |
805 | } |
806 | |
b7df3edc |
807 | On VMS, perl determines the UTC offset from the C<SYS$TIMEZONE_DIFFERENTIAL> |
808 | logical name. Although the VMS epoch began at 17-NOV-1858 00:00:00.00, |
6ab3f9cb |
809 | calls to C<localtime> are adjusted to count offsets from |
b7df3edc |
810 | 01-JAN-1970 00:00:00.00, just like Unix. |
6ab3f9cb |
811 | |
e41182b5 |
812 | Also see: |
813 | |
814 | =over 4 |
815 | |
816 | =item L<perlvms.pod> |
817 | |
6ab3f9cb |
818 | =item vmsperl list, C<majordomo@perl.org> |
e41182b5 |
819 | |
6ab3f9cb |
820 | Put the words C<subscribe vmsperl> in message body. |
e41182b5 |
821 | |
822 | =item vmsperl on the web, C<http://www.sidhe.org/vmsperl/index.html> |
823 | |
824 | =back |
825 | |
495c5fdc |
826 | =head2 VOS |
827 | |
828 | Perl on VOS is discussed in F<README.vos> in the perl distribution. |
b7df3edc |
829 | Perl on VOS can accept either VOS- or Unix-style file |
495c5fdc |
830 | specifications as in either of the following: |
831 | |
832 | $ perl -ne "print if /perl_setup/i" >system>notices |
833 | $ perl -ne "print if /perl_setup/i" /system/notices |
834 | |
835 | or even a mixture of both as in: |
836 | |
837 | $ perl -ne "print if /perl_setup/i" >system/notices |
838 | |
b7df3edc |
839 | Even though VOS allows the slash character to appear in object |
495c5fdc |
840 | names, because the VOS port of Perl interprets it as a pathname |
841 | delimiting character, VOS files, directories, or links whose names |
842 | contain a slash character cannot be processed. Such files must be |
843 | renamed before they can be processed by Perl. |
844 | |
2ee0eb3c |
845 | The following C functions are unimplemented on VOS, and any attempt by |
495c5fdc |
846 | Perl to use them will result in a fatal error message and an immediate |
2ee0eb3c |
847 | exit from Perl: dup, do_aspawn, do_spawn, fork, waitpid. Once these |
848 | functions become available in the VOS POSIX.1 implementation, you can |
849 | either recompile and rebind Perl, or you can download a newer port from |
850 | ftp.stratus.com. |
495c5fdc |
851 | |
852 | The value of C<$^O> on VOS is "VOS". To determine the architecture that |
853 | you are running on without resorting to loading all of C<%Config> you |
854 | can examine the content of the C<@INC> array like so: |
855 | |
856 | if (grep(/VOS/, @INC)) { |
857 | print "I'm on a Stratus box!\n"; |
858 | } else { |
859 | print "I'm not on a Stratus box!\n"; |
860 | die; |
861 | } |
862 | |
863 | if (grep(/860/, @INC)) { |
864 | print "This box is a Stratus XA/R!\n"; |
6ab3f9cb |
865 | |
495c5fdc |
866 | } elsif (grep(/7100/, @INC)) { |
867 | print "This box is a Stratus HP 7100 or 8000!\n"; |
6ab3f9cb |
868 | |
495c5fdc |
869 | } elsif (grep(/8000/, @INC)) { |
870 | print "This box is a Stratus HP 8000!\n"; |
6ab3f9cb |
871 | |
495c5fdc |
872 | } else { |
873 | print "This box is a Stratus 68K...\n"; |
874 | } |
875 | |
876 | Also see: |
877 | |
878 | =over 4 |
879 | |
880 | =item L<README.vos> |
881 | |
882 | =item VOS mailing list |
883 | |
884 | There is no specific mailing list for Perl on VOS. You can post |
885 | comments to the comp.sys.stratus newsgroup, or subscribe to the general |
886 | Stratus mailing list. Send a letter with "Subscribe Info-Stratus" in |
887 | the message body to majordomo@list.stratagy.com. |
888 | |
889 | =item VOS Perl on the web at C<http://ftp.stratus.com/pub/vos/vos.html> |
890 | |
891 | =back |
892 | |
e41182b5 |
893 | =head2 EBCDIC Platforms |
894 | |
895 | Recent versions of Perl have been ported to platforms such as OS/400 on |
7c5ffed3 |
896 | AS/400 minicomputers as well as OS/390 & VM/ESA for IBM Mainframes. Such |
897 | computers use EBCDIC character sets internally (usually Character Code |
b7df3edc |
898 | Set ID 00819 for OS/400 and IBM-1047 for OS/390 & VM/ESA). On |
7c5ffed3 |
899 | the mainframe perl currently works under the "Unix system services |
900 | for OS/390" (formerly known as OpenEdition) and VM/ESA OpenEdition. |
e41182b5 |
901 | |
7c5ffed3 |
902 | As of R2.5 of USS for OS/390 and Version 2.3 of VM/ESA these Unix |
903 | sub-systems do not support the C<#!> shebang trick for script invocation. |
904 | Hence, on OS/390 and VM/ESA perl scripts can be executed with a header |
905 | similar to the following simple script: |
e41182b5 |
906 | |
907 | : # use perl |
908 | eval 'exec /usr/local/bin/perl -S $0 ${1+"$@"}' |
909 | if 0; |
910 | #!/usr/local/bin/perl # just a comment really |
911 | |
912 | print "Hello from perl!\n"; |
913 | |
b7df3edc |
914 | On the AS/400, if PERL5 is in your library list, you may need |
6ab3f9cb |
915 | to wrap your perl scripts in a CL procedure to invoke them like so: |
