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