3 perl - Practical Extraction and Report Language
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> ]...>
15 For ease of access, the Perl manual has been split up into several sections:
17 perl Perl overview (this section)
18 perlfaq Perl frequently asked questions
19 perltoc Perl documentation table of contents
20 perlbook Perl book information
23 perldata Perl data structures
24 perlop Perl operators and precedence
25 perlsub Perl subroutines
26 perlfunc Perl builtin functions
27 perlreftut Perl references short introduction
28 perldsc Perl data structures intro
29 perlrequick Perl regular expressions quick start
30 perlpod Perl plain old documentation
31 perlstyle Perl style guide
32 perltrap Perl traps for the unwary
34 perlrun Perl execution and options
35 perldiag Perl diagnostic messages
36 perllexwarn Perl warnings and their control
37 perldebtut Perl debugging tutorial
38 perldebug Perl debugging
40 perlvar Perl predefined variables
41 perllol Perl data structures: arrays of arrays
42 perlopentut Perl open() tutorial
43 perlretut Perl regular expressions tutorial
45 perlre Perl regular expressions, the rest of the story
46 perlref Perl references, the rest of the story
50 perlboot Perl OO tutorial for beginners
51 perltoot Perl OO tutorial, part 1
52 perltootc Perl OO tutorial, part 2
54 perlbot Perl OO tricks and examples
55 perltie Perl objects hidden behind simple variables
57 perlipc Perl interprocess communication
58 perlfork Perl fork() information
59 perlnumber Perl number semantics
60 perlthrtut Perl threads tutorial
62 perlport Perl portability guide
63 perllocale Perl locale support
64 perlunicode Perl unicode support
65 perlebcdic Considerations for running Perl on EBCDIC platforms
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
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
80 perlfaq7 Perl Language Issues
81 perlfaq8 System Interaction
84 perlcompile Perl compiler suite intro
86 perlembed Perl ways to embed perl in your C or C++ application
87 perldebguts Perl debugging guts and tips
88 perlxstut Perl XS tutorial
89 perlxs Perl XS application programming interface
90 perlclib Internal replacements for standard C library functions
91 perlguts Perl internal functions for those doing extensions
92 perlcall Perl calling conventions from C
93 perlutil utilities packaged with the Perl distribution
94 perlfilter Perl source filters
95 perldbmfilter Perl DBM filters
96 perlapi Perl API listing (autogenerated)
97 perlintern Perl internal functions (autogenerated)
98 perliol C API for Perl's implementation of IO in Layers
99 perlapio Perl internal IO abstraction interface
100 perltodo Perl things to do
101 perlhack Perl hackers guide
103 perlhist Perl history records
104 perldelta Perl changes since previous version
105 perl572delta Perl changes in version 5.7.2
106 perl571delta Perl changes in version 5.7.1
107 perl570delta Perl changes in version 5.7.0
108 perl56delta Perl changes in version 5.6
109 perl5005delta Perl changes in version 5.005
110 perl5004delta Perl changes in version 5.004
112 perlaix Perl notes for AIX
113 perlamiga Perl notes for AmigaOS
114 perlapollo Perl notes for Apollo DomainOS
115 perlbeos Perl notes for BeOS
116 perlbs2000 Perl notes for POSIX-BC BS2000
117 perlcygwin Perl notes for Cygwin
118 perldgux Perl notes for DG/UX
119 perldos Perl notes for DOS
120 perlepoc Perl notes for EPOC
121 perlhpux Perl notes for HP-UX
122 perlhurd Perl notes for Hurd
123 perlmachten Perl notes for Power MachTen
124 perlmacos Perl notes for Mac OS (Classic)
125 perlmint Perl notes for MiNT
126 perlmpeix Perl notes for MPE/iX
127 perlnetware Perl notes for NetWare
128 perlos2 Perl notes for OS/2
129 perlos390 Perl notes for OS/390
130 perlplan9 Perl notes for Plan 9
131 perlqnx Perl notes for QNX
132 perlsolaris Perl notes for Solaris
133 perltru64 Perl notes for Tru64
134 perlvmesa Perl notes for VM/ESA
135 perlvms Perl notes for VMS
136 perlvos Perl notes for Stratus VOS
137 perlwin32 Perl notes for Windows
139 (If you're intending to read these straight through for the first time,
140 the suggested order will tend to reduce the number of forward references.)
142 By default, the manpages listed above are installed in the
143 F</usr/local/man/> directory.
145 Extensive additional documentation for Perl modules is available. The
146 default configuration for perl will place this additional documentation
147 in the F</usr/local/lib/perl5/man> directory (or else in the F<man>
148 subdirectory of the Perl library directory). Some of this additional
149 documentation is distributed standard with Perl, but you'll also find
150 documentation for third-party modules there.
152 You should be able to view Perl's documentation with your man(1)
153 program by including the proper directories in the appropriate start-up
154 files, or in the MANPATH environment variable. To find out where the
155 configuration has installed the manpages, type:
159 If the directories have a common stem, such as F</usr/local/man/man1>
160 and F</usr/local/man/man3>, you need only to add that stem
161 (F</usr/local/man>) to your man(1) configuration files or your MANPATH
162 environment variable. If they do not share a stem, you'll have to add
165 If that doesn't work for some reason, you can still use the
166 supplied F<perldoc> script to view module information. You might
167 also look into getting a replacement man program.
