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