This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
New perldelta
[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 46
c67aee7a 47aux c2ph h2ph h2xs perlbug pl2pm pod2html pod2man splain xsubpp
0aef0fe5
NC
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
5dd47fd4 124 perlunicook Perl Unicode cookbook
3426ea3d 125 perlunifaq Perl Unicode FAQ
0cb5a9a8 126 perluniprops Index of Unicode properties in Perl
aadaa455 127 perlunitut Perl Unicode tutorial
d396a558 128 perlebcdic Considerations for running Perl on EBCDIC platforms
c2e66d9e 129
d396a558 130 perlsec Perl security
4755096e 131
c2e66d9e 132 perlmod Perl modules: how they work
35bf961c
JH
133 perlmodlib Perl modules: how to write and use
134 perlmodstyle Perl modules: how to write modules with style
fd7b6849 135 perlmodinstall Perl modules: how to install from CPAN
c2e66d9e 136 perlnewmod Perl modules: preparing a new module for distribution
a550ee30 137 perlpragma Perl modules: writing a user pragma
760ac839 138
fd7b6849 139 perlutil utilities packaged with the Perl distribution
760ac839 140
fd7b6849
MJD
141 perlfilter Perl source filters
142
4000c4db
FC
143 perldtrace Perl's support for DTrace
144
97a1d740
YST
145 perlglossary Perl Glossary
146
fd7b6849
MJD
147=head2 Internals and C Language Interface
148
fb9cefb4 149 perlembed Perl ways to embed perl in your C or C++ application
41630250 150 perldebguts Perl debugging guts and tips
fb9cefb4 151 perlxstut Perl XS tutorial
4755096e 152 perlxs Perl XS application programming interface
0eb29def 153 perlxstypemap Perl XS C/Perl type conversion tools
f40a6c71 154 perlclib Internal replacements for standard C library functions
fb9cefb4
GS
155 perlguts Perl internal functions for those doing extensions
156 perlcall Perl calling conventions from C
15932acc 157 perlmroapi Perl method resolution plugin interface
108003db 158 perlreapi Perl regular expression plugin interface
b23a565d 159 perlreguts Perl regular expression engine internals
fd7b6849 160
954c1994
GS
161 perlapi Perl API listing (autogenerated)
162 perlintern Perl internal functions (autogenerated)
dc5c060f 163 perliol C API for Perl's implementation of IO in Layers
4755096e 164 perlapio Perl internal IO abstraction interface
fd7b6849 165
e8cd7eae 166 perlhack Perl hackers guide
04c692a8 167 perlsource Guide to the Perl source tree
1c2e8cca 168 perlinterp Overview of the Perl interpreter source and how it works
04c692a8
DR
169 perlhacktut Walk through the creation of a simple C code patch
170 perlhacktips Tips for Perl core C code hacking
cb8a010e 171 perlpolicy Perl development policies
04c692a8 172 perlgit Using git with the Perl repository
4755096e 173
fd7b6849
MJD
174=head2 Miscellaneous
175
176 perlbook Perl book information
cbd87e7e 177 perlcommunity Perl community information
fd7b6849 178
2a551100
JH
179 perldoc Look up Perl documentation in Pod format
180
fb9cefb4 181 perlhist Perl history records
bdfb6cc8 182 perldelta Perl changes since previous version
3ce6a296 183 perl5258delta Perl changes in version 5.25.8
733dba2b 184 perl5257delta Perl changes in version 5.25.7
a09f502b 185 perl5256delta Perl changes in version 5.25.6
262514fd 186 perl5255delta Perl changes in version 5.25.5
be293293 187 perl5254delta Perl changes in version 5.25.4
c0ea3294 188 perl5253delta Perl changes in version 5.25.3
228bfab9 189 perl5252delta Perl changes in version 5.25.2
efdbe372 190 perl5251delta Perl changes in version 5.25.1
0302547a 191 perl5250delta Perl changes in version 5.25.0
4b8803f0 192 perl5240delta Perl changes in version 5.24.0
2f7cab8b 193 perl5222delta Perl changes in version 5.22.2
fd5868f3 194 perl5221delta Perl changes in version 5.22.1
