This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
Add Synology instructions
[perl5.git] / pod / perl.pod
CommitLineData
a0d0e21e
LW
1=head1 NAME
2
095a5c3e 3perl - The Perl 5 language interpreter
a0d0e21e
LW
4
5=head1 SYNOPSIS
6
df451b2a
RGS
7B<perl> S<[ B<-sTtuUWX> ]>
8 S<[ B<-hv> ] [ B<-V>[:I<configvar>] ]>
9 S<[ B<-cw> ] [ B<-d>[B<t>][:I<debugger>] ] [ B<-D>[I<number/list>] ]>
10 S<[ B<-pna> ] [ B<-F>I<pattern> ] [ B<-l>[I<octal>] ] [ B<-0>[I<octal/hexadecimal>] ]>
11 S<[ B<-I>I<dir> ] [ B<-m>[B<->]I<module> ] [ B<-M>[B<->]I<'module...'> ] [ B<-f> ]>
df451b2a 12 S<[ B<-C [I<number/list>] >]>
df451b2a
RGS
13 S<[ B<-S> ]>
14 S<[ B<-x>[I<dir>] ]>
15 S<[ B<-i>[I<extension>] ]>
eb1dd64e 16 S<[ [B<-e>|B<-E>] I<'command'> ] [ B<--> ] [ I<programfile> ] [ I<argument> ]...>
c07a80fd 17
b28fe7ca
JL
18For more information on these options, you can run C<perldoc perlrun>.
19
6b43eec4
DG
20=head1 GETTING HELP
21
22The F<perldoc> program gives you access to all the documentation that comes
23with Perl. You can get more documentation, tutorials and community support
24online at L<http://www.perl.org/>.
25
26If you're new to Perl, you should start by running C<perldoc perlintro>,
27which is a general intro for beginners and provides some background to help
28you navigate the rest of Perl's extensive documentation. Run C<perldoc
29perldoc> to learn more things you can do with F<perldoc>.
10151d09
JH
30
31For ease of access, the Perl manual has been split up into several sections.
a0d0e21e 32
0aef0fe5
NC
33=begin buildtoc
34
35# This section is parsed by Porting/pod_lib.pl for use by pod/buildtoc etc
36
37flag =g perluniprops perlmodlib perlapi perlintern
38flag =go perltoc
39flag =ro perlcn perljp perlko perltw
40flag = perlvms
41
0eb29def
SM
42path perlfaq.* cpan/perlfaq/lib/
43path perlglossary cpan/perlfaq/lib/
44path perlxs(?:tut|typemap)? dist/ExtUtils-ParseXS/lib/
cb1974ba 45path perldoc cpan/Pod-Perldoc/
0aef0fe5
NC
46
47aux a2p c2ph h2ph h2xs perlbug pl2pm pod2html pod2man s2p splain xsubpp
48
49=end buildtoc
50
fd7b6849
MJD
51=head2 Overview
52
fb9cefb4 53 perl Perl overview (this section)
10151d09 54 perlintro Perl introduction for beginners
b28fe7ca 55 perlrun Perl execution and options
fb9cefb4 56 perltoc Perl documentation table of contents
760ac839 57
fd7b6849
MJD
58=head2 Tutorials
59
7a2320f0
AMS
60 perlreftut Perl references short introduction
61 perldsc Perl data structures intro
62 perllol Perl data structures: arrays of arrays
7a2320f0 63
41630250 64 perlrequick Perl regular expressions quick start
7a2320f0
AMS
65 perlretut Perl regular expressions tutorial
66
82e1c0d9 67 perlootut Perl OO tutorial for beginners
7a2320f0 68
da096611
RGS
69 perlperf Perl Performance and Optimization Techniques
70
7a2320f0
AMS
71 perlstyle Perl style guide
72
41630250 73 perlcheat Perl cheat sheet
7a2320f0
AMS
74 perltrap Perl traps for the unwary
75 perldebtut Perl debugging tutorial
76
fd7b6849
MJD
77 perlfaq Perl frequently asked questions
78 perlfaq1 General Questions About Perl
79 perlfaq2 Obtaining and Learning about Perl
80 perlfaq3 Programming Tools
81 perlfaq4 Data Manipulation
82 perlfaq5 Files and Formats
83 perlfaq6 Regexes
84 perlfaq7 Perl Language Issues
85 perlfaq8 System Interaction
86 perlfaq9 Networking
0f542199 87
fd7b6849 88=head2 Reference Manual
413510b3 89
fb9cefb4 90 perlsyn Perl syntax
4755096e 91 perldata Perl data structures
fb9cefb4 92 perlop Perl operators and precedence
c2e66d9e 93 perlsub Perl subroutines
fd7b6849 94 perlfunc Perl built-in functions
413510b3 95 perlopentut Perl open() tutorial
41630250 96 perlpacktut Perl pack() and unpack() tutorial
