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