916 | |
917 | BEGIN |
918 | CALL PGM(PERL5/PERL) PARM('/QOpenSys/hello.pl') |
919 | ENDPGM |
920 | |
921 | This will invoke the perl script F<hello.pl> in the root of the |
922 | QOpenSys file system. On the AS/400 calls to C<system> or backticks |
923 | must use CL syntax. |
924 | |
e41182b5 |
925 | On these platforms, bear in mind that the EBCDIC character set may have |
0a47030a |
926 | an effect on what happens with some perl functions (such as C<chr>, |
927 | C<pack>, C<print>, C<printf>, C<ord>, C<sort>, C<sprintf>, C<unpack>), as |
928 | well as bit-fiddling with ASCII constants using operators like C<^>, C<&> |
929 | and C<|>, not to mention dealing with socket interfaces to ASCII computers |
6ab3f9cb |
930 | (see L<"Newlines">). |
e41182b5 |
931 | |
b7df3edc |
932 | Fortunately, most web servers for the mainframe will correctly |
933 | translate the C<\n> in the following statement to its ASCII equivalent |
934 | (C<\r> is the same under both Unix and OS/390 & VM/ESA): |
e41182b5 |
935 | |
936 | print "Content-type: text/html\r\n\r\n"; |
937 | |
938 | The value of C<$^O> on OS/390 is "os390". |
939 | |
7c5ffed3 |
940 | The value of C<$^O> on VM/ESA is "vmesa". |
3c075c7d |
941 | |
e41182b5 |
942 | Some simple tricks for determining if you are running on an EBCDIC |
943 | platform could include any of the following (perhaps all): |
944 | |
945 | if ("\t" eq "\05") { print "EBCDIC may be spoken here!\n"; } |
946 | |
947 | if (ord('A') == 193) { print "EBCDIC may be spoken here!\n"; } |
948 | |
949 | if (chr(169) eq 'z') { print "EBCDIC may be spoken here!\n"; } |
950 | |
b7df3edc |
951 | One thing you may not want to rely on is the EBCDIC encoding |
0a47030a |
952 | of punctuation characters since these may differ from code page to code |
953 | page (and once your module or script is rumoured to work with EBCDIC, |
954 | folks will want it to work with all EBCDIC character sets). |
e41182b5 |
955 | |
956 | Also see: |
957 | |
958 | =over 4 |
959 | |
960 | =item perl-mvs list |
961 | |
962 | The perl-mvs@perl.org list is for discussion of porting issues as well as |
963 | general usage issues for all EBCDIC Perls. Send a message body of |
964 | "subscribe perl-mvs" to majordomo@perl.org. |
965 | |
0a47030a |
966 | =item AS/400 Perl information at C<http://as400.rochester.ibm.com/> |
e41182b5 |
967 | |
968 | =back |
969 | |
b8099c3d |
970 | =head2 Acorn RISC OS |
971 | |
b7df3edc |
972 | Because Acorns use ASCII with newlines (C<\n>) in text files as C<\012> like |
973 | Unix, and because Unix filename emulation is turned on by default, |
974 | most simple scripts will probably work "out of the box". The native |
6ab3f9cb |
975 | filesystem is modular, and individual filesystems are free to be |
0a47030a |
976 | case-sensitive or insensitive, and are usually case-preserving. Some |
b7df3edc |
977 | native filesystems have name length limits, which file and directory |
6ab3f9cb |
978 | names are silently truncated to fit. Scripts should be aware that the |
979 | standard filesystem currently has a name length limit of B<10> |
980 | characters, with up to 77 items in a directory, but other filesystems |
0a47030a |
981 | may not impose such limitations. |
b8099c3d |
982 | |
983 | Native filenames are of the form |
984 | |
6ab3f9cb |
985 | Filesystem#Special_Field::DiskName.$.Directory.Directory.File |
dd9f0070 |
986 | |
b8099c3d |
987 | where |
988 | |
989 | Special_Field is not usually present, but may contain . and $ . |
990 | Filesystem =~ m|[A-Za-z0-9_]| |
991 | DsicName =~ m|[A-Za-z0-9_/]| |
992 | $ represents the root directory |
993 | . is the path separator |
994 | @ is the current directory (per filesystem but machine global) |
995 | ^ is the parent directory |
996 | Directory and File =~ m|[^\0- "\.\$\%\&:\@\\^\|\177]+| |
997 | |
998 | The default filename translation is roughly C<tr|/.|./|;> |
999 | |
6ab3f9cb |
1000 | Note that C<"ADFS::HardDisk.$.File" ne 'ADFS::HardDisk.$.File'> and that |
0a47030a |
1001 | the second stage of C<$> interpolation in regular expressions will fall |
1002 | foul of the C<$.> if scripts are not careful. |
1003 | |
1004 | Logical paths specified by system variables containing comma-separated |
b7df3edc |
1005 | search lists are also allowed; hence C<System:Modules> is a valid |
0a47030a |
1006 | filename, and the filesystem will prefix C<Modules> with each section of |
6ab3f9cb |
1007 | C<System$Path> until a name is made that points to an object on disk. |
b7df3edc |
1008 | Writing to a new file C<System:Modules> would be allowed only if |
0a47030a |
1009 | C<System$Path> contains a single item list. The filesystem will also |