c2e66d9e 97 perlpod Perl plain old documentation
41630250 98 perlpodspec Perl plain old documentation format specification
f4d47668 99 perlpodstyle Perl POD style guide
c2e66d9e 100 perldiag Perl diagnostic messages
41630250 101 perllexwarn Perl warnings and their control
4755096e 102 perldebug Perl debugging
fb9cefb4 103 perlvar Perl predefined variables
4755096e 104 perlre Perl regular expressions, the rest of the story
8a118206
RGS
105 perlrebackslash Perl regular expression backslash sequences
106 perlrecharclass Perl regular expression character classes
30487ceb 107 perlreref Perl regular expressions quick reference
d396a558 108 perlref Perl references, the rest of the story
fb9cefb4 109 perlform Perl formats
d396a558 110 perlobj Perl objects
d396a558 111 perltie Perl objects hidden behind simple variables
fd7b6849 112 perldbmfilter Perl DBM filters
760ac839 113
c2e66d9e
GS
114 perlipc Perl interprocess communication
115 perlfork Perl fork() information
116 perlnumber Perl number semantics
53d7eaa8 117
c2e66d9e
GS
118 perlthrtut Perl threads tutorial
119
120 perlport Perl portability guide
d396a558 121 perllocale Perl locale support
07fcf8ff 122 perluniintro Perl Unicode introduction
41630250 123 perlunicode Perl Unicode support
3426ea3d 124 perlunifaq Perl Unicode FAQ
0cb5a9a8 125 perluniprops Index of Unicode properties in Perl
aadaa455 126 perlunitut Perl Unicode tutorial
d396a558 127 perlebcdic Considerations for running Perl on EBCDIC platforms
c2e66d9e 128
d396a558 129 perlsec Perl security
4755096e 130
c2e66d9e 131 perlmod Perl modules: how they work
35bf961c
JH
132 perlmodlib Perl modules: how to write and use
133 perlmodstyle Perl modules: how to write modules with style
fd7b6849 134 perlmodinstall Perl modules: how to install from CPAN
c2e66d9e 135 perlnewmod Perl modules: preparing a new module for distribution
a550ee30 136 perlpragma Perl modules: writing a user pragma
760ac839 137
fd7b6849 138 perlutil utilities packaged with the Perl distribution
760ac839 139
fd7b6849
MJD
140 perlfilter Perl source filters
141
4000c4db
FC
142 perldtrace Perl's support for DTrace
143
97a1d740
YST
144 perlglossary Perl Glossary
145
fd7b6849
MJD
146=head2 Internals and C Language Interface
147
fb9cefb4 148 perlembed Perl ways to embed perl in your C or C++ application
41630250 149 perldebguts Perl debugging guts and tips
fb9cefb4 150 perlxstut Perl XS tutorial
4755096e 151 perlxs Perl XS application programming interface
0eb29def 152 perlxstypemap Perl XS C/Perl type conversion tools
f40a6c71 153 perlclib Internal replacements for standard C library functions
fb9cefb4
GS
154 perlguts Perl internal functions for those doing extensions
155 perlcall Perl calling conventions from C
15932acc 156 perlmroapi Perl method resolution plugin interface
108003db 157 perlreapi Perl regular expression plugin interface
b23a565d 158 perlreguts Perl regular expression engine internals
fd7b6849 159
954c1994
GS
160 perlapi Perl API listing (autogenerated)
161 perlintern Perl internal functions (autogenerated)
dc5c060f 162 perliol C API for Perl's implementation of IO in Layers
4755096e 163 perlapio Perl internal IO abstraction interface
fd7b6849 164
e8cd7eae 165 perlhack Perl hackers guide
04c692a8 166 perlsource Guide to the Perl source tree
1c2e8cca 167 perlinterp Overview of the Perl interpreter source and how it works
04c692a8
DR
168 perlhacktut Walk through the creation of a simple C code patch
169 perlhacktips Tips for Perl core C code hacking
cb8a010e 170 perlpolicy Perl development policies
04c692a8 171 perlgit Using git with the Perl repository
4755096e 172
fd7b6849
MJD
173=head2 Miscellaneous
174
175 perlbook Perl book information
