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a0d0e21e LW |
1 | =head1 NAME |
2 | ||
3 | perl - Practical Extraction and Report Language | |
4 | ||
5 | =head1 SYNOPSIS | |
6 | ||
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7 | B<perl> S<[ B<-sTuU> ]> S<[ B<-hv> ] [ B<-V>[:I<configvar>] ]> |
8 | S<[ B<-cw> ] [ B<-d>[:I<debugger>] ] [ B<-D>[I<number/list>] ]> | |
9 | S<[ B<-pna> ] [ B<-F>I<pattern> ] [ B<-l>[I<octal>] ] [ B<-0>[I<octal>] ]> | |
10 | S<[ B<-I>I<dir> ] [ B<-m>[B<->]I<module> ] [ B<-M>[B<->]I<'module...'> ]> | |
11 | S<[ B<-P> ]> S<[ B<-S> ]> S<[ B<-x>[I<dir>] ]> | |
12 | S<[ B<-i>[I<extension>] ]> S<[ B<-e> I<'command'> ] | |
13 | [ B<--> ] [ I<programfile> ] [ I<argument> ]...> | |
c07a80fd | 14 | |
ff45a9ac | 15 | For ease of access, the Perl manual has been split up into several sections: |
a0d0e21e | 16 | |
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17 | perl Perl overview (this section) |
18 | perldelta Perl changes since previous version | |
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19 | perl5005delta Perl changes in version 5.005 |
20 | perl5004delta Perl changes in version 5.004 | |
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21 | perlfaq Perl frequently asked questions |
22 | perltoc Perl documentation table of contents | |
760ac839 | 23 | |
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24 | perldata Perl data structures |
25 | perlsyn Perl syntax | |
26 | perlop Perl operators and precedence | |
27 | perlre Perl regular expressions | |
28 | perlrun Perl execution and options | |
29 | perlfunc Perl builtin functions | |
2605996a | 30 | perlopentut Perl open() tutorial |
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31 | perlvar Perl predefined variables |
32 | perlsub Perl subroutines | |
33 | perlmod Perl modules: how they work | |
34 | perlmodlib Perl modules: how to write and use | |
35 | perlmodinstall Perl modules: how to install from CPAN | |
2e1d04bc JH |
36 | perlnewpod Perl modules: preparing a new module for distribution |
37 | ||
fb9cefb4 | 38 | perlform Perl formats |
49877630 | 39 | perlunicode Perl unicode support |
fb9cefb4 | 40 | perllocale Perl locale support |
760ac839 | 41 | |
a1e2a320 | 42 | perlreftut Perl references short introduction |
19799a22 | 43 | perlref Perl references, the rest of the story |
fb9cefb4 | 44 | perldsc Perl data structures intro |
19799a22 | 45 | perllol Perl data structures: arrays of arrays |
694468e3 | 46 | perlboot Perl OO tutorial for beginners |
19799a22 GS |
47 | perltoot Perl OO tutorial, part 1 |
48 | perltootc Perl OO tutorial, part 2 | |
fb9cefb4 GS |
49 | perlobj Perl objects |
50 | perltie Perl objects hidden behind simple variables | |
51 | perlbot Perl OO tricks and examples | |
52 | perlipc Perl interprocess communication | |
7766f137 | 53 | perlfork Perl fork() information |
2605996a | 54 | perlthrtut Perl threads tutorial |
49877630 | 55 | perllexwarn Perl warnings and their control |
c93fa817 | 56 | perlfilter Perl source filters |
49877630 | 57 | perldbmfilter Perl DBM filters |
760ac839 | 58 | |
54a137f5 | 59 | perlcompile Perl compiler suite intro |
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60 | perldebug Perl debugging |
61 | perldiag Perl diagnostic messages | |
ac65edd0 | 62 | perlnumber Perl number semantics |
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63 | perlsec Perl security |
64 | perltrap Perl traps for the unwary | |
65 | perlport Perl portability guide | |
66 | perlstyle Perl style guide | |
760ac839 | 67 | |
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68 | perlpod Perl plain old documentation |
69 | perlbook Perl book information | |
760ac839 | 70 | |
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71 | perlembed Perl ways to embed perl in your C or C++ application |
72 | perlapio Perl internal IO abstraction interface | |
055fd3a9 | 73 | perldebguts Perl debugging guts and tips |
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74 | perlxs Perl XS application programming interface |
75 | perlxstut Perl XS tutorial | |
76 | perlguts Perl internal functions for those doing extensions | |