1010 | expand system variables in filenames if enclosed in angle brackets, so |
1011 | C<E<lt>System$DirE<gt>.Modules> would look for the file |
1012 | S<C<$ENV{'System$Dir'} . 'Modules'>>. The obvious implication of this is |
3c075c7d |
1013 | that B<fully qualified filenames can start with C<E<lt>E<gt>>> and should |
0a47030a |
1014 | be protected when C<open> is used for input. |
b8099c3d |
1015 | |
1016 | Because C<.> was in use as a directory separator and filenames could not |
1017 | be assumed to be unique after 10 characters, Acorn implemented the C |
1018 | compiler to strip the trailing C<.c> C<.h> C<.s> and C<.o> suffix from |
1019 | filenames specified in source code and store the respective files in |
b7df3edc |
1020 | subdirectories named after the suffix. Hence files are translated: |
b8099c3d |
1021 | |
1022 | foo.h h.foo |
1023 | C:foo.h C:h.foo (logical path variable) |
1024 | sys/os.h sys.h.os (C compiler groks Unix-speak) |
1025 | 10charname.c c.10charname |
1026 | 10charname.o o.10charname |
1027 | 11charname_.c c.11charname (assuming filesystem truncates at 10) |
1028 | |
1029 | The Unix emulation library's translation of filenames to native assumes |
b7df3edc |
1030 | that this sort of translation is required, and it allows a user-defined list |
1031 | of known suffixes that it will transpose in this fashion. This may |
1032 | seem transparent, but consider that with these rules C<foo/bar/baz.h> |
0a47030a |
1033 | and C<foo/bar/h/baz> both map to C<foo.bar.h.baz>, and that C<readdir> and |
1034 | C<glob> cannot and do not attempt to emulate the reverse mapping. Other |
6ab3f9cb |
1035 | C<.>'s in filenames are translated to C</>. |
0a47030a |
1036 | |
b7df3edc |
1037 | As implied above, the environment accessed through C<%ENV> is global, and |
0a47030a |
1038 | the convention is that program specific environment variables are of the |
6ab3f9cb |
1039 | form C<Program$Name>. Each filesystem maintains a current directory, |
1040 | and the current filesystem's current directory is the B<global> current |
b7df3edc |
1041 | directory. Consequently, sociable programs don't change the current |
1042 | directory but rely on full pathnames, and programs (and Makefiles) cannot |
0a47030a |
1043 | assume that they can spawn a child process which can change the current |
1044 | directory without affecting its parent (and everyone else for that |
1045 | matter). |
1046 | |
b7df3edc |
1047 | Because native operating system filehandles are global and are currently |
1048 | allocated down from 255, with 0 being a reserved value, the Unix emulation |
0a47030a |
1049 | library emulates Unix filehandles. Consequently, you can't rely on |
1050 | passing C<STDIN>, C<STDOUT>, or C<STDERR> to your children. |
1051 | |
1052 | The desire of users to express filenames of the form |
1053 | C<E<lt>Foo$DirE<gt>.Bar> on the command line unquoted causes problems, |
1054 | too: C<``> command output capture has to perform a guessing game. It |
1055 | assumes that a string C<E<lt>[^E<lt>E<gt>]+\$[^E<lt>E<gt>]E<gt>> is a |
1056 | reference to an environment variable, whereas anything else involving |
1057 | C<E<lt>> or C<E<gt>> is redirection, and generally manages to be 99% |
1058 | right. Of course, the problem remains that scripts cannot rely on any |
1059 | Unix tools being available, or that any tools found have Unix-like command |
1060 | line arguments. |
1061 | |
b7df3edc |
1062 | Extensions and XS are, in theory, buildable by anyone using free |
1063 | tools. In practice, many don't, as users of the Acorn platform are |
1064 | used to binary distributions. MakeMaker does run, but no available |
1065 | make currently copes with MakeMaker's makefiles; even if and when |
1066 | this should be fixed, the lack of a Unix-like shell will cause |
1067 | problems with makefile rules, especially lines of the form C<cd |
1068 | sdbm && make all>, and anything using quoting. |
b8099c3d |
1069 | |
1070 | "S<RISC OS>" is the proper name for the operating system, but the value |
1071 | in C<$^O> is "riscos" (because we don't like shouting). |
1072 | |
e41182b5 |
1073 | =head2 Other perls |
1074 | |
b7df3edc |
1075 | Perl has been ported to many platforms that do not fit into any of |
1076 | the categories listed above. Some, such as AmigaOS, Atari MiNT, |
1077 | BeOS, HP MPE/iX, QNX, Plan 9, and VOS, have been well-integrated |
1078 | into the standard Perl source code kit. You may need to see the |
1079 | F<ports/> directory on CPAN for information, and possibly binaries, |
1080 | for the likes of: aos, Atari ST, lynxos, riscos, Novell Netware, |