2cfe9b50 195 perl5220delta Perl changes in version 5.22.0
9fd420ca 196 perl5203delta Perl changes in version 5.20.3
2b85b119 197 perl5202delta Perl changes in version 5.20.2
0c54b9fe 198 perl5201delta Perl changes in version 5.20.1
d1148309 199 perl5200delta Perl changes in version 5.20.0
e990b849 200 perl5184delta Perl changes in version 5.18.4
7b97958f 201 perl5182delta Perl changes in version 5.18.2
f4e35152 202 perl5181delta Perl changes in version 5.18.1
f13a3008 203 perl5180delta Perl changes in version 5.18.0
eaf7bcbf 204 perl5163delta Perl changes in version 5.16.3
d1148309
AP
205 perl5162delta Perl changes in version 5.16.2
206 perl5161delta Perl changes in version 5.16.1
05c8f9ed 207 perl5160delta Perl changes in version 5.16.0
1e5cc764 208 perl5144delta Perl changes in version 5.14.4
70ce046e 209 perl5143delta Perl changes in version 5.14.3
77efd0f7 210 perl5142delta Perl changes in version 5.14.2
10288c7a 211 perl5141delta Perl changes in version 5.14.1
066dc4d9 212 perl5140delta Perl changes in version 5.14.0
a5caed3e 213 perl5125delta Perl changes in version 5.12.5
0b67f426 214 perl5124delta Perl changes in version 5.12.4
6c5f5efa 215 perl5123delta Perl changes in version 5.12.3
e71d1a7d 216 perl5122delta Perl changes in version 5.12.2
bdfb6cc8 217 perl5121delta Perl changes in version 5.12.1
20d57231 218 perl5120delta Perl changes in version 5.12.0
7cdf958d 219 perl5101delta Perl changes in version 5.10.1
7120b314 220 perl5100delta Perl changes in version 5.10.0
fc5be808 221 perl589delta Perl changes in version 5.8.9
c11a53c6 222 perl588delta Perl changes in version 5.8.8
315ba985 223 perl587delta Perl changes in version 5.8.7
e4bb216d 224 perl586delta Perl changes in version 5.8.6
07e9b5fe 225 perl585delta Perl changes in version 5.8.5
5f15c94e 226 perl584delta Perl changes in version 5.8.4
2e038148
NC
227 perl583delta Perl changes in version 5.8.3
228 perl582delta Perl changes in version 5.8.2
b6235c4f 229 perl581delta Perl changes in version 5.8.1
2e038148 230 perl58delta Perl changes in version 5.8.0
493a87da 231 perl561delta Perl changes in version 5.6.1
41630250 232 perl56delta Perl changes in version 5.6
4755096e
GS
233 perl5005delta Perl changes in version 5.005
234 perl5004delta Perl changes in version 5.004
d516a115 235
42e73e1c 236 perlexperiment A listing of experimental features in Perl
237
2a551100
JH
238 perlartistic Perl Artistic License
239 perlgpl GNU General Public License
240
d8416318
JH
241=head2 Language-Specific
242
0aef0fe5
NC
243=for buildtoc flag +r
244
d8416318
JH
245 perlcn Perl for Simplified Chinese (in EUC-CN)
246 perljp Perl for Japanese (in EUC-JP)
247 perlko Perl for Korean (in EUC-KR)
248 perltw Perl for Traditional Chinese (in Big5)
249
fd7b6849
MJD
250=head2 Platform-Specific
251
37d4d706 252 perlaix Perl notes for AIX
a83b6f46 253 perlamiga Perl notes for AmigaOS
6001596e 254 perlandroid Perl notes for Android
dc5c060f 255 perlbs2000 Perl notes for POSIX-BC BS2000
a1f19229 256 perlce Perl notes for WinCE
49877630
GS
257 perlcygwin Perl notes for Cygwin
258 perldos Perl notes for DOS
41630250 259 perlfreebsd Perl notes for FreeBSD
f6706af3 260 perlhaiku Perl notes for Haiku
49877630 261 perlhpux Perl notes for HP-UX
a83b6f46 262 perlhurd Perl notes for Hurd
469e7be4 263 perlirix Perl notes for Irix
991e8403 264 perllinux Perl notes for Linux
26d9b02f 265 perlmacos Perl notes for Mac OS (Classic)
0d53b15f 266 perlmacosx Perl notes for Mac OS X
41630250 267 perlnetware Perl notes for NetWare
b0846812 268 perlopenbsd Perl notes for OpenBSD
49877630
GS
269 perlos2 Perl notes for OS/2
270 perlos390 Perl notes for OS/390
522b859a 271 perlos400 Perl notes for OS/400
a83b6f46
JH