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 perllocale Perl locale support
40 perlreftut Perl references short introduction
41 perlref Perl references, the rest of the story
42 perldsc Perl data structures intro
43 perllol Perl data structures: arrays of arrays
44 perltoot Perl OO tutorial, part 1
45 perltootc Perl OO tutorial, part 2
47 perltie Perl objects hidden behind simple variables
48 perlbot Perl OO tricks and examples
49 perlipc Perl interprocess communication
50 perlthrtut Perl threads tutorial
51 perldbmfilter Perl DBM Filters
53 perlcompile Perl compiler suite intro
54 perldebug Perl debugging
55 perldiag Perl diagnostic messages
57 perltrap Perl traps for the unwary
58 perlport Perl portability guide
59 perlstyle Perl style guide
61 perlpod Perl plain old documentation
62 perlbook Perl book information
64 perlembed Perl ways to embed perl in your C or C++ application
65 perlapio Perl internal IO abstraction interface
66 perlxs Perl XS application programming interface
67 perlxstut Perl XS tutorial
68 perlguts Perl internal functions for those doing extensions
69 perlcall Perl calling conventions from C
71 perltodo Perl things to do
72 perlhack Perl hackers guide
73 perlhist Perl history records
75 (If you're intending to read these straight through for the first time,
76 the suggested order will tend to reduce the number of forward references.)
78 By default, the manpages listed above are installed in the
79 F</usr/local/man/> directory.
81 Extensive additional documentation for Perl modules is available. The
82 default configuration for perl will place this additional documentation
83 in the F</usr/local/lib/perl5/man> directory (or else in the F<man>
84 subdirectory of the Perl library directory). Some of this additional
85 documentation is distributed standard with Perl, but you'll also find
86 documentation for third-party modules there.
88 You should be able to view Perl's documentation with your man(1)
89 program by including the proper directories in the appropriate start-up
90 files, or in the MANPATH environment variable. To find out where the
91 configuration has installed the manpages, type:
95 If the directories have a common stem, such as F</usr/local/man/man1>
96 and F</usr/local/man/man3>, you need only to add that stem
97 (F</usr/local/man>) to your man(1) configuration files or your MANPATH
98 environment variable. If they do not share a stem, you'll have to add
101 If that doesn't work for some reason, you can still use the
102 supplied F<perldoc> script to view module information. You might
103 also look into getting a replacement man program.
105 If something strange has gone wrong with your program and you're not
106 sure where you should look for help, try the B<-w> switch first. It
107 will often point out exactly where the trouble is.
111 Perl is a language optimized for scanning arbitrary
112 text files, extracting information from those text files, and printing
113 reports based on that information. It's also a good language for many
114 system management tasks. The language is intended to be practical
115 (easy to use, efficient, complete) rather than beautiful (tiny,
118 Perl combines (in the author's opinion, anyway) some of the best
119 features of C, B<sed>, B<awk>, and B<sh>, so people familiar with
120 those languages should have little difficulty with it. (Language
121 historians will also note some vestiges of B<csh>, Pascal, and even
122 BASIC-PLUS.) Expression syntax corresponds closely to C
123 expression syntax. Unlike most Unix utilities, Perl does not
124 arbitrarily limit the size of your data--if you've got the memory,
125 Perl can slurp in your whole file as a single string. Recursion is of
126 unlimited depth. And the tables used by hashes (sometimes called
127 "associative arrays") grow as necessary to prevent degraded
128 performance. Perl can use sophisticated pattern matching techniques to
129 scan large amounts of data quickly. Although optimized for
130 scanning text, Perl can also deal with binary data, and can make dbm
131 files look like hashes. Setuid Perl scripts are safer than C programs
132 through a dataflow tracing mechanism that prevents many stupid
135 If you have a problem that would ordinarily use B<sed> or B<awk> or
136 B<sh>, but it exceeds their capabilities or must run a little faster,
137 and you don't want to write the silly thing in C, then Perl may be for
138 you. There are also translators to turn your B<sed> and B<awk>
139 scripts into Perl scripts.
141 But wait, there's more...
143 Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete
144 rewrite that provides the following additional benefits:
148 =item * modularity and reusability using innumerable modules
150 Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>.
152 =item * embeddable and extensible
154 Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>,
155 L<perlguts>, and L<xsubpp>.
157 =item * roll-your-own magic variables (including multiple simultaneous DBM implementations)
159 Described in L<perltie> and L<AnyDBM_File>.
161 =item * subroutines can now be overridden, autoloaded, and prototyped
163 Described in L<perlsub>.
165 =item * arbitrarily nested data structures and anonymous functions
167 Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>.
