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