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