77 | perlcall Perl calling conventions from C | |
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78 | perlapi Perl API listing (autogenerated) |
79 | perlintern Perl internal functions (autogenerated) | |
a0d0e21e | 80 | |
e50bb9a1 | 81 | perltodo Perl things to do |
e8cd7eae | 82 | perlhack Perl hackers guide |
fb9cefb4 | 83 | perlhist Perl history records |
d516a115 | 84 | |
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85 | perlamiga Perl notes for Amiga |
86 | perlcygwin Perl notes for Cygwin | |
87 | perldos Perl notes for DOS | |
88 | perlhpux Perl notes for HP-UX | |
da369004 | 89 | perlmachten Perl notes for Power MachTen |
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90 | perlos2 Perl notes for OS/2 |
91 | perlos390 Perl notes for OS/390 | |
92 | perlvms Perl notes for VMS | |
93 | perlwin32 Perl notes for Windows | |
94 | ||
a0d0e21e LW |
95 | (If you're intending to read these straight through for the first time, |
96 | the suggested order will tend to reduce the number of forward references.) | |
97 | ||
19799a22 | 98 | By default, the manpages listed above are installed in the |
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99 | F</usr/local/man/> directory. |
100 | ||
101 | Extensive additional documentation for Perl modules is available. The | |
102 | default configuration for perl will place this additional documentation | |
103 | in the F</usr/local/lib/perl5/man> directory (or else in the F<man> | |
104 | subdirectory of the Perl library directory). Some of this additional | |
105 | documentation is distributed standard with Perl, but you'll also find | |
106 | documentation for third-party modules there. | |
107 | ||
108 | You should be able to view Perl's documentation with your man(1) | |
109 | program by including the proper directories in the appropriate start-up | |
110 | files, or in the MANPATH environment variable. To find out where the | |
111 | configuration has installed the manpages, type: | |
16d20bd9 | 112 | |
760ac839 | 113 | perl -V:man.dir |
16d20bd9 | 114 | |
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115 | If the directories have a common stem, such as F</usr/local/man/man1> |
116 | and F</usr/local/man/man3>, you need only to add that stem | |
117 | (F</usr/local/man>) to your man(1) configuration files or your MANPATH | |
118 | environment variable. If they do not share a stem, you'll have to add | |
119 | both stems. | |
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120 | |
121 | If that doesn't work for some reason, you can still use the | |
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122 | supplied F<perldoc> script to view module information. You might |
123 | also look into getting a replacement man program. | |
16d20bd9 | 124 | |
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125 | If something strange has gone wrong with your program and you're not |
126 | sure where you should look for help, try the B<-w> switch first. It | |
127 | will often point out exactly where the trouble is. | |
128 | ||
129 | =head1 DESCRIPTION | |
130 | ||
5f05dabc | 131 | Perl is a language optimized for scanning arbitrary |
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132 | text files, extracting information from those text files, and printing |
133 | reports based on that information. It's also a good language for many | |
134 | system management tasks. The language is intended to be practical | |
135 | (easy to use, efficient, complete) rather than beautiful (tiny, | |
94d58c47 | 136 | elegant, minimal). |
137 | ||
aa689395 | 138 | Perl combines (in the author's opinion, anyway) some of the best |
139 | features of C, B<sed>, B<awk>, and B<sh>, so people familiar with | |
140 | those languages should have little difficulty with it. (Language | |
141 | historians will also note some vestiges of B<csh>, Pascal, and even | |
14218588 | 142 | BASIC-PLUS.) Expression syntax corresponds closely to C |
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143 | expression syntax. Unlike most Unix utilities, Perl does not |
144 | arbitrarily limit the size of your data--if you've got the memory, | |
