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1=head1 NAME
2
3perl - Practical Extraction and Report Language
4
5=head1 SYNOPSIS
6
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7B<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
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15For ease of access, the Perl manual has been split up into several
16sections:
a0d0e21e 17
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18 perl Perl overview (this section)
19 perldelta Perl changes since previous version
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20 perl5005delta Perl changes in version 5.005
21 perl5004delta Perl changes in version 5.004
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22 perlfaq Perl frequently asked questions
23 perltoc Perl documentation table of contents
760ac839 24
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25 perldata Perl data structures
26 perlsyn Perl syntax
27 perlop Perl operators and precedence
28 perlre Perl regular expressions
29 perlrun Perl execution and options
30 perlfunc Perl builtin functions
2605996a 31 perlopentut Perl open() tutorial
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32 perlvar Perl predefined variables
33 perlsub Perl subroutines
34 perlmod Perl modules: how they work
35 perlmodlib Perl modules: how to write and use
36 perlmodinstall Perl modules: how to install from CPAN
37 perlform Perl formats
38 perllocale Perl locale support
760ac839 39
a1e2a320 40 perlreftut Perl references short introduction
19799a22 41 perlref Perl references, the rest of the story
fb9cefb4 42 perldsc Perl data structures intro
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43 perllol Perl data structures: arrays of arrays
44 perltoot Perl OO tutorial, part 1
45 perltootc Perl OO tutorial, part 2
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46 perlobj Perl objects
47 perltie Perl objects hidden behind simple variables
48 perlbot Perl OO tricks and examples
49 perlipc Perl interprocess communication
2605996a 50 perlthrtut Perl threads tutorial
9fe6733a 51 perldbmfilter Perl DBM Filters
760ac839 52
54a137f5 53 perlcompile Perl compiler suite intro
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54 perldebug Perl debugging
55 perldiag Perl diagnostic messages
56 perlsec Perl security
57 perltrap Perl traps for the unwary
58 perlport Perl portability guide
59 perlstyle Perl style guide
760ac839 60
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61 perlpod Perl plain old documentation
62 perlbook Perl book information
760ac839 63
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64 perlembed Perl ways to embed perl in your C or C++ application
65 perlapio Perl internal IO abstraction interface
66 perlxs Perl XS application programming interface
67 perlxstut Perl XS tutorial
68 perlguts Perl internal functions for those doing extensions
69 perlcall Perl calling conventions from C
a0d0e21e 70
e50bb9a1 71 perltodo Perl things to do
fb9cefb4 72 perlhist Perl history records
d516a115 73
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74(If you're intending to read these straight through for the first time,
75the suggested order will tend to reduce the number of forward references.)
76
19799a22 77By default, the manpages listed above are installed in the
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78F</usr/local/man/> directory.
79
80Extensive additional documentation for Perl modules is available. The
81default configuration for perl will place this additional documentation
82in the F</usr/local/lib/perl5/man> directory (or else in the F<man>
83subdirectory of the Perl library directory). Some of this additional
84documentation is distributed standard with Perl, but you'll also find
85documentation for third-party modules there.
86
87You should be able to view Perl's documentation with your man(1)
88program by including the proper directories in the appropriate start-up
89files, or in the MANPATH environment variable. To find out where the
90configuration has installed the manpages, type:
16d20bd9 91
760ac839 92 perl -V:man.dir
16d20bd9 93
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94If the directories have a common stem, such as F</usr/local/man/man1>
95and F</usr/local/man/man3>, you need only to add that stem
96(F</usr/local/man>) to your man(1) configuration files or your MANPATH
97environment variable. If they do not share a stem, you'll have to add
98both stems.
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99
100If that doesn't work for some reason, you can still use the
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101supplied F<perldoc> script to view module information. You might
102also look into getting a replacement man program.
16d20bd9 103
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104If something strange has gone wrong with your program and you're not
105sure where you should look for help, try the B<-w> switch first. It
106will often point out exactly where the trouble is.
107
108=head1 DESCRIPTION
109
5f05dabc 110Perl is a language optimized for scanning arbitrary
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111text files, extracting information from those text files, and printing
112reports based on that information. It's also a good language for many
113system management tasks. The language is intended to be practical
114(easy to use, efficient, complete) rather than beautiful (tiny,
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115elegant, minimal).