169 =item * object-oriented programming
171 Described in L<perlobj>, L<perltoot>, and L<perlbot>.
173 =item * compilability into C code or Perl bytecode
175 Described in L<B> and L<B::Bytecode>.
177 =item * support for light-weight processes (threads)
179 Described in L<perlthrtut> and L<Thread>.
181 =item * support for internationalization, localization, and Unicode
183 Described in L<perllocale> and L<utf8>.
185 =item * lexical scoping
187 Described in L<perlsub>.
189 =item * regular expression enhancements
191 Described in L<perlre>, with additional examples in L<perlop>.
193 =item * enhanced debugger and interactive Perl environment, with integrated editor support
195 Described in L<perldebug>.
197 =item * POSIX 1003.1 compliant library
199 Described in L<POSIX>.
203 Okay, that's I<definitely> enough hype.
207 Perl is available for most operating systems, including virtually
208 all Unix-like platforms.
210 As of May 1999, the following platforms are able to build Perl
211 from the standard source code distribution available at
212 http://www.perl.com/CPAN/src/index.html
214 AIX Linux SCO ODT/OSR
218 DG/UX NextSTEP Tru64 UNIX 3)
219 DomainOS OpenBSD Ultrix
220 DOS DJGPP 1) OpenSTEP UNICOS
223 HP-UX PowerMAX Windows 3.1 1)
224 Hurd QNX Windows 95 1) 4)
225 IRIX Windows 98 1) 4)
228 1) in DOS mode either the DOS or OS/2 ports can be used
229 2) formerly known as MVS
230 3) formerly known as Digital UNIX and before that DEC OSF/1
231 4) compilers: Borland, Cygwin, Mingw32 EGCS/GCC, VC++
233 The following platforms have been known to build Perl from source,
234 but we haven't been able to verify their status for the current release,
235 either because the hardware/software platforms are rare or
236 because we don't have an active champion on these platforms--or both.
239 AmigaOS GENIX PowerUX
240 ConvexOS Greenhills RISC/os
242 DC/OSx MachTen 68k SVR2
245 Dynix NEWS-OS UNICOS/mk
246 EP/IX Opus Unisys Dynix
249 Support for the following platforms is planned for the next major
257 The following platforms have their own source code distributions and
258 binaries available via http://www.perl.com/CPAN/ports/index.html.
265 Tandem Guardian 5.004
267 The following platforms have only binaries available via
268 http://www.perl.com/CPAN/ports/index.html.
272 Acorn RISCOS 5.005_02
282 Larry Wall <larry@wall.org>, with the help of oodles of other folks.
284 If your Perl success stories and testimonials may be of help to others
285 who wish to advocate the use of Perl in their applications,
286 or if you wish to simply express your gratitude to Larry and the
287 Perl developers, please write to perl-thanks@perl.org .
291 "@INC" locations of perl libraries
295 a2p awk to perl translator
296 s2p sed to perl translator
298 http://www.perl.com/ the Perl Home Page
299 http://www.perl.com/CPAN the Comphrehensive Perl Archive
303 The B<-w> switch produces some lovely diagnostics.
305 See L<perldiag> for explanations of all Perl's diagnostics. The C<use
306 diagnostics> pragma automatically turns Perl's normally terse warnings
307 and errors into these longer forms.
309 Compilation errors will tell you the line number of the error, with an
310 indication of the next token or token type that was to be examined.
311 (In a script passed to Perl via B<-e> switches, each
312 B<-e> is counted as one line.)
314 Setuid scripts have additional constraints that can produce error
315 messages such as "Insecure dependency". See L<perlsec>.
317 Did we mention that you should definitely consider using the B<-w>
322 The B<-w> switch is not mandatory.
324 Perl is at the mercy of your machine's definitions of various
325 operations such as type casting, atof(), and floating-point
326 output with sprintf().
328 If your stdio requires a seek or eof between reads and writes on a
329 particular stream, so does Perl. (This doesn't apply to sysread()
332 While none of the built-in data types have any arbitrary size limits
333 (apart from memory size), there are still a few arbitrary limits: a
334 given variable name may not be longer than 251 characters. Line numbers
335 displayed by diagnostics are internally stored as short integers,
336 so they are limited to a maximum of 65535 (higher numbers usually being
337 affected by wraparound).
339 You may mail your bug reports (be sure to include full configuration
340 information as output by the myconfig program in the perl source
341 tree, or by C<perl -V>) to perlbug@perl.com . If you've succeeded
342 in compiling perl, the perlbug script in the utils/ subdirectory
343 can be used to help mail in a bug report.
345 Perl actually stands for Pathologically Eclectic Rubbish Lister, but
346 don't tell anyone I said that.
350 The Perl motto is "There's more than one way to do it." Divining
351 how many more is left as an exercise to the reader.
353 The three principal virtues of a programmer are Laziness,
354 Impatience, and Hubris. See the Camel Book for why.