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