cbd87e7e 176 perlcommunity Perl community information
fd7b6849 177
2a551100
JH
178 perldoc Look up Perl documentation in Pod format
179
fb9cefb4 180 perlhist Perl history records
bdfb6cc8 181 perldelta Perl changes since previous version
28ee95bc 182 perl5195delta Perl changes in version 5.19.5
09f4604f 183 perl5194delta Perl changes in version 5.19.4
ba03bc34 184 perl5193delta Perl changes in version 5.19.3
12dcbffb 185 perl5192delta Perl changes in version 5.19.2
38663f11 186 perl5191delta Perl changes in version 5.19.1
583aa5c2 187 perl5190delta Perl changes in version 5.19.0
f4e35152 188 perl5181delta Perl changes in version 5.18.1
f13a3008 189 perl5180delta Perl changes in version 5.18.0
69cb649c 190 perl5161delta Perl changes in version 5.16.1
50f27400 191 perl5162delta Perl changes in version 5.16.2
eaf7bcbf 192 perl5163delta Perl changes in version 5.16.3
05c8f9ed 193 perl5160delta Perl changes in version 5.16.0
1e5cc764 194 perl5144delta Perl changes in version 5.14.4
70ce046e 195 perl5143delta Perl changes in version 5.14.3
77efd0f7 196 perl5142delta Perl changes in version 5.14.2
10288c7a 197 perl5141delta Perl changes in version 5.14.1
066dc4d9 198 perl5140delta Perl changes in version 5.14.0
a5caed3e 199 perl5125delta Perl changes in version 5.12.5
0b67f426 200 perl5124delta Perl changes in version 5.12.4
6c5f5efa 201 perl5123delta Perl changes in version 5.12.3
e71d1a7d 202 perl5122delta Perl changes in version 5.12.2
bdfb6cc8 203 perl5121delta Perl changes in version 5.12.1
20d57231 204 perl5120delta Perl changes in version 5.12.0
7cdf958d 205 perl5101delta Perl changes in version 5.10.1
7120b314 206 perl5100delta Perl changes in version 5.10.0
fc5be808 207 perl589delta Perl changes in version 5.8.9
c11a53c6 208 perl588delta Perl changes in version 5.8.8
315ba985 209 perl587delta Perl changes in version 5.8.7
e4bb216d 210 perl586delta Perl changes in version 5.8.6
07e9b5fe 211 perl585delta Perl changes in version 5.8.5
5f15c94e 212 perl584delta Perl changes in version 5.8.4
2e038148
NC
213 perl583delta Perl changes in version 5.8.3
214 perl582delta Perl changes in version 5.8.2
b6235c4f 215 perl581delta Perl changes in version 5.8.1
2e038148 216 perl58delta Perl changes in version 5.8.0
493a87da 217 perl561delta Perl changes in version 5.6.1
41630250 218 perl56delta Perl changes in version 5.6
4755096e
GS
219 perl5005delta Perl changes in version 5.005
220 perl5004delta Perl changes in version 5.004
d516a115 221
42e73e1c 222 perlexperiment A listing of experimental features in Perl
223
2a551100
JH
224 perlartistic Perl Artistic License
225 perlgpl GNU General Public License
226
d8416318
JH
227=head2 Language-Specific
228
0aef0fe5
NC
229=for buildtoc flag +r
230
d8416318
JH
231 perlcn Perl for Simplified Chinese (in EUC-CN)
232 perljp Perl for Japanese (in EUC-JP)
233 perlko Perl for Korean (in EUC-KR)
234 perltw Perl for Traditional Chinese (in Big5)
235
fd7b6849
MJD
236=head2 Platform-Specific
237
37d4d706 238 perlaix Perl notes for AIX
a83b6f46 239 perlamiga Perl notes for AmigaOS
dc5c060f 240 perlbs2000 Perl notes for POSIX-BC BS2000
a1f19229 241 perlce Perl notes for WinCE
49877630
GS
242 perlcygwin Perl notes for Cygwin
243 perldos Perl notes for DOS
41630250 244 perlfreebsd Perl notes for FreeBSD
f6706af3 245 perlhaiku Perl notes for Haiku
49877630 246 perlhpux Perl notes for HP-UX
a83b6f46 247 perlhurd Perl notes for Hurd
469e7be4 248 perlirix Perl notes for Irix
991e8403 249 perllinux Perl notes for Linux
26d9b02f 250 perlmacos Perl notes for Mac OS (Classic)
0d53b15f 251 perlmacosx Perl notes for Mac OS X
41630250 252 perlnetware Perl notes for NetWare