1081 | Tandem Guardian, I<etc.> (Yes, we know that some of these OSes may |
1082 | fall under the Unix category, but we are not a standards body.) |
e41182b5 |
1083 | |
1084 | See also: |
1085 | |
1086 | =over 4 |
1087 | |
1088 | =item Atari, Guido Flohr's page C<http://stud.uni-sb.de/~gufl0000/> |
1089 | |
1090 | =item HP 300 MPE/iX C<http://www.cccd.edu/~markb/perlix.html> |
1091 | |
1092 | =item Novell Netware |
1093 | |
6ab3f9cb |
1094 | A free perl5-based PERL.NLM for Novell Netware is available in |
1095 | precompiled binary and source code form from C<http://www.novell.com/> |
1096 | as well as from CPAN. |
e41182b5 |
1097 | |
1098 | =back |
1099 | |
e41182b5 |
1100 | =head1 FUNCTION IMPLEMENTATIONS |
1101 | |
b7df3edc |
1102 | Listed below are functions that are either completely unimplemented |
1103 | or else have been implemented differently on various platforms. |
1104 | Following each description will be, in parentheses, a list of |
1105 | platforms that the description applies to. |
e41182b5 |
1106 | |
b7df3edc |
1107 | The list may well be incomplete, or even wrong in some places. When |
1108 | in doubt, consult the platform-specific README files in the Perl |
1109 | source distribution, and any other documentation resources accompanying |
1110 | a given port. |
e41182b5 |
1111 | |
0a47030a |
1112 | Be aware, moreover, that even among Unix-ish systems there are variations. |
e41182b5 |
1113 | |
b7df3edc |
1114 | For many functions, you can also query C<%Config>, exported by |
1115 | default from the Config module. For example, to check whether the |
1116 | platform has the C<lstat> call, check C<$Config{d_lstat}>. See |
1117 | L<Config> for a full description of available variables. |
e41182b5 |
1118 | |
1119 | =head2 Alphabetical Listing of Perl Functions |
1120 | |
1121 | =over 8 |
1122 | |
1123 | =item -X FILEHANDLE |
1124 | |
1125 | =item -X EXPR |
1126 | |
1127 | =item -X |
1128 | |
b7df3edc |
1129 | C<-r>, C<-w>, and C<-x> have a limited meaning only; directories |
e41182b5 |
1130 | and applications are executable, and there are no uid/gid |
b7df3edc |
1131 | considerations. C<-o> is not supported. (S<Mac OS>) |
e41182b5 |
1132 | |
b7df3edc |
1133 | C<-r>, C<-w>, C<-x>, and C<-o> tell whether the file is accessible, |
1134 | which may not reflect UIC-based file protections. (VMS) |
e41182b5 |
1135 | |
b8099c3d |
1136 | C<-s> returns the size of the data fork, not the total size of data fork |
1137 | plus resource fork. (S<Mac OS>). |
1138 | |
1139 | C<-s> by name on an open file will return the space reserved on disk, |
1140 | rather than the current extent. C<-s> on an open filehandle returns the |
b7df3edc |
1141 | current size. (S<RISC OS>) |
b8099c3d |
1142 | |
e41182b5 |
1143 | C<-R>, C<-W>, C<-X>, C<-O> are indistinguishable from C<-r>, C<-w>, |
b8099c3d |
1144 | C<-x>, C<-o>. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1145 | |
1146 | C<-b>, C<-c>, C<-k>, C<-g>, C<-p>, C<-u>, C<-A> are not implemented. |
1147 | (S<Mac OS>) |
1148 | |
1149 | C<-g>, C<-k>, C<-l>, C<-p>, C<-u>, C<-A> are not particularly meaningful. |
b8099c3d |
1150 | (Win32, VMS, S<RISC OS>) |
e41182b5 |
1151 | |
1152 | C<-d> is true if passed a device spec without an explicit directory. |
1153 | (VMS) |
1154 | |
1155 | C<-T> and C<-B> are implemented, but might misclassify Mac text files |
0a47030a |
1156 | with foreign characters; this is the case will all platforms, but may |
b7df3edc |
1157 | affect S<Mac OS> often. (S<Mac OS>) |
e41182b5 |
1158 | |
1159 | C<-x> (or C<-X>) determine if a file ends in one of the executable |
b7df3edc |
1160 | suffixes. C<-S> is meaningless. (Win32) |
e41182b5 |
1161 | |
b8099c3d |
1162 | C<-x> (or C<-X>) determine if a file has an executable file type. |
1163 | (S<RISC OS>) |
1164 | |
e41182b5 |
1165 | =item binmode FILEHANDLE |
1166 | |
b7df3edc |
1167 | Meaningless. (S<Mac OS>, S<RISC OS>) |
e41182b5 |
1168 | |
1169 | Reopens file and restores pointer; if function fails, underlying |
1170 | filehandle may be closed, or pointer may be in a different position. |
1171 | (VMS) |
1172 | |
1173 | The value returned by C<tell> may be affected after the call, and |
1174 | the filehandle may be flushed. (Win32) |
1175 | |
1176 | =item chmod LIST |
1177 | |
b7df3edc |
1178 | Only limited meaning. Disabling/enabling write permission is mapped to |
e41182b5 |
1179 | locking/unlocking the file. (S<Mac OS>) |
1180 | |
1181 | Only good for changing "owner" read-write access, "group", and "other" |
1182 | bits are meaningless. (Win32) |
1183 | |
b8099c3d |
1184 | Only good for changing "owner" and "other" read-write access. (S<RISC OS>) |
1185 | |
495c5fdc |