116
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117Perl combines (in the author's opinion, anyway) some of the best
118features of C, B<sed>, B<awk>, and B<sh>, so people familiar with
119those languages should have little difficulty with it. (Language
120historians will also note some vestiges of B<csh>, Pascal, and even
14218588 121BASIC-PLUS.) Expression syntax corresponds closely to C
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122expression syntax. Unlike most Unix utilities, Perl does not
123arbitrarily limit the size of your data--if you've got the memory,
aa689395 124Perl can slurp in your whole file as a single string. Recursion is of
0f31cffe 125unlimited depth. And the tables used by hashes (sometimes called
aa689395 126"associative arrays") grow as necessary to prevent degraded
0f31cffe 127performance. Perl can use sophisticated pattern matching techniques to
14218588 128scan large amounts of data quickly. Although optimized for
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129scanning text, Perl can also deal with binary data, and can make dbm
130files look like hashes. Setuid Perl scripts are safer than C programs
14218588 131through a dataflow tracing mechanism that prevents many stupid
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132security holes.
133
134If you have a problem that would ordinarily use B<sed> or B<awk> or
135B<sh>, but it exceeds their capabilities or must run a little faster,
136and you don't want to write the silly thing in C, then Perl may be for
137you. There are also translators to turn your B<sed> and B<awk>
138scripts into Perl scripts.
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139
140But wait, there's more...
141
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142Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete
143rewrite that provides the following additional benefits:
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19799a22 145=over
a0d0e21e 146
19799a22 147=item * modularity and reusability using innumerable modules
a0d0e21e 148
19799a22 149Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>.
a0d0e21e 150
19799a22 151=item * embeddable and extensible
a0d0e21e 152
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153Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>,
154L<perlguts>, and L<xsubpp>.
a0d0e21e 155
19799a22 156=item * roll-your-own magic variables (including multiple simultaneous DBM implementations)
a0d0e21e 157
19799a22 158Described in L<perltie> and L<AnyDBM_File>.
a0d0e21e 159
19799a22 160=item * subroutines can now be overridden, autoloaded, and prototyped
a0d0e21e 161
19799a22 162Described in L<perlsub>.
a0d0e21e 163
19799a22 164=item * arbitrarily nested data structures and anonymous functions
a0d0e21e 165
19799a22 166Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>.
a0d0e21e 167
19799a22 168=item * object-oriented programming
a0d0e21e 169
19799a22 170Described in L<perlobj>, L<perltoot>, and L<perlbot>.
a0d0e21e 171
19799a22 172=item * compilability into C code or Perl bytecode
a0d0e21e 173
19799a22 174Described in L<B> and L<B::Bytecode>.
a0d0e21e 175
19799a22 176=item * support for light-weight processes (threads)
a0d0e21e 177
19799a22 178Described in L<perlthrtut> and L<Thread>.
a0d0e21e 179
19799a22 180=item * support for internationalization, localization, and Unicode
a0d0e21e 181
19799a22 182Described in L<perllocale> and L<utf8>.
a0d0e21e 183
19799a22 184=item * lexical scoping
a0d0e21e 185
19799a22 186Described in L<perlsub>.
a0d0e21e 187
19799a22 188=item * regular expression enhancements
a0d0e21e 189
19799a22 190Described in L<perlre>, with additional examples in L<perlop>.
a0d0e21e 191
14218588 192=item * enhanced debugger and interactive Perl environment, with integrated editor support
a0d0e21e 193
19799a22 194Described in L<perldebug>.
a0d0e21e 195
19799a22 196=item * POSIX 1003.1 compliant library
5f05dabc 197
19799a22 198Described in L<POSIX>.
5f05dabc 199
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200=back
201
68dc0745 202Okay, that's I<definitely> enough hype.
a0d0e21e 203
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204=head1 AVAILABILITY
205
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206Perl is available for most operating systems, including virtually
207all Unix-like platforms.
8e465e4e 208
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209As of May 1999, the following platforms are able to build Perl
210from the standard source code distribution available at
19799a22 211http://www.perl.com/CPAN/src/index.html
8e465e4e 212
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213 AIX Linux SCO ODT/OSR
214 A/UX MachTen Solaris
215 BeOS MPE/iX SunOS
216 BSD/OS NetBSD SVR4
217 DG/UX NextSTEP Tru64 UNIX 3)
218 DomainOS OpenBSD Ultrix
219 DOS DJGPP 1) OpenSTEP UNICOS
220 DYNIX/ptx OS/2 VMS
221 FreeBSD OS390 2) VOS
222 HP-UX PowerMAX Windows 3.1 1)
223 Hurd QNX Windows 95 1) 4)
224 IRIX Windows 98 1) 4)
225 Windows NT 1) 4)
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226
227 1) in DOS mode either the DOS or OS/2 ports can be used
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228 2) formerly known as MVS
229 3) formerly known as Digital UNIX and before that DEC OSF/1
873b149f 230 4) compilers: Borland, Cygwin, Mingw32 EGCS/GCC, VC++
58493fc4 231
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232The following platforms have been known to build Perl from source,
233but we haven't been able to verify their status for the current release,
234either because the hardware/software platforms are rare or
19799a22 235because we don't have an active champion on these platforms--or both.
