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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
4755096e 15For ease of access, the Perl manual has been split up into several sections:
a0d0e21e 16
fb9cefb4 17 perl Perl overview (this section)
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18 perlfaq Perl frequently asked questions
19 perltoc Perl documentation table of contents
4755096e 20 perlbook Perl book information
760ac839 21
fb9cefb4 22 perlsyn Perl syntax
4755096e 23 perldata Perl data structures
fb9cefb4 24 perlop Perl operators and precedence
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25 perlsub Perl subroutines
26 perlfunc Perl builtin functions
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27 perlreftut Perl references short introduction
28 perldsc Perl data structures intro
4755096e 29 perlrequick Perl regular expressions quick start
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30 perlpod Perl plain old documentation
31 perlstyle Perl style guide
32 perltrap Perl traps for the unwary
4755096e 33
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34 perlrun Perl execution and options
35 perldiag Perl diagnostic messages
4755096e 36 perllexwarn Perl warnings and their control
10862624 37 perldebtut Perl debugging tutorial
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38 perldebug Perl debugging
39
fb9cefb4 40 perlvar Perl predefined variables
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41 perllol Perl data structures: arrays of arrays
42 perlopentut Perl open() tutorial
43 perlretut Perl regular expressions tutorial
2e1d04bc 44
4755096e 45 perlre Perl regular expressions, the rest of the story
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46 perlref Perl references, the rest of the story
47
fb9cefb4 48 perlform Perl formats
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49
50 perlboot Perl OO tutorial for beginners
51 perltoot Perl OO tutorial, part 1
52 perltootc Perl OO tutorial, part 2
53 perlobj Perl objects
54 perlbot Perl OO tricks and examples
55 perltie Perl objects hidden behind simple variables
760ac839 56
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57 perlipc Perl interprocess communication
58 perlfork Perl fork() information
59 perlnumber Perl number semantics
60 perlthrtut Perl threads tutorial
61
62 perlport Perl portability guide
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63 perllocale Perl locale support
64 perlunicode Perl unicode support
65 perlebcdic Considerations for running Perl on EBCDIC platforms
c2e66d9e 66
d396a558 67 perlsec Perl security
4755096e 68
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69 perlmod Perl modules: how they work
70 perlmodlib Perl modules: how to write and use
71 perlmodinstall Perl modules: how to install from CPAN
72 perlnewmod Perl modules: preparing a new module for distribution
760ac839 73
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74 perlfaq1 General Questions About Perl
75 perlfaq2 Obtaining and Learning about Perl
76 perlfaq3 Programming Tools
77 perlfaq4 Data Manipulation
78 perlfaq5 Files and Formats
79 perlfaq6 Regexes
80 perlfaq7 Perl Language Issues
81 perlfaq8 System Interaction
82 perlfaq9 Networking
760ac839 83
4755096e 84 perlcompile Perl compiler suite intro
760ac839 85
fb9cefb4 86 perlembed Perl ways to embed perl in your C or C++ application
055fd3a9 87 perldebguts Perl debugging guts and tips
fb9cefb4 88 perlxstut Perl XS tutorial
4755096e 89 perlxs Perl XS application programming interface
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90 perlguts Perl internal functions for those doing extensions
91 perlcall Perl calling conventions from C
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92 perlutil utilities packaged with the Perl distribution
93 perlfilter Perl source filters
94 perldbmfilter Perl DBM filters
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95 perlapi Perl API listing (autogenerated)
96 perlintern Perl internal functions (autogenerated)
4755096e 97 perlapio Perl internal IO abstraction interface
e50bb9a1 98 perltodo Perl things to do
e8cd7eae 99 perlhack Perl hackers guide
4755096e 100
fb9cefb4 101 perlhist Perl history records
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102 perldelta Perl changes since previous version
103 perl56delta Perl changes in version 5.6
104 perl5005delta Perl changes in version 5.005
105 perl5004delta Perl changes in version 5.004
d516a115 106
37d4d706 107 perlaix Perl notes for AIX
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108 perlamiga Perl notes for Amiga
109 perlcygwin Perl notes for Cygwin
110 perldos Perl notes for DOS
111 perlhpux Perl notes for HP-UX
da369004 112 perlmachten Perl notes for Power MachTen
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113 perlos2 Perl notes for OS/2
114 perlos390 Perl notes for OS/390
c2e66d9e 115 perlposix-bc Perl notes for POSIX-BC
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116 perlvms Perl notes for VMS
117 perlwin32 Perl notes for Windows
118
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119(If you're intending to read these straight through for the first time,
120the suggested order will tend to reduce the number of forward references.)