1186 | Access permissions are mapped onto VOS access-control list changes. (VOS) |
1187 | |
e41182b5 |
1188 | =item chown LIST |
1189 | |
495c5fdc |
1190 | Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>, VOS) |
e41182b5 |
1191 | |
1192 | Does nothing, but won't fail. (Win32) |
1193 | |
1194 | =item chroot FILENAME |
1195 | |
1196 | =item chroot |
1197 | |
7c5ffed3 |
1198 | Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>, VOS, VM/ESA) |
e41182b5 |
1199 | |
1200 | =item crypt PLAINTEXT,SALT |
1201 | |
1202 | May not be available if library or source was not provided when building |
b8099c3d |
1203 | perl. (Win32) |
e41182b5 |
1204 | |
495c5fdc |
1205 | Not implemented. (VOS) |
1206 | |
e41182b5 |
1207 | =item dbmclose HASH |
1208 | |
495c5fdc |
1209 | Not implemented. (VMS, Plan9, VOS) |
e41182b5 |
1210 | |
1211 | =item dbmopen HASH,DBNAME,MODE |
1212 | |
495c5fdc |
1213 | Not implemented. (VMS, Plan9, VOS) |
e41182b5 |
1214 | |
1215 | =item dump LABEL |
1216 | |
b8099c3d |
1217 | Not useful. (S<Mac OS>, S<RISC OS>) |
e41182b5 |
1218 | |
1219 | Not implemented. (Win32) |
1220 | |
b8099c3d |
1221 | Invokes VMS debugger. (VMS) |
e41182b5 |
1222 | |
1223 | =item exec LIST |
1224 | |
1225 | Not implemented. (S<Mac OS>) |
1226 | |
7c5ffed3 |
1227 | Implemented via Spawn. (VM/ESA) |
3c075c7d |
1228 | |
e41182b5 |
1229 | =item fcntl FILEHANDLE,FUNCTION,SCALAR |
1230 | |
1231 | Not implemented. (Win32, VMS) |
1232 | |
1233 | =item flock FILEHANDLE,OPERATION |
1234 | |
495c5fdc |
1235 | Not implemented (S<Mac OS>, VMS, S<RISC OS>, VOS). |
e41182b5 |
1236 | |
1237 | Available only on Windows NT (not on Windows 95). (Win32) |
1238 | |
1239 | =item fork |
1240 | |
7c5ffed3 |
1241 | Not implemented. (S<Mac OS>, Win32, AmigaOS, S<RISC OS>, VOS, VM/ESA) |
e41182b5 |
1242 | |
1243 | =item getlogin |
1244 | |
b8099c3d |
1245 | Not implemented. (S<Mac OS>, S<RISC OS>) |
e41182b5 |
1246 | |
1247 | =item getpgrp PID |
1248 | |
495c5fdc |
1249 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS) |
e41182b5 |
1250 | |
1251 | =item getppid |
1252 | |
b8099c3d |
1253 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1254 | |
1255 | =item getpriority WHICH,WHO |
1256 | |
7c5ffed3 |
1257 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA) |
e41182b5 |
1258 | |
1259 | =item getpwnam NAME |
1260 | |
1261 | Not implemented. (S<Mac OS>, Win32) |
1262 | |
b8099c3d |
1263 | Not useful. (S<RISC OS>) |
1264 | |
e41182b5 |
1265 | =item getgrnam NAME |
1266 | |
b8099c3d |
1267 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1268 | |
1269 | =item getnetbyname NAME |
1270 | |
1271 | Not implemented. (S<Mac OS>, Win32, Plan9) |
1272 | |
1273 | =item getpwuid UID |
1274 | |
1275 | Not implemented. (S<Mac OS>, Win32) |
1276 | |
b8099c3d |
1277 | Not useful. (S<RISC OS>) |
1278 | |
e41182b5 |
1279 | =item getgrgid GID |
1280 | |
b8099c3d |
1281 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1282 | |
1283 | =item getnetbyaddr ADDR,ADDRTYPE |
1284 | |
1285 | Not implemented. (S<Mac OS>, Win32, Plan9) |
1286 | |
1287 | =item getprotobynumber NUMBER |
1288 | |
1289 | Not implemented. (S<Mac OS>) |
1290 | |
1291 | =item getservbyport PORT,PROTO |
1292 | |
1293 | Not implemented. (S<Mac OS>) |
1294 | |
1295 | =item getpwent |
1296 | |
7c5ffed3 |
1297 | Not implemented. (S<Mac OS>, Win32, VM/ESA) |
e41182b5 |
1298 | |
1299 | =item getgrent |
1300 | |
7c5ffed3 |
1301 | Not implemented. (S<Mac OS>, Win32, VMS, VM/ESA) |
e41182b5 |
1302 | |
1303 | =item gethostent |
1304 | |
1305 | Not implemented. (S<Mac OS>, Win32) |
1306 | |
1307 | =item getnetent |
1308 | |
1309 | Not implemented. (S<Mac OS>, Win32, Plan9) |
1310 | |
1311 | =item getprotoent |
1312 | |
1313 | Not implemented. (S<Mac OS>, Win32, Plan9) |
1314 | |
1315 | =item getservent |
1316 | |
1317 | Not implemented. (Win32, Plan9) |
1318 | |
1319 | =item setpwent |
1320 | |
b8099c3d |
1321 | Not implemented. (S<Mac OS>, Win32, S<RISC OS>) |
e41182b5 |
1322 | |
1323 | =item setgrent |
1324 | |
b8099c3d |
1325 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1326 | |
1327 | =item sethostent STAYOPEN |
1328 | |
b8099c3d |
1329 | Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>) |
e41182b5 |
1330 | |
1331 | =item setnetent STAYOPEN |
1332 | |
b8099c3d |
1333 | Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>) |
e41182b5 |
1334 | |
1335 | =item setprotoent STAYOPEN |
1336 | |
b8099c3d |
1337 | Not implemented. (S<Mac OS>, Win32, Plan9, S<RISC OS>) |
e41182b5 |
1338 | |
1339 | =item setservent STAYOPEN |
1340 | |
b8099c3d |
1341 | Not implemented. (Plan9, Win32, S<RISC OS>) |
e41182b5 |
1342 | |
1343 | =item endpwent |
1344 | |
