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