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 perldebug Perl debugging
54 perldiag Perl diagnostic messages
56 perltrap Perl traps for the unwary
57 perlport Perl portability guide
58 perlstyle Perl style guide
60 perlpod Perl plain old documentation
61 perlbook Perl book information
63 perlembed Perl ways to embed perl in your C or C++ application
64 perlapio Perl internal IO abstraction interface
65 perlxs Perl XS application programming interface
66 perlxstut Perl XS tutorial
67 perlguts Perl internal functions for those doing extensions
68 perlcall Perl calling conventions from C
70 perltodo Perl things to do
71 perlhist Perl history records
73 (If you're intending to read these straight through for the first time,
74 the suggested order will tend to reduce the number of forward references.)
76 By default, the manpages listed above are installed in the
77 F</usr/local/man/> directory.
79 Extensive additional documentation for Perl modules is available. The
80 default configuration for perl will place this additional documentation
81 in the F</usr/local/lib/perl5/man> directory (or else in the F<man>
82 subdirectory of the Perl library directory). Some of this additional
83 documentation is distributed standard with Perl, but you'll also find
84 documentation for third-party modules there.
86 You should be able to view Perl's documentation with your man(1)
87 program by including the proper directories in the appropriate start-up
88 files, or in the MANPATH environment variable. To find out where the
89 configuration has installed the manpages, type:
93 If the directories have a common stem, such as F</usr/local/man/man1>
94 and F</usr/local/man/man3>, you need only to add that stem
95 (F</usr/local/man>) to your man(1) configuration files or your MANPATH
96 environment variable. If they do not share a stem, you'll have to add
99 If that doesn't work for some reason, you can still use the
100 supplied F<perldoc> script to view module information. You might
101 also look into getting a replacement man program.
103 If something strange has gone wrong with your program and you're not
104 sure where you should look for help, try the B<-w> switch first. It
105 will often point out exactly where the trouble is.
109 Perl is a language optimized for scanning arbitrary
110 text files, extracting information from those text files, and printing
111 reports based on that information. It's also a good language for many
112 system management tasks. The language is intended to be practical
113 (easy to use, efficient, complete) rather than beautiful (tiny,
116 Perl combines (in the author's opinion, anyway) some of the best
117 features of C, B<sed>, B<awk>, and B<sh>, so people familiar with
118 those languages should have little difficulty with it. (Language
119 historians will also note some vestiges of B<csh>, Pascal, and even
120 BASIC-PLUS.) Expression syntax corresponds closely to C
121 expression syntax. Unlike most Unix utilities, Perl does not
122 arbitrarily limit the size of your data--if you've got the memory,
123 Perl can slurp in your whole file as a single string. Recursion is of
124 unlimited depth. And the tables used by hashes (sometimes called
125 "associative arrays") grow as necessary to prevent degraded
126 performance. Perl can use sophisticated pattern matching techniques to
127 scan large amounts of data quickly. Although optimized for
128 scanning text, Perl can also deal with binary data, and can make dbm
129 files look like hashes. Setuid Perl scripts are safer than C programs
130 through a dataflow tracing mechanism that prevents many stupid
133 If you have a problem that would ordinarily use B<sed> or B<awk> or
134 B<sh>, but it exceeds their capabilities or must run a little faster,
135 and you don't want to write the silly thing in C, then Perl may be for
136 you. There are also translators to turn your B<sed> and B<awk>
137 scripts into Perl scripts.
139 But wait, there's more...
141 Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete
142 rewrite that provides the following additional benefits:
146 =item * modularity and reusability using innumerable modules
148 Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>.
150 =item * embeddable and extensible
152 Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>,
153 L<perlguts>, and L<xsubpp>.
155 =item * roll-your-own magic variables (including multiple simultaneous DBM implementations)
157 Described in L<perltie> and L<AnyDBM_File>.
159 =item * subroutines can now be overridden, autoloaded, and prototyped
161 Described in L<perlsub>.
163 =item * arbitrarily nested data structures and anonymous functions
165 Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>.