aa689395 | 145 | Perl can slurp in your whole file as a single string. Recursion is of |
0f31cffe | 146 | unlimited depth. And the tables used by hashes (sometimes called |
aa689395 | 147 | "associative arrays") grow as necessary to prevent degraded |
0f31cffe | 148 | performance. Perl can use sophisticated pattern matching techniques to |
14218588 | 149 | scan large amounts of data quickly. Although optimized for |
aa689395 | 150 | scanning text, Perl can also deal with binary data, and can make dbm |
151 | files look like hashes. Setuid Perl scripts are safer than C programs | |
14218588 | 152 | through a dataflow tracing mechanism that prevents many stupid |
aa689395 | 153 | security holes. |
154 | ||
155 | If you have a problem that would ordinarily use B<sed> or B<awk> or | |
156 | B<sh>, but it exceeds their capabilities or must run a little faster, | |
157 | and you don't want to write the silly thing in C, then Perl may be for | |
158 | you. There are also translators to turn your B<sed> and B<awk> | |
159 | scripts into Perl scripts. | |
a0d0e21e LW |
160 | |
161 | But wait, there's more... | |
162 | ||
19799a22 GS |
163 | Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete |
164 | rewrite that provides the following additional benefits: | |
a0d0e21e | 165 | |
19799a22 | 166 | =over |
a0d0e21e | 167 | |
19799a22 | 168 | =item * modularity and reusability using innumerable modules |
a0d0e21e | 169 | |
19799a22 | 170 | Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>. |
a0d0e21e | 171 | |
19799a22 | 172 | =item * embeddable and extensible |
a0d0e21e | 173 | |
19799a22 GS |
174 | Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>, |
175 | L<perlguts>, and L<xsubpp>. | |
a0d0e21e | 176 | |
19799a22 | 177 | =item * roll-your-own magic variables (including multiple simultaneous DBM implementations) |
a0d0e21e | 178 | |
19799a22 | 179 | Described in L<perltie> and L<AnyDBM_File>. |
a0d0e21e | 180 | |
19799a22 | 181 | =item * subroutines can now be overridden, autoloaded, and prototyped |
a0d0e21e | 182 | |
19799a22 | 183 | Described in L<perlsub>. |
a0d0e21e | 184 | |
19799a22 | 185 | =item * arbitrarily nested data structures and anonymous functions |
a0d0e21e | 186 | |
19799a22 | 187 | Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>. |
a0d0e21e | 188 | |
19799a22 | 189 | =item * object-oriented programming |
a0d0e21e | 190 | |
19799a22 | 191 | Described in L<perlobj>, L<perltoot>, and L<perlbot>. |
a0d0e21e | 192 | |
19799a22 | 193 | =item * compilability into C code or Perl bytecode |
a0d0e21e | 194 | |
19799a22 | 195 | Described in L<B> and L<B::Bytecode>. |
a0d0e21e | 196 | |
19799a22 | 197 | =item * support for light-weight processes (threads) |
a0d0e21e | 198 | |
19799a22 | 199 | Described in L<perlthrtut> and L<Thread>. |
a0d0e21e | 200 | |
19799a22 | 201 | =item * support for internationalization, localization, and Unicode |
a0d0e21e | 202 | |
19799a22 | 203 | Described in L<perllocale> and L<utf8>. |
a0d0e21e | 204 | |
19799a22 | 205 | =item * lexical scoping |
a0d0e21e | 206 | |
19799a22 | 207 | Described in L<perlsub>. |
a0d0e21e | 208 | |
19799a22 | 209 | =item * regular expression enhancements |
a0d0e21e | 210 | |
19799a22 | 211 | Described in L<perlre>, with additional examples in L<perlop>. |
a0d0e21e | 212 | |
14218588 | 213 | =item * enhanced debugger and interactive Perl environment, with integrated editor support |
a0d0e21e | 214 | |
19799a22 | 215 | Described in L<perldebug>. |
a0d0e21e | 216 | |
19799a22 | 217 | =item * POSIX 1003.1 compliant library |
5f05dabc | 218 | |
19799a22 | 219 | Described in L<POSIX>. |
5f05dabc | 220 | |
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221 | =back |
222 | ||
68dc0745 | 223 | Okay, that's I<definitely> enough hype. |
a0d0e21e | 224 | |
8e465e4e JH |
225 | =head1 AVAILABILITY |
226 | ||
14218588 | 227 | Perl is available for most operating systems, including virtually |
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228 | all Unix-like platforms. See L<perlport/"Supported Platforms"> |
229 | for a listing. | |
8bc4a6bb | 230 | |