169 If something strange has gone wrong with your program and you're not
170 sure where you should look for help, try the B<-w> switch first. It
171 will often point out exactly where the trouble is.
175 Perl is a language optimized for scanning arbitrary
176 text files, extracting information from those text files, and printing
177 reports based on that information. It's also a good language for many
178 system management tasks. The language is intended to be practical
179 (easy to use, efficient, complete) rather than beautiful (tiny,
182 Perl combines (in the author's opinion, anyway) some of the best
183 features of C, B<sed>, B<awk>, and B<sh>, so people familiar with
184 those languages should have little difficulty with it. (Language
185 historians will also note some vestiges of B<csh>, Pascal, and even
186 BASIC-PLUS.) Expression syntax corresponds closely to C
187 expression syntax. Unlike most Unix utilities, Perl does not
188 arbitrarily limit the size of your data--if you've got the memory,
189 Perl can slurp in your whole file as a single string. Recursion is of
190 unlimited depth. And the tables used by hashes (sometimes called
191 "associative arrays") grow as necessary to prevent degraded
192 performance. Perl can use sophisticated pattern matching techniques to
193 scan large amounts of data quickly. Although optimized for
194 scanning text, Perl can also deal with binary data, and can make dbm
195 files look like hashes. Setuid Perl scripts are safer than C programs
196 through a dataflow tracing mechanism that prevents many stupid
199 If you have a problem that would ordinarily use B<sed> or B<awk> or
200 B<sh>, but it exceeds their capabilities or must run a little faster,
201 and you don't want to write the silly thing in C, then Perl may be for
202 you. There are also translators to turn your B<sed> and B<awk>
203 scripts into Perl scripts.
205 But wait, there's more...
207 Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete
208 rewrite that provides the following additional benefits:
214 modularity and reusability using innumerable modules
216 Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>.
220 embeddable and extensible
222 Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>,
223 L<perlguts>, and L<xsubpp>.
227 roll-your-own magic variables (including multiple simultaneous DBM implementations)
229 Described in L<perltie> and L<AnyDBM_File>.
233 subroutines can now be overridden, autoloaded, and prototyped
235 Described in L<perlsub>.
239 arbitrarily nested data structures and anonymous functions
241 Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>.
245 object-oriented programming
247 Described in L<perlobj>, L<perltoot>, and L<perlbot>.
251 compilability into C code or Perl bytecode
253 Described in L<B> and L<B::Bytecode>.
257 support for light-weight processes (threads)
259 Described in L<perlthrtut> and L<Thread>.
263 support for internationalization, localization, and Unicode
265 Described in L<perllocale> and L<utf8>.
271 Described in L<perlsub>.
275 regular expression enhancements
277 Described in L<perlre>, with additional examples in L<perlop>.
281 enhanced debugger and interactive Perl environment,
282 with integrated editor support
284 Described in L<perldebug>.
288 POSIX 1003.1 compliant library
290 Described in L<POSIX>.
294 Okay, that's I<definitely> enough hype.
298 Perl is available for most operating systems, including virtually
299 all Unix-like platforms. See L<perlport/"Supported Platforms">
308 Larry Wall <larry@wall.org>, with the help of oodles of other folks.
310 If your Perl success stories and testimonials may be of help to others
311 who wish to advocate the use of Perl in their applications,
312 or if you wish to simply express your gratitude to Larry and the
313 Perl developers, please write to perl-thanks@perl.org .
317 "@INC" locations of perl libraries
321 a2p awk to perl translator
322 s2p sed to perl translator
324 http://www.perl.com/ the Perl Home Page
325 http://www.perl.com/CPAN the Comprehensive Perl Archive
329 The C<use warnings> pragma (and the B<-w> switch) produces some
332 See L<perldiag> for explanations of all Perl's diagnostics. The C<use
333 diagnostics> pragma automatically turns Perl's normally terse warnings
334 and errors into these longer forms.
336 Compilation errors will tell you the line number of the error, with an
337 indication of the next token or token type that was to be examined.
338 (In a script passed to Perl via B<-e> switches, each
339 B<-e> is counted as one line.)
341 Setuid scripts have additional constraints that can produce error
342 messages such as "Insecure dependency". See L<perlsec>.
344 Did we mention that you should definitely consider using the B<-w>
349 The B<-w> switch is not mandatory.
351 Perl is at the mercy of your machine's definitions of various
352 operations such as type casting, atof(), and floating-point
353 output with sprintf().
355 If your stdio requires a seek or eof between reads and writes on a
356 particular stream, so does Perl. (This doesn't apply to sysread()
359 While none of the built-in data types have any arbitrary size limits
360 (apart from memory size), there are still a few arbitrary limits: a
361 given variable name may not be longer than 251 characters. Line numbers
362 displayed by diagnostics are internally stored as short integers,
363 so they are limited to a maximum of 65535 (higher numbers usually being
364 affected by wraparound).
366 You may mail your bug reports (be sure to include full configuration
367 information as output by the myconfig program in the perl source
368 tree, or by C<perl -V>) to perlbug@perl.org . If you've succeeded
369 in compiling perl, the B<perlbug> script in the F<utils/> subdirectory
370 can be used to help mail in a bug report.
372 Perl actually stands for Pathologically Eclectic Rubbish Lister, but
373 don't tell anyone I said that.
377 The Perl motto is "There's more than one way to do it." Divining
378 how many more is left as an exercise to the reader.
380 The three principal virtues of a programmer are Laziness,
381 Impatience, and Hubris. See the Camel Book for why.