b0846812 253 perlopenbsd Perl notes for OpenBSD
49877630
GS
254 perlos2 Perl notes for OS/2
255 perlos390 Perl notes for OS/390
522b859a 256 perlos400 Perl notes for OS/400
a83b6f46
JH
257 perlplan9 Perl notes for Plan 9
258 perlqnx Perl notes for QNX
2f08ed66 259 perlriscos Perl notes for RISC OS
d420ca49 260 perlsolaris Perl notes for Solaris
27da23d5 261 perlsymbian Perl notes for Symbian
58534900 262 perlsynology Perl notes for Synology
772ff3b9 263 perltru64 Perl notes for Tru64
49877630 264 perlvms Perl notes for VMS
9a997319 265 perlvos Perl notes for Stratus VOS
49877630
GS
266 perlwin32 Perl notes for Windows
267
0aef0fe5
NC
268=for buildtoc flag -r
269
e653ab25
DR
270=head2 Stubs for Deleted Documents
271
272 perlboot
273 perlbot
9ab63835 274 perlrepository
5d0b49e8 275 perltodo
e653ab25
DR
276 perltooc
277 perltoot
278
0aef0fe5 279=for buildtoc __END__
35dec5db 280
6b43eec4
DG
281On a Unix-like system, these documentation files will usually also be
282available as manpages for use with the F<man> program.
a0d0e21e 283
f747cd2a
MB
284Some documentation is not available as man pages, so if a
285cross-reference is not found by man, try it with L<perldoc>. Perldoc can
286also take you directly to documentation for functions (with the B<-f>
287switch). See C<perldoc --help> (or C<perldoc perldoc> or C<man perldoc>)
288for other helpful options L<perldoc> has to offer.
289
6b43eec4 290In general, if something strange has gone wrong with your program and you're
71b5b092
SF
291not sure where you should look for help, try making your code comply with
292B<use strict> and B<use warnings>. These will often point out exactly
293where the trouble is.
a0d0e21e
LW
294
295=head1 DESCRIPTION
296
d27f2b2f
DG
297Perl officially stands for Practical Extraction and Report Language,
298except when it doesn't.
299
72033c14 300Perl was originally a language optimized for scanning arbitrary
a0d0e21e 301text files, extracting information from those text files, and printing
72033c14
JV
302reports based on that information. It quickly became a good language
303for many system management tasks. Over the years, Perl has grown into
b6538e4f 304a general-purpose programming language. It's widely used for everything
72033c14
JV
305from quick "one-liners" to full-scale application development.
306
307The language is intended to be practical (easy to use, efficient,
c1264fa8
RS
308complete) rather than beautiful (tiny, elegant, minimal). It combines
309(in the author's opinion, anyway) some of the best features of B<sed>,
0e7bd06d 310B<awk>, and B<sh>, making it familiar and easy to use for Unix users to
c1264fa8
RS
311whip up quick solutions to annoying problems. Its general-purpose
312programming facilities support procedural, functional, and
313object-oriented programming paradigms, making Perl a comfortable
314language for the long haul on major projects, whatever your bent.
315
316Perl's roots in text processing haven't been forgotten over the years.
317It still boasts some of the most powerful regular expressions to be
318found anywhere, and its support for Unicode text is world-class. It
319handles all kinds of structured text, too, through an extensive
320collection of extensions. Those libraries, collected in the CPAN,
321provide ready-made solutions to an astounding array of problems. When
322they haven't set the standard themselves, they steal from the best
323-- just like Perl itself.
a0d0e21e 324
8e465e4e
JH
325=head1 AVAILABILITY
326
14218588 327Perl is available for most operating systems, including virtually
055fd3a9
GS
328all Unix-like platforms. See L<perlport/"Supported Platforms">
329for a listing.
