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 perlguts Perl internal functions for those doing extensions
91 perlcall Perl calling conventions from C
92 perlutil utilities packaged with the Perl distribution
93 perlfilter Perl source filters
94 perldbmfilter Perl DBM filters
95 perlapi Perl API listing (autogenerated)
96 perlintern Perl internal functions (autogenerated)
97 perlapio Perl internal IO abstraction interface
98 perltodo Perl things to do
99 perlhack Perl hackers guide
101 perlhist Perl history records
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
107 perlaix Perl notes for AIX
108 perlamiga Perl notes for Amiga
109 perlcygwin Perl notes for Cygwin
110 perldos Perl notes for DOS
111 perlepoc Perl notes for EPOC
112 perlhpux Perl notes for HP-UX
113 perlmachten Perl notes for Power MachTen
114 perlmpeix Perl notes for MPE/iX
115 perlos2 Perl notes for OS/2
116 perlos390 Perl notes for OS/390
117 perlposix-bc Perl notes for POSIX-BC
118 perlsolaris Perl notes for Solaris
119 perlvms Perl notes for VMS
120 perlvos Perl notes for Stratus VOS
121 perlwin32 Perl notes for Windows
123 (If you're intending to read these straight through for the first time,
124 the suggested order will tend to reduce the number of forward references.)
126 By default, the manpages listed above are installed in the
127 F</usr/local/man/> directory.
129 Extensive additional documentation for Perl modules is available. The
130 default configuration for perl will place this additional documentation
131 in the F</usr/local/lib/perl5/man> directory (or else in the F<man>
132 subdirectory of the Perl library directory). Some of this additional
133 documentation is distributed standard with Perl, but you'll also find
134 documentation for third-party modules there.
136 You should be able to view Perl's documentation with your man(1)
137 program by including the proper directories in the appropriate start-up
138 files, or in the MANPATH environment variable. To find out where the
139 configuration has installed the manpages, type:
143 If the directories have a common stem, such as F</usr/local/man/man1>
144 and F</usr/local/man/man3>, you need only to add that stem
145 (F</usr/local/man>) to your man(1) configuration files or your MANPATH
146 environment variable. If they do not share a stem, you'll have to add
149 If that doesn't work for some reason, you can still use the
150 supplied F<perldoc> script to view module information. You might
151 also look into getting a replacement man program.
153 If something strange has gone wrong with your program and you're not
154 sure where you should look for help, try the B<-w> switch first. It
155 will often point out exactly where the trouble is.
159 Perl is a language optimized for scanning arbitrary
160 text files, extracting information from those text files, and printing
161 reports based on that information. It's also a good language for many
162 system management tasks. The language is intended to be practical
163 (easy to use, efficient, complete) rather than beautiful (tiny,
166 Perl combines (in the author's opinion, anyway) some of the best
167 features of C, B<sed>, B<awk>, and B<sh>, so people familiar with
168 those languages should have little difficulty with it. (Language
169 historians will also note some vestiges of B<csh>, Pascal, and even
170 BASIC-PLUS.) Expression syntax corresponds closely to C
171 expression syntax. Unlike most Unix utilities, Perl does not
172 arbitrarily limit the size of your data--if you've got the memory,
173 Perl can slurp in your whole file as a single string. Recursion is of
174 unlimited depth. And the tables used by hashes (sometimes called
175 "associative arrays") grow as necessary to prevent degraded
176 performance. Perl can use sophisticated pattern matching techniques to
177 scan large amounts of data quickly. Although optimized for
178 scanning text, Perl can also deal with binary data, and can make dbm
179 files look like hashes. Setuid Perl scripts are safer than C programs
180 through a dataflow tracing mechanism that prevents many stupid
183 If you have a problem that would ordinarily use B<sed> or B<awk> or
184 B<sh>, but it exceeds their capabilities or must run a little faster,
185 and you don't want to write the silly thing in C, then Perl may be for
186 you. There are also translators to turn your B<sed> and B<awk>
187 scripts into Perl scripts.
