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 perlmachten Perl notes for Power MachTen
89 perlos2 Perl notes for OS/2
90 perlos390 Perl notes for OS/390
91 perlvms Perl notes for VMS
92 perlwin32 Perl notes for Windows
94 (If you're intending to read these straight through for the first time,
95 the suggested order will tend to reduce the number of forward references.)
97 By default, the manpages listed above are installed in the
98 F</usr/local/man/> directory.
100 Extensive additional documentation for Perl modules is available. The
101 default configuration for perl will place this additional documentation
102 in the F</usr/local/lib/perl5/man> directory (or else in the F<man>
103 subdirectory of the Perl library directory). Some of this additional
104 documentation is distributed standard with Perl, but you'll also find
105 documentation for third-party modules there.
107 You should be able to view Perl's documentation with your man(1)
108 program by including the proper directories in the appropriate start-up
109 files, or in the MANPATH environment variable. To find out where the
110 configuration has installed the manpages, type:
114 If the directories have a common stem, such as F</usr/local/man/man1>
115 and F</usr/local/man/man3>, you need only to add that stem
116 (F</usr/local/man>) to your man(1) configuration files or your MANPATH
117 environment variable. If they do not share a stem, you'll have to add
120 If that doesn't work for some reason, you can still use the
121 supplied F<perldoc> script to view module information. You might
122 also look into getting a replacement man program.
124 If something strange has gone wrong with your program and you're not
125 sure where you should look for help, try the B<-w> switch first. It
126 will often point out exactly where the trouble is.
130 Perl is a language optimized for scanning arbitrary
131 text files, extracting information from those text files, and printing
132 reports based on that information. It's also a good language for many
133 system management tasks. The language is intended to be practical
134 (easy to use, efficient, complete) rather than beautiful (tiny,
137 Perl combines (in the author's opinion, anyway) some of the best
138 features of C, B<sed>, B<awk>, and B<sh>, so people familiar with
139 those languages should have little difficulty with it. (Language
140 historians will also note some vestiges of B<csh>, Pascal, and even
141 BASIC-PLUS.) Expression syntax corresponds closely to C
142 expression syntax. Unlike most Unix utilities, Perl does not
143 arbitrarily limit the size of your data--if you've got the memory,
144 Perl can slurp in your whole file as a single string. Recursion is of
145 unlimited depth. And the tables used by hashes (sometimes called
146 "associative arrays") grow as necessary to prevent degraded
147 performance. Perl can use sophisticated pattern matching techniques to
148 scan large amounts of data quickly. Although optimized for
149 scanning text, Perl can also deal with binary data, and can make dbm
150 files look like hashes. Setuid Perl scripts are safer than C programs
151 through a dataflow tracing mechanism that prevents many stupid
154 If you have a problem that would ordinarily use B<sed> or B<awk> or
155 B<sh>, but it exceeds their capabilities or must run a little faster,
156 and you don't want to write the silly thing in C, then Perl may be for
157 you. There are also translators to turn your B<sed> and B<awk>
158 scripts into Perl scripts.
160 But wait, there's more...
162 Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete
163 rewrite that provides the following additional benefits:
167 =item * modularity and reusability using innumerable modules
169 Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>.
171 =item * embeddable and extensible
173 Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>,
174 L<perlguts>, and L<xsubpp>.
176 =item * roll-your-own magic variables (including multiple simultaneous DBM implementations)
178 Described in L<perltie> and L<AnyDBM_File>.
180 =item * subroutines can now be overridden, autoloaded, and prototyped
182 Described in L<perlsub>.
184 =item * arbitrarily nested data structures and anonymous functions
186 Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>.
188 =item * object-oriented programming
190 Described in L<perlobj>, L<perltoot>, and L<perlbot>.
192 =item * compilability into C code or Perl bytecode
194 Described in L<B> and L<B::Bytecode>.
196 =item * support for light-weight processes (threads)
198 Described in L<perlthrtut> and L<Thread>.
200 =item * support for internationalization, localization, and Unicode
202 Described in L<perllocale> and L<utf8>.
204 =item * lexical scoping
206 Described in L<perlsub>.
208 =item * regular expression enhancements
210 Described in L<perlre>, with additional examples in L<perlop>.
212 =item * enhanced debugger and interactive Perl environment, with integrated editor support
214 Described in L<perldebug>.
216 =item * POSIX 1003.1 compliant library
218 Described in L<POSIX>.
222 Okay, that's I<definitely> enough hype.
226 Perl is available for most operating systems, including virtually
227 all Unix-like platforms. See L<perlport/"Supported Platforms">
236 Larry Wall <larry@wall.org>, with the help of oodles of other folks.
238 If your Perl success stories and testimonials may be of help to others
239 who wish to advocate the use of Perl in their applications,
240 or if you wish to simply express your gratitude to Larry and the
241 Perl developers, please write to perl-thanks@perl.org .
245 "@INC" locations of perl libraries
249 a2p awk to perl translator
250 s2p sed to perl translator
252 http://www.perl.com/ the Perl Home Page
253 http://www.perl.com/CPAN the Comprehensive Perl Archive
257 The C<use warnings> pragma (and the B<-w> switch) produces some
260 See L<perldiag> for explanations of all Perl's diagnostics. The C<use
261 diagnostics> pragma automatically turns Perl's normally terse warnings
262 and errors into these longer forms.
264 Compilation errors will tell you the line number of the error, with an
265 indication of the next token or token type that was to be examined.
266 (In a script passed to Perl via B<-e> switches, each
267 B<-e> is counted as one line.)
269 Setuid scripts have additional constraints that can produce error
270 messages such as "Insecure dependency". See L<perlsec>.
272 Did we mention that you should definitely consider using the B<-w>
277 The B<-w> switch is not mandatory.
279 Perl is at the mercy of your machine's definitions of various
280 operations such as type casting, atof(), and floating-point
281 output with sprintf().
283 If your stdio requires a seek or eof between reads and writes on a
284 particular stream, so does Perl. (This doesn't apply to sysread()
287 While none of the built-in data types have any arbitrary size limits
288 (apart from memory size), there are still a few arbitrary limits: a
289 given variable name may not be longer than 251 characters. Line numbers
290 displayed by diagnostics are internally stored as short integers,
291 so they are limited to a maximum of 65535 (higher numbers usually being
292 affected by wraparound).
294 You may mail your bug reports (be sure to include full configuration
295 information as output by the myconfig program in the perl source
296 tree, or by C<perl -V>) to perlbug@perl.com . If you've succeeded
297 in compiling perl, the B<perlbug> script in the F<utils/> subdirectory
298 can be used to help mail in a bug report.
300 Perl actually stands for Pathologically Eclectic Rubbish Lister, but
301 don't tell anyone I said that.
305 The Perl motto is "There's more than one way to do it." Divining
306 how many more is left as an exercise to the reader.
308 The three principal virtues of a programmer are Laziness,
309 Impatience, and Hubris. See the Camel Book for why.