7c5ffed3 |
1345 | Not implemented. (S<Mac OS>, Win32, VM/ESA) |
e41182b5 |
1346 | |
1347 | =item endgrent |
1348 | |
7c5ffed3 |
1349 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VM/ESA) |
e41182b5 |
1350 | |
1351 | =item endhostent |
1352 | |
1353 | Not implemented. (S<Mac OS>, Win32) |
1354 | |
1355 | =item endnetent |
1356 | |
1357 | Not implemented. (S<Mac OS>, Win32, Plan9) |
1358 | |
1359 | =item endprotoent |
1360 | |
1361 | Not implemented. (S<Mac OS>, Win32, Plan9) |
1362 | |
1363 | =item endservent |
1364 | |
1365 | Not implemented. (Plan9, Win32) |
1366 | |
1367 | =item getsockopt SOCKET,LEVEL,OPTNAME |
1368 | |
1369 | Not implemented. (S<Mac OS>, Plan9) |
1370 | |
1371 | =item glob EXPR |
1372 | |
1373 | =item glob |
1374 | |
1375 | Globbing built-in, but only C<*> and C<?> metacharacters are supported. |
1376 | (S<Mac OS>) |
1377 | |
b7df3edc |
1378 | Features depend on external perlglob.exe or perlglob.bat. May be |
0a47030a |
1379 | overridden with something like File::DosGlob, which is recommended. |
1380 | (Win32) |
e41182b5 |
1381 | |
b8099c3d |
1382 | Globbing built-in, but only C<*> and C<?> metacharacters are supported. |
0a47030a |
1383 | Globbing relies on operating system calls, which may return filenames |
1384 | in any order. As most filesystems are case-insensitive, even "sorted" |
1385 | filenames will not be in case-sensitive order. (S<RISC OS>) |
b8099c3d |
1386 | |
e41182b5 |
1387 | =item ioctl FILEHANDLE,FUNCTION,SCALAR |
1388 | |
1389 | Not implemented. (VMS) |
1390 | |
1391 | Available only for socket handles, and it does what the ioctlsocket() call |
1392 | in the Winsock API does. (Win32) |
1393 | |
b8099c3d |
1394 | Available only for socket handles. (S<RISC OS>) |
1395 | |
e41182b5 |
1396 | =item kill LIST |
1397 | |
0a47030a |
1398 | Not implemented, hence not useful for taint checking. (S<Mac OS>, |
1399 | S<RISC OS>) |
e41182b5 |
1400 | |
0a47030a |
1401 | Available only for process handles returned by the C<system(1, ...)> |
1402 | method of spawning a process. (Win32) |
e41182b5 |
1403 | |
1404 | =item link OLDFILE,NEWFILE |
1405 | |
b8099c3d |
1406 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>) |
e41182b5 |
1407 | |
433acd8a |
1408 | Link count not updated because hard links are not quite that hard |
1409 | (They are sort of half-way between hard and soft links). (AmigaOS) |
1410 | |
e41182b5 |
1411 | =item lstat FILEHANDLE |
1412 | |
1413 | =item lstat EXPR |
1414 | |
1415 | =item lstat |
1416 | |
b8099c3d |
1417 | Not implemented. (VMS, S<RISC OS>) |
e41182b5 |
1418 | |
b8099c3d |
1419 | Return values may be bogus. (Win32) |
e41182b5 |
1420 | |
1421 | =item msgctl ID,CMD,ARG |
1422 | |
1423 | =item msgget KEY,FLAGS |
1424 | |
1425 | =item msgsnd ID,MSG,FLAGS |
1426 | |
1427 | =item msgrcv ID,VAR,SIZE,TYPE,FLAGS |
1428 | |
495c5fdc |
1429 | Not implemented. (S<Mac OS>, Win32, VMS, Plan9, S<RISC OS>, VOS) |
e41182b5 |
1430 | |
1431 | =item open FILEHANDLE,EXPR |
1432 | |
1433 | =item open FILEHANDLE |
1434 | |
b7df3edc |
1435 | The C<|> variants are supported only if ToolServer is installed. |
e41182b5 |
1436 | (S<Mac OS>) |
1437 | |
b8099c3d |
1438 | open to C<|-> and C<-|> are unsupported. (S<Mac OS>, Win32, S<RISC OS>) |
e41182b5 |
1439 | |
1440 | =item pipe READHANDLE,WRITEHANDLE |
1441 | |
1442 | Not implemented. (S<Mac OS>) |
1443 | |
433acd8a |
1444 | Very limited functionality. (MiNT) |
1445 | |
e41182b5 |
1446 | =item readlink EXPR |
1447 | |
1448 | =item readlink |
1449 | |
b8099c3d |
1450 | Not implemented. (Win32, VMS, S<RISC OS>) |
e41182b5 |
1451 | |
1452 | =item select RBITS,WBITS,EBITS,TIMEOUT |
1453 | |
1454 | Only implemented on sockets. (Win32) |
1455 | |
b8099c3d |
1456 | Only reliable on sockets. (S<RISC OS>) |
1457 | |
e41182b5 |
1458 | =item semctl ID,SEMNUM,CMD,ARG |
1459 | |
1460 | =item semget KEY,NSEMS,FLAGS |
1461 | |
1462 | =item semop KEY,OPSTRING |
1463 | |
495c5fdc |
1464 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS) |
e41182b5 |
1465 | |
1466 | =item setpgrp PID,PGRP |
1467 | |
495c5fdc |
1468 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS) |
e41182b5 |
1469 | |
1470 | =item setpriority WHICH,WHO,PRIORITY |
1471 | |
495c5fdc |
1472 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS) |
e41182b5 |
1473 | |
1474 | =item setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL |
1475 | |
1476 | Not implemented. (S<Mac OS>, Plan9) |
1477 | |
1478 | =item shmctl ID,CMD,ARG |
1479 | |
1480 | =item shmget KEY,SIZE,FLAGS |
1481 | |
1482 | =item shmread ID,VAR,POS,SIZE |
1483 | |
1484 | =item shmwrite ID,STRING,POS,SIZE |
1485 | |
495c5fdc |