8bc4a6bb 330
a0d0e21e
LW
331=head1 ENVIRONMENT
332
1e422769 333See L<perlrun>.
a0d0e21e
LW
334
335=head1 AUTHOR
336
19799a22 337Larry Wall <larry@wall.org>, with the help of oodles of other folks.
a0d0e21e 338
a99b1639
TP
339If your Perl success stories and testimonials may be of help to others
340who wish to advocate the use of Perl in their applications,
341or if you wish to simply express your gratitude to Larry and the
19799a22 342Perl developers, please write to perl-thanks@perl.org .
a99b1639 343
a0d0e21e
LW
344=head1 FILES
345
5f05dabc 346 "@INC" locations of perl libraries
a0d0e21e
LW
347
348=head1 SEE ALSO
349
c5f69108 350 http://www.perl.org/ the Perl homepage
da9e6348 351 http://www.perl.com/ Perl articles (O'Reilly)
f6b3c421 352 http://www.cpan.org/ the Comprehensive Perl Archive
c5f69108 353 http://www.pm.org/ the Perl Mongers
19799a22 354
a0d0e21e
LW
355=head1 DIAGNOSTICS
356
71b5b092
SF
357Using the C<use strict> pragma ensures that all variables are properly
358declared and prevents other misuses of legacy Perl features.
359
6753a9e9
SF
360The C<use warnings> pragma produces some lovely diagnostics. One can
361also use the B<-w> flag, but its use is normally discouraged, because
362it gets applied to all executed Perl code, including that not under
363your control.
a0d0e21e 364
5a964f20
TC
365See L<perldiag> for explanations of all Perl's diagnostics. The C<use
366diagnostics> pragma automatically turns Perl's normally terse warnings
367and errors into these longer forms.
a0d0e21e
LW
368
369Compilation errors will tell you the line number of the error, with an
370indication of the next token or token type that was to be examined.
14218588 371(In a script passed to Perl via B<-e> switches, each
a0d0e21e
LW
372B<-e> is counted as one line.)
373
374Setuid scripts have additional constraints that can produce error
375messages such as "Insecure dependency". See L<perlsec>.
376
71b5b092
SF
377Did we mention that you should definitely consider using the B<use warnings>
378pragma?
a0d0e21e
LW
379
380=head1 BUGS
381
71b5b092 382The behavior implied by the B<use warnings> pragma is not mandatory.
a0d0e21e
LW
383
384Perl is at the mercy of your machine's definitions of various
1b3f7d21
CS
385operations such as type casting, atof(), and floating-point
386output with sprintf().
a0d0e21e 387
748a9306 388If your stdio requires a seek or eof between reads and writes on a
a0d0e21e
LW
389particular stream, so does Perl. (This doesn't apply to sysread()
390and syswrite().)
391
392While none of the built-in data types have any arbitrary size limits
393(apart from memory size), there are still a few arbitrary limits: a
a30ac152
GS
394given variable name may not be longer than 251 characters. Line numbers
395displayed by diagnostics are internally stored as short integers,
396so they are limited to a maximum of 65535 (higher numbers usually being
397affected by wraparound).
a0d0e21e 398
b0607b7a 399You may mail your bug reports (be sure to include full configuration
19799a22 400information as output by the myconfig program in the perl source
7f2de2d2 401tree, or by C<perl -V>) to perlbug@perl.org . If you've succeeded
7f89f796 402in compiling perl, the L<perlbug> script in the F<utils/> subdirectory
19799a22 403can be used to help mail in a bug report.
4633a7c4 404
a0d0e21e
LW
405Perl actually stands for Pathologically Eclectic Rubbish Lister, but
406don't tell anyone I said that.
407
408=head1 NOTES
409
410The Perl motto is "There's more than one way to do it." Divining
411how many more is left as an exercise to the reader.
412
4633a7c4 413The three principal virtues of a programmer are Laziness,
a0d0e21e 414Impatience, and Hubris. See the Camel Book for why.
16d20bd9 415