189 But wait, there's more...
191 Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete
192 rewrite that provides the following additional benefits:
198 modularity and reusability using innumerable modules
200 Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>.
204 embeddable and extensible
206 Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>,
207 L<perlguts>, and L<xsubpp>.
211 roll-your-own magic variables (including multiple simultaneous DBM implementations)
213 Described in L<perltie> and L<AnyDBM_File>.
217 subroutines can now be overridden, autoloaded, and prototyped
219 Described in L<perlsub>.
223 arbitrarily nested data structures and anonymous functions
225 Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>.
229 object-oriented programming
231 Described in L<perlobj>, L<perltoot>, and L<perlbot>.
235 compilability into C code or Perl bytecode
237 Described in L<B> and L<B::Bytecode>.
241 support for light-weight processes (threads)
243 Described in L<perlthrtut> and L<Thread>.
247 support for internationalization, localization, and Unicode
249 Described in L<perllocale> and L<utf8>.
255 Described in L<perlsub>.
259 regular expression enhancements
261 Described in L<perlre>, with additional examples in L<perlop>.
265 enhanced debugger and interactive Perl environment,
266 with integrated editor support
268 Described in L<perldebug>.
272 POSIX 1003.1 compliant library
274 Described in L<POSIX>.
278 Okay, that's I<definitely> enough hype.
282 Perl is available for most operating systems, including virtually
283 all Unix-like platforms. See L<perlport/"Supported Platforms">
292 Larry Wall <larry@wall.org>, with the help of oodles of other folks.
294 If your Perl success stories and testimonials may be of help to others
295 who wish to advocate the use of Perl in their applications,
296 or if you wish to simply express your gratitude to Larry and the
297 Perl developers, please write to perl-thanks@perl.org .
301 "@INC" locations of perl libraries
305 a2p awk to perl translator
306 s2p sed to perl translator
308 http://www.perl.com/ the Perl Home Page
309 http://www.perl.com/CPAN the Comprehensive Perl Archive
313 The C<use warnings> pragma (and the B<-w> switch) produces some
316 See L<perldiag> for explanations of all Perl's diagnostics. The C<use
317 diagnostics> pragma automatically turns Perl's normally terse warnings
318 and errors into these longer forms.
320 Compilation errors will tell you the line number of the error, with an
321 indication of the next token or token type that was to be examined.
322 (In a script passed to Perl via B<-e> switches, each
323 B<-e> is counted as one line.)
325 Setuid scripts have additional constraints that can produce error
326 messages such as "Insecure dependency". See L<perlsec>.
328 Did we mention that you should definitely consider using the B<-w>
333 The B<-w> switch is not mandatory.
335 Perl is at the mercy of your machine's definitions of various
336 operations such as type casting, atof(), and floating-point
337 output with sprintf().
339 If your stdio requires a seek or eof between reads and writes on a
340 particular stream, so does Perl. (This doesn't apply to sysread()
343 While none of the built-in data types have any arbitrary size limits
344 (apart from memory size), there are still a few arbitrary limits: a
345 given variable name may not be longer than 251 characters. Line numbers
346 displayed by diagnostics are internally stored as short integers,
347 so they are limited to a maximum of 65535 (higher numbers usually being
348 affected by wraparound).
350 You may mail your bug reports (be sure to include full configuration
351 information as output by the myconfig program in the perl source
352 tree, or by C<perl -V>) to perlbug@perl.org . If you've succeeded
353 in compiling perl, the B<perlbug> script in the F<utils/> subdirectory
354 can be used to help mail in a bug report.
356 Perl actually stands for Pathologically Eclectic Rubbish Lister, but
357 don't tell anyone I said that.
361 The Perl motto is "There's more than one way to do it." Divining
362 how many more is left as an exercise to the reader.
364 The three principal virtues of a programmer are Laziness,
365 Impatience, and Hubris. See the Camel Book for why.