1486 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS) |
e41182b5 |
1487 | |
1488 | =item socketpair SOCKET1,SOCKET2,DOMAIN,TYPE,PROTOCOL |
1489 | |
7c5ffed3 |
1490 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA) |
e41182b5 |
1491 | |
1492 | =item stat FILEHANDLE |
1493 | |
1494 | =item stat EXPR |
1495 | |
1496 | =item stat |
1497 | |
1498 | mtime and atime are the same thing, and ctime is creation time instead of |
1499 | inode change time. (S<Mac OS>) |
1500 | |
1501 | device and inode are not meaningful. (Win32) |
1502 | |
1503 | device and inode are not necessarily reliable. (VMS) |
1504 | |
b8099c3d |
1505 | mtime, atime and ctime all return the last modification time. Device and |
1506 | inode are not necessarily reliable. (S<RISC OS>) |
1507 | |
e41182b5 |
1508 | =item symlink OLDFILE,NEWFILE |
1509 | |
b8099c3d |
1510 | Not implemented. (Win32, VMS, S<RISC OS>) |
e41182b5 |
1511 | |
1512 | =item syscall LIST |
1513 | |
7c5ffed3 |
1514 | Not implemented. (S<Mac OS>, Win32, VMS, S<RISC OS>, VOS, VM/ESA) |
e41182b5 |
1515 | |
f34d0673 |
1516 | =item sysopen FILEHANDLE,FILENAME,MODE,PERMS |
1517 | |
dd9f0070 |
1518 | The traditional "0", "1", and "2" MODEs are implemented with different |
322422de |
1519 | numeric values on some systems. The flags exported by C<Fcntl> |
1520 | (O_RDONLY, O_WRONLY, O_RDWR) should work everywhere though. (S<Mac |
7c5ffed3 |
1521 | OS>, OS/390, VM/ESA) |
f34d0673 |
1522 | |
e41182b5 |
1523 | =item system LIST |
1524 | |
1525 | Only implemented if ToolServer is installed. (S<Mac OS>) |
1526 | |
1527 | As an optimization, may not call the command shell specified in |
b7df3edc |
1528 | C<$ENV{PERL5SHELL}>. C<system(1, @args)> spawns an external |
e41182b5 |
1529 | process and immediately returns its process designator, without |
1530 | waiting for it to terminate. Return value may be used subsequently |
1531 | in C<wait> or C<waitpid>. (Win32) |
1532 | |
b8099c3d |
1533 | There is no shell to process metacharacters, and the native standard is |
1534 | to pass a command line terminated by "\n" "\r" or "\0" to the spawned |
1535 | program. Redirection such as C<E<gt> foo> is performed (if at all) by |
1536 | the run time library of the spawned program. C<system> I<list> will call |
1537 | the Unix emulation library's C<exec> emulation, which attempts to provide |
1538 | emulation of the stdin, stdout, stderr in force in the parent, providing |
1539 | the child program uses a compatible version of the emulation library. |
1540 | I<scalar> will call the native command line direct and no such emulation |
1541 | of a child Unix program will exists. Mileage B<will> vary. (S<RISC OS>) |
1542 | |
433acd8a |
1543 | Far from being POSIX compliant. Because there may be no underlying |
1544 | /bin/sh tries to work around the problem by forking and execing the |
9b63e9ec |
1545 | first token in its argument string. Handles basic redirection |
1546 | ("E<lt>" or "E<gt>") on its own behalf. (MiNT) |
433acd8a |
1547 | |
e41182b5 |
1548 | =item times |
1549 | |
1550 | Only the first entry returned is nonzero. (S<Mac OS>) |
1551 | |
1552 | "cumulative" times will be bogus. On anything other than Windows NT, |
1553 | "system" time will be bogus, and "user" time is actually the time |
1554 | returned by the clock() function in the C runtime library. (Win32) |
1555 | |
b8099c3d |
1556 | Not useful. (S<RISC OS>) |
1557 | |
e41182b5 |
1558 | =item truncate FILEHANDLE,LENGTH |
1559 | |
1560 | =item truncate EXPR,LENGTH |
1561 | |
1562 | Not implemented. (VMS) |
1563 | |
495c5fdc |
1564 | Truncation to zero-length only. (VOS) |
1565 | |
4cfdb94f |
1566 | If a FILEHANDLE is supplied, it must be writable and opened in append |
1567 | mode (i.e., use C<open(FH, '>>filename')> |
1568 | or C<sysopen(FH,...,O_APPEND|O_RDWR)>. If a filename is supplied, it |
1569 | should not be held open elsewhere. (Win32) |
1570 | |
e41182b5 |
1571 | =item umask EXPR |
1572 | |
1573 | =item umask |
1574 | |
1575 | Returns undef where unavailable, as of version 5.005. |
1576 | |
b7df3edc |
1577 | C<umask> works but the correct permissions are set only when the file |
1578 | is finally closed. (AmigaOS) |
433acd8a |
1579 | |
e41182b5 |
1580 | =item utime LIST |
1581 | |
b8099c3d |
1582 | Only the modification time is updated. (S<Mac OS>, VMS, S<RISC OS>) |
e41182b5 |
1583 | |
322422de |
1584 | May not behave as expected. Behavior depends on the C runtime |
1585 | library's implementation of utime(), and the filesystem being |
1586 | used. The FAT filesystem typically does not support an "access |
1587 | time" field, and it may limit timestamps to a granularity of |
1588 | two seconds. (Win32) |