167 =item * object-oriented programming
169 Described in L<perlobj>, L<perltoot>, and L<perlbot>.
171 =item * compilability into C code or Perl bytecode
173 Described in L<B> and L<B::Bytecode>.
175 =item * support for light-weight processes (threads)
177 Described in L<perlthrtut> and L<Thread>.
179 =item * support for internationalization, localization, and Unicode
181 Described in L<perllocale> and L<utf8>.
183 =item * lexical scoping
185 Described in L<perlsub>.
187 =item * regular expression enhancements
189 Described in L<perlre>, with additional examples in L<perlop>.
191 =item * enhanced debugger and interactive Perl environment, with integrated editor support
193 Described in L<perldebug>.
195 =item * POSIX 1003.1 compliant library
197 Described in L<POSIX>.
201 Okay, that's I<definitely> enough hype.
205 Perl is available for most operating systems, including virtually
206 all Unix-like platforms.
208 As of May 1999, the following platforms are able to build Perl
209 from the standard source code distribution available at
210 http://www.perl.com/CPAN/src/index.html
212 AIX Linux SCO ODT/OSR
216 DG/UX NextSTEP Tru64 UNIX 3)
217 DomainOS OpenBSD Ultrix
218 DOS DJGPP 1) OpenSTEP UNICOS
221 HP-UX PowerMAX Windows 3.1 1)
222 Hurd QNX Windows 95 1) 4)
223 IRIX Windows 98 1) 4)
226 1) in DOS mode either the DOS or OS/2 ports can be used
227 2) formerly known as MVS
228 3) formerly known as Digital UNIX and before that DEC OSF/1
229 4) compilers: Borland, Cygwin32, Mingw32 EGCS/GCC, VC++
231 The following platforms have been known to build Perl from source,
232 but we haven't been able to verify their status for the current release,
233 either because the hardware/software platforms are rare or
234 because we don't have an active champion on these platforms--or both.
237 AmigaOS GENIX PowerUX
238 ConvexOS Greenhills RISC/os
240 DC/OSx MachTen 68k SVR2
243 Dynix NEWS-OS UNICOS/mk
244 EP/IX Opus Unisys Dynix
247 Support for the following platforms is planned for the next major
255 The following platforms have their own source code distributions and
256 binaries available via http://www.perl.com/CPAN/ports/index.html.
263 Tandem Guardian 5.004
265 The following platforms have only binaries available via
266 http://www.perl.com/CPAN/ports/index.html.
270 Acorn RISCOS 5.005_02
280 Larry Wall <larry@wall.org>, with the help of oodles of other folks.
282 If your Perl success stories and testimonials may be of help to others
283 who wish to advocate the use of Perl in their applications,
284 or if you wish to simply express your gratitude to Larry and the
285 Perl developers, please write to perl-thanks@perl.org .
289 "@INC" locations of perl libraries
293 a2p awk to perl translator
294 s2p sed to perl translator
296 http://www.perl.com/ the Perl Home Page
297 http://www.perl.com/CPAN the Comphrehensive Perl Archive
301 The B<-w> switch produces some lovely diagnostics.
303 See L<perldiag> for explanations of all Perl's diagnostics. The C<use
304 diagnostics> pragma automatically turns Perl's normally terse warnings
305 and errors into these longer forms.
307 Compilation errors will tell you the line number of the error, with an
308 indication of the next token or token type that was to be examined.
309 (In a script passed to Perl via B<-e> switches, each
310 B<-e> is counted as one line.)
312 Setuid scripts have additional constraints that can produce error
313 messages such as "Insecure dependency". See L<perlsec>.
315 Did we mention that you should definitely consider using the B<-w>
320 The B<-w> switch is not mandatory.
322 Perl is at the mercy of your machine's definitions of various
323 operations such as type casting, atof(), and floating-point
324 output with sprintf().
326 If your stdio requires a seek or eof between reads and writes on a
327 particular stream, so does Perl. (This doesn't apply to sysread()
330 While none of the built-in data types have any arbitrary size limits
331 (apart from memory size), there are still a few arbitrary limits: a
332 given variable name may not be longer than 251 characters. Line numbers
333 displayed by diagnostics are internally stored as short integers,
334 so they are limited to a maximum of 65535 (higher numbers usually being
335 affected by wraparound).
337 You may mail your bug reports (be sure to include full configuration
338 information as output by the myconfig program in the perl source
339 tree, or by C<perl -V>) to perlbug@perl.com . If you've succeeded
340 in compiling perl, the perlbug script in the utils/ subdirectory
341 can be used to help mail in a bug report.
343 Perl actually stands for Pathologically Eclectic Rubbish Lister, but
344 don't tell anyone I said that.
348 The Perl motto is "There's more than one way to do it." Divining
349 how many more is left as an exercise to the reader.
351 The three principal virtues of a programmer are Laziness,
352 Impatience, and Hubris. See the Camel Book for why.