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236
237 3b1 FPS Plan 9
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238 AmigaOS GENIX PowerUX
239 ConvexOS Greenhills RISC/os
240 CX/UX ISC Stellar
241 DC/OSx MachTen 68k SVR2
242 DDE SMES MiNT TI1500
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243 DOS EMX MPC TitanOS
244 Dynix NEWS-OS UNICOS/mk
245 EP/IX Opus Unisys Dynix
246 ESIX Unixware
8e465e4e 247
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248Support for the following platforms is planned for the next major
249Perl release.
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250
251 BS2000
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252 Netware
253 Rhapsody
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254 VM/ESA
255
256The following platforms have their own source code distributions and
19799a22 257binaries available via http://www.perl.com/CPAN/ports/index.html.
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258
259 Perl release
260
261 AS/400 5.003
2e04d155 262 MacOS 5.004
04251ce8 263 Netware 5.003_07
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264 Tandem Guardian 5.004
265
266The following platforms have only binaries available via
19799a22 267http://www.perl.com/CPAN/ports/index.html.
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268
269 Perl release
270
d845c4a6 271 Acorn RISCOS 5.005_02
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272 AOS 5.002
273 LynxOS 5.004_02
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275=head1 ENVIRONMENT
276
1e422769 277See L<perlrun>.
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278
279=head1 AUTHOR
280
19799a22 281Larry Wall <larry@wall.org>, with the help of oodles of other folks.
a0d0e21e 282
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283If your Perl success stories and testimonials may be of help to others
284who wish to advocate the use of Perl in their applications,
285or if you wish to simply express your gratitude to Larry and the
19799a22 286Perl developers, please write to perl-thanks@perl.org .
a99b1639 287
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288=head1 FILES
289
5f05dabc 290 "@INC" locations of perl libraries
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291
292=head1 SEE ALSO
293
294 a2p awk to perl translator
295 s2p sed to perl translator
296
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297 http://www.perl.com/ the Perl Home Page
298 http://www.perl.com/CPAN the Comphrehensive Perl Archive
299
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300=head1 DIAGNOSTICS
301
302The B<-w> switch produces some lovely diagnostics.
303
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304See L<perldiag> for explanations of all Perl's diagnostics. The C<use
305diagnostics> pragma automatically turns Perl's normally terse warnings
306and errors into these longer forms.
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307
308Compilation errors will tell you the line number of the error, with an
309indication of the next token or token type that was to be examined.
14218588 310(In a script passed to Perl via B<-e> switches, each
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311B<-e> is counted as one line.)
312
313Setuid scripts have additional constraints that can produce error
314messages such as "Insecure dependency". See L<perlsec>.
315
316Did we mention that you should definitely consider using the B<-w>
317switch?
318
319=head1 BUGS
320
321The B<-w> switch is not mandatory.
322
323Perl is at the mercy of your machine's definitions of various
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324operations such as type casting, atof(), and floating-point
325output with sprintf().
a0d0e21e 326
748a9306 327If your stdio requires a seek or eof between reads and writes on a
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328particular stream, so does Perl. (This doesn't apply to sysread()
329and syswrite().)
330
331While none of the built-in data types have any arbitrary size limits
332(apart from memory size), there are still a few arbitrary limits: a
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333given variable name may not be longer than 251 characters. Line numbers
334displayed by diagnostics are internally stored as short integers,
335so they are limited to a maximum of 65535 (higher numbers usually being
336affected by wraparound).
a0d0e21e 337
b0607b7a 338You may mail your bug reports (be sure to include full configuration
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339information as output by the myconfig program in the perl source
340tree, or by C<perl -V>) to perlbug@perl.com . If you've succeeded
341in compiling perl, the perlbug script in the utils/ subdirectory
342can be used to help mail in a bug report.
4633a7c4 343
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344Perl actually stands for Pathologically Eclectic Rubbish Lister, but
345don't tell anyone I said that.
346
347=head1 NOTES
348
349The Perl motto is "There's more than one way to do it." Divining
350how many more is left as an exercise to the reader.
351
4633a7c4 352The three principal virtues of a programmer are Laziness,
a0d0e21e 353Impatience, and Hubris. See the Camel Book for why.
16d20bd9 354