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