e41182b5 |
1589 | |
1590 | =item wait |
1591 | |
1592 | =item waitpid PID,FLAGS |
1593 | |
495c5fdc |
1594 | Not implemented. (S<Mac OS>, VOS) |
e41182b5 |
1595 | |
1596 | Can only be applied to process handles returned for processes spawned |
1597 | using C<system(1, ...)>. (Win32) |
1598 | |
b8099c3d |
1599 | Not useful. (S<RISC OS>) |
1600 | |
e41182b5 |
1601 | =back |
1602 | |
b8099c3d |
1603 | =head1 CHANGES |
1604 | |
1605 | =over 4 |
1606 | |
b7df3edc |
1607 | =item v1.43, 24 May 1999 |
1608 | |
1609 | Added a lot of cleaning up from Tom Christiansen. |
1610 | |
19799a22 |
1611 | =item v1.42, 22 May 1999 |
b7df3edc |
1612 | |
19799a22 |
1613 | Added notes about tests, sprintf/printf, and epoch offsets. |
b7df3edc |
1614 | |
6ab3f9cb |
1615 | =item v1.41, 19 May 1999 |
1616 | |
1617 | Lots more little changes to formatting and content. |
1618 | |
1619 | Added a bunch of <$^O> and related values |
1620 | for various platforms; fixed mail and web addresses, and added |
1621 | and changed miscellaneous notes. (Peter Prymmer) |
1622 | |
1623 | =item v1.40, 11 April 1999 |
1624 | |
1625 | Miscellaneous changes. |
1626 | |
1627 | =item v1.39, 11 February 1999 |
2ee0eb3c |
1628 | |
1629 | Changes from Jarkko and EMX URL fixes Michael Schwern. Additional |
1630 | note about newlines added. |
1631 | |
9b63e9ec |
1632 | =item v1.38, 31 December 1998 |
1633 | |
1634 | More changes from Jarkko. |
1635 | |
3c075c7d |
1636 | =item v1.37, 19 December 1998 |
1637 | |
1638 | More minor changes. Merge two separate version 1.35 documents. |
1639 | |
1640 | =item v1.36, 9 September 1998 |
1641 | |
1642 | Updated for Stratus VOS. Also known as version 1.35. |
1643 | |
1644 | =item v1.35, 13 August 1998 |
495c5fdc |
1645 | |
3c075c7d |
1646 | Integrate more minor changes, plus addition of new sections under |
1647 | L<"ISSUES">: L<"Numbers endianness and Width">, |
1648 | L<"Character sets and character encoding">, |
1649 | L<"Internationalisation">. |
495c5fdc |
1650 | |
3c075c7d |
1651 | =item v1.33, 06 August 1998 |
0a47030a |
1652 | |
1653 | Integrate more minor changes. |
1654 | |
3c075c7d |
1655 | =item v1.32, 05 August 1998 |
dd9f0070 |
1656 | |
1657 | Integrate more minor changes. |
1658 | |
3c075c7d |
1659 | =item v1.30, 03 August 1998 |
b8099c3d |
1660 | |
1661 | Major update for RISC OS, other minor changes. |
1662 | |
3c075c7d |
1663 | =item v1.23, 10 July 1998 |
b8099c3d |
1664 | |
1665 | First public release with perl5.005. |
1666 | |
1667 | =back |
e41182b5 |
1668 | |
1669 | =head1 AUTHORS / CONTRIBUTORS |
1670 | |
dd9f0070 |
1671 | Abigail E<lt>abigail@fnx.comE<gt>, |
bd3fa61c |
1672 | Charles Bailey E<lt>bailey@newman.upenn.eduE<gt>, |
dd9f0070 |
1673 | Graham Barr E<lt>gbarr@pobox.comE<gt>, |
e41182b5 |
1674 | Tom Christiansen E<lt>tchrist@perl.comE<gt>, |
dd9f0070 |
1675 | Nicholas Clark E<lt>Nicholas.Clark@liverpool.ac.ukE<gt>, |
1676 | Andy Dougherty E<lt>doughera@lafcol.lafayette.eduE<gt>, |
1677 | Dominic Dunlop E<lt>domo@vo.luE<gt>, |
7c5ffed3 |
1678 | Neale Ferguson E<lt>neale@mailbox.tabnsw.com.auE<gt> |
495c5fdc |
1679 | Paul Green E<lt>Paul_Green@stratus.comE<gt>, |
dd9f0070 |
1680 | M.J.T. Guy E<lt>mjtg@cus.cam.ac.ukE<gt>, |
7c5ffed3 |
1681 | Jarkko Hietaniemi E<lt>jhi@iki.fi<gt>, |
dd9f0070 |
1682 | Luther Huffman E<lt>lutherh@stratcom.comE<gt>, |
1683 | Nick Ing-Simmons E<lt>nick@ni-s.u-net.comE<gt>, |
322422de |
1684 | Andreas J. KE<ouml>nig E<lt>koenig@kulturbox.deE<gt>, |
3c075c7d |
1685 | Markus Laker E<lt>mlaker@contax.co.ukE<gt>, |
dd9f0070 |
1686 | Andrew M. Langmead E<lt>aml@world.std.comE<gt>, |
19799a22 |
1687 | Larry Moore E<lt>ljmoore@freespace.netE<gt>, |
e41182b5 |
1688 | Paul Moore E<lt>Paul.Moore@uk.origin-it.comE<gt>, |
dd9f0070 |
1689 | Chris Nandor E<lt>pudge@pobox.comE<gt>, |
322422de |
1690 | Matthias Neeracher E<lt>neeri@iis.ee.ethz.chE<gt>, |
e41182b5 |
1691 | Gary Ng E<lt>71564.1743@CompuServe.COME<gt>, |
e41182b5 |
1692 | Tom Phoenix E<lt>rootbeer@teleport.comE<gt>, |
dd9f0070 |
1693 | Peter Prymmer E<lt>pvhp@forte.comE<gt>, |
322422de |
1694 | Hugo van der Sanden E<lt>hv@crypt0.demon.co.ukE<gt>, |
dd9f0070 |
1695 | Gurusamy Sarathy E<lt>gsar@umich.eduE<gt>, |
1696 | Paul J. Schinder E<lt>schinder@pobox.comE<gt>, |
2ee0eb3c |
1697 | Michael G Schwern E<lt>schwern@pobox.comE<gt>, |
e41182b5 |
1698 | Dan Sugalski E<lt>sugalskd@ous.eduE<gt>, |
dd9f0070 |
1699 | Nathan Torkington E<lt>gnat@frii.comE<gt>. |
e41182b5 |
1700 | |
3c075c7d |
1701 | This document is maintained by Chris Nandor |
1702 | E<lt>pudge@pobox.comE<gt>. |
e41182b5 |
1703 | |
1704 | =head1 VERSION |
1705 | |
b7df3edc |
1706 | Version 1.43, last modified 24 May 1999 |