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