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