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231 | =head1 ENVIRONMENT |
232 | ||
1e422769 | 233 | See L<perlrun>. |
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234 | |
235 | =head1 AUTHOR | |
236 | ||
19799a22 | 237 | Larry Wall <larry@wall.org>, with the help of oodles of other folks. |
a0d0e21e | 238 | |
a99b1639 TP |
239 | If your Perl success stories and testimonials may be of help to others |
240 | who wish to advocate the use of Perl in their applications, | |
241 | or if you wish to simply express your gratitude to Larry and the | |
19799a22 | 242 | Perl developers, please write to perl-thanks@perl.org . |
a99b1639 | 243 | |
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244 | =head1 FILES |
245 | ||
5f05dabc | 246 | "@INC" locations of perl libraries |
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247 | |
248 | =head1 SEE ALSO | |
249 | ||
250 | a2p awk to perl translator | |
251 | s2p sed to perl translator | |
252 | ||
19799a22 | 253 | http://www.perl.com/ the Perl Home Page |
5a3e7812 | 254 | http://www.perl.com/CPAN the Comprehensive Perl Archive |
19799a22 | 255 | |
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256 | =head1 DIAGNOSTICS |
257 | ||
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258 | The C<use warnings> pragma (and the B<-w> switch) produces some |
259 | lovely diagnostics. | |
a0d0e21e | 260 | |
5a964f20 TC |
261 | See L<perldiag> for explanations of all Perl's diagnostics. The C<use |
262 | diagnostics> pragma automatically turns Perl's normally terse warnings | |
263 | and errors into these longer forms. | |
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264 | |
265 | Compilation errors will tell you the line number of the error, with an | |
266 | indication of the next token or token type that was to be examined. | |
14218588 | 267 | (In a script passed to Perl via B<-e> switches, each |
a0d0e21e LW |
268 | B<-e> is counted as one line.) |
269 | ||
270 | Setuid scripts have additional constraints that can produce error | |
271 | messages such as "Insecure dependency". See L<perlsec>. | |
272 | ||
273 | Did we mention that you should definitely consider using the B<-w> | |
274 | switch? | |
275 | ||
276 | =head1 BUGS | |
277 | ||
278 | The B<-w> switch is not mandatory. | |
279 | ||
280 | Perl is at the mercy of your machine's definitions of various | |
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281 | operations such as type casting, atof(), and floating-point |
282 | output with sprintf(). | |
a0d0e21e | 283 | |
748a9306 | 284 | If your stdio requires a seek or eof between reads and writes on a |
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285 | particular stream, so does Perl. (This doesn't apply to sysread() |
286 | and syswrite().) | |
287 | ||
288 | While none of the built-in data types have any arbitrary size limits | |
289 | (apart from memory size), there are still a few arbitrary limits: a | |
a30ac152 GS |
290 | given variable name may not be longer than 251 characters. Line numbers |
291 | displayed by diagnostics are internally stored as short integers, | |
292 | so they are limited to a maximum of 65535 (higher numbers usually being | |
293 | affected by wraparound). | |
a0d0e21e | 294 | |
b0607b7a | 295 | You may mail your bug reports (be sure to include full configuration |
19799a22 GS |
296 | information as output by the myconfig program in the perl source |
297 | tree, or by C<perl -V>) to perlbug@perl.com . If you've succeeded | |
055fd3a9 | 298 | in compiling perl, the B<perlbug> script in the F<utils/> subdirectory |
19799a22 | 299 | can be used to help mail in a bug report. |
4633a7c4 | 300 | |
a0d0e21e LW |
301 | Perl actually stands for Pathologically Eclectic Rubbish Lister, but |
302 | don't tell anyone I said that. | |
303 | ||
304 | =head1 NOTES | |
305 | ||
306 | The Perl motto is "There's more than one way to do it." Divining | |
307 | how many more is left as an exercise to the reader. | |
308 | ||
4633a7c4 | 309 | The three principal virtues of a programmer are Laziness, |
a0d0e21e | 310 | Impatience, and Hubris. See the Camel Book for why. |
16d20bd9 | 311 |