121
19799a22 122By default, the manpages listed above are installed in the
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123F</usr/local/man/> directory.
124
125Extensive additional documentation for Perl modules is available. The
126default configuration for perl will place this additional documentation
127in the F</usr/local/lib/perl5/man> directory (or else in the F<man>
128subdirectory of the Perl library directory). Some of this additional
129documentation is distributed standard with Perl, but you'll also find
130documentation for third-party modules there.
131
132You should be able to view Perl's documentation with your man(1)
133program by including the proper directories in the appropriate start-up
134files, or in the MANPATH environment variable. To find out where the
135configuration has installed the manpages, type:
16d20bd9 136
760ac839 137 perl -V:man.dir
16d20bd9 138
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139If the directories have a common stem, such as F</usr/local/man/man1>
140and F</usr/local/man/man3>, you need only to add that stem
141(F</usr/local/man>) to your man(1) configuration files or your MANPATH
142environment variable. If they do not share a stem, you'll have to add
143both stems.
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144
145If that doesn't work for some reason, you can still use the
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146supplied F<perldoc> script to view module information. You might
147also look into getting a replacement man program.
16d20bd9 148
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149If something strange has gone wrong with your program and you're not
150sure where you should look for help, try the B<-w> switch first. It
151will often point out exactly where the trouble is.
152
153=head1 DESCRIPTION
154
5f05dabc 155Perl is a language optimized for scanning arbitrary
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156text files, extracting information from those text files, and printing
157reports based on that information. It's also a good language for many
158system management tasks. The language is intended to be practical
159(easy to use, efficient, complete) rather than beautiful (tiny,
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160elegant, minimal).
161
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162Perl combines (in the author's opinion, anyway) some of the best
163features of C, B<sed>, B<awk>, and B<sh>, so people familiar with
164those languages should have little difficulty with it. (Language
165historians will also note some vestiges of B<csh>, Pascal, and even
14218588 166BASIC-PLUS.) Expression syntax corresponds closely to C
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167expression syntax. Unlike most Unix utilities, Perl does not
168arbitrarily limit the size of your data--if you've got the memory,
aa689395 169Perl can slurp in your whole file as a single string. Recursion is of
0f31cffe 170unlimited depth. And the tables used by hashes (sometimes called
aa689395 171"associative arrays") grow as necessary to prevent degraded
0f31cffe 172performance. Perl can use sophisticated pattern matching techniques to
14218588 173scan large amounts of data quickly. Although optimized for
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174scanning text, Perl can also deal with binary data, and can make dbm
175files look like hashes. Setuid Perl scripts are safer than C programs
14218588 176through a dataflow tracing mechanism that prevents many stupid
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177security holes.
178
179If you have a problem that would ordinarily use B<sed> or B<awk> or
180B<sh>, but it exceeds their capabilities or must run a little faster,
181and you don't want to write the silly thing in C, then Perl may be for
182you. There are also translators to turn your B<sed> and B<awk>
183scripts into Perl scripts.
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184
185But wait, there's more...
186
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187Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete
188rewrite that provides the following additional benefits:
a0d0e21e 189
19799a22 190=over
a0d0e21e 191
19799a22 192=item * modularity and reusability using innumerable modules
a0d0e21e 193
19799a22 194Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>.
a0d0e21e 195
19799a22 196=item * embeddable and extensible
a0d0e21e 197
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198Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>,
199L<perlguts>, and L<xsubpp>.
a0d0e21e 200
19799a22 201=item * roll-your-own magic variables (including multiple simultaneous DBM implementations)
a0d0e21e 202
19799a22 203Described in L<perltie> and L<AnyDBM_File>.
a0d0e21e 204
19799a22 205=item * subroutines can now be overridden, autoloaded, and prototyped
a0d0e21e 206
19799a22 207Described in L<perlsub>.
a0d0e21e 208
19799a22 209=item * arbitrarily nested data structures and anonymous functions
a0d0e21e 210
19799a22 211Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>.
a0d0e21e 212
19799a22 213=item * object-oriented programming
a0d0e21e 214
19799a22 215Described in L<perlobj>, L<perltoot>, and L<perlbot>.
a0d0e21e 216
19799a22 217=item * compilability into C code or Perl bytecode
a0d0e21e 218
19799a22 219Described in L<B> and L<B::Bytecode>.
a0d0e21e 220
19799a22 221=item * support for light-weight processes (threads)
a0d0e21e 222
19799a22 223Described in L<perlthrtut> and L<Thread>.
a0d0e21e 224
19799a22 225=item * support for internationalization, localization, and Unicode
a0d0e21e 226
19799a22 227Described in L<perllocale> and L<utf8>.
a0d0e21e 228
19799a22 229=item * lexical scoping
a0d0e21e 230
19799a22 231Described in L<perlsub>.
a0d0e21e 232
19799a22 233=item * regular expression enhancements
a0d0e21e 234
19799a22 235Described in L<perlre>, with additional examples in L<perlop>.
a0d0e21e 236
14218588 237=item * enhanced debugger and interactive Perl environment, with integrated editor support
a0d0e21e 238
19799a22 239Described in L<perldebug>.
a0d0e21e 240
19799a22 241=item * POSIX 1003.1 compliant library
5f05dabc 242
19799a22 243Described in L<POSIX>.
5f05dabc 244
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245=back
246
68dc0745 247Okay, that's I<definitely> enough hype.
a0d0e21e 248
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249=head1 AVAILABILITY
250
14218588 251Perl is available for most operating systems, including virtually
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252all Unix-like platforms. See L<perlport/"Supported Platforms">
253for a listing.
8bc4a6bb 254
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255=head1 ENVIRONMENT
256
1e422769 257See L<perlrun>.
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258
259=head1 AUTHOR
260
19799a22 261Larry Wall <larry@wall.org>, with the help of oodles of other folks.
a0d0e21e 262
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263If your Perl success stories and testimonials may be of help to others
264who wish to advocate the use of Perl in their applications,
265or if you wish to simply express your gratitude to Larry and the
19799a22 266Perl developers, please write to perl-thanks@perl.org .
a99b1639 267
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268=head1 FILES
269
5f05dabc 270 "@INC" locations of perl libraries
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271
272=head1 SEE ALSO
273
274 a2p awk to perl translator
275 s2p sed to perl translator
276
19799a22 277 http://www.perl.com/ the Perl Home Page
5a3e7812 278 http://www.perl.com/CPAN the Comprehensive Perl Archive
19799a22 279
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280=head1 DIAGNOSTICS
281
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282The C<use warnings> pragma (and the B<-w> switch) produces some
283lovely diagnostics.
a0d0e21e 284
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285See L<perldiag> for explanations of all Perl's diagnostics. The C<use
286diagnostics> pragma automatically turns Perl's normally terse warnings
287and errors into these longer forms.
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288
289Compilation errors will tell you the line number of the error, with an
290indication of the next token or token type that was to be examined.
14218588 291(In a script passed to Perl via B<-e> switches, each
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292B<-e> is counted as one line.)
293
294Setuid scripts have additional constraints that can produce error
295messages such as "Insecure dependency". See L<perlsec>.
296
297Did we mention that you should definitely consider using the B<-w>
298switch?
299
300=head1 BUGS
301
302The B<-w> switch is not mandatory.
303
304Perl is at the mercy of your machine's definitions of various
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305operations such as type casting, atof(), and floating-point
306output with sprintf().
a0d0e21e 307
748a9306 308If your stdio requires a seek or eof between reads and writes on a
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309particular stream, so does Perl. (This doesn't apply to sysread()
310and syswrite().)
311
312While none of the built-in data types have any arbitrary size limits
313(apart from memory size), there are still a few arbitrary limits: a
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314given variable name may not be longer than 251 characters. Line numbers
315displayed by diagnostics are internally stored as short integers,
316so they are limited to a maximum of 65535 (higher numbers usually being
317affected by wraparound).
a0d0e21e 318
b0607b7a 319You may mail your bug reports (be sure to include full configuration
19799a22 320information as output by the myconfig program in the perl source
7f2de2d2 321tree, or by C<perl -V>) to perlbug@perl.org . If you've succeeded
055fd3a9 322in compiling perl, the B<perlbug> script in the F<utils/> subdirectory
19799a22 323can be used to help mail in a bug report.
4633a7c4 324
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325Perl actually stands for Pathologically Eclectic Rubbish Lister, but
326don't tell anyone I said that.
327
328=head1 NOTES
329
330The Perl motto is "There's more than one way to do it." Divining
331how many more is left as an exercise to the reader.
332
4633a7c4 333The three principal virtues of a programmer are Laziness,
a0d0e21e 334Impatience, and Hubris. See the Camel Book for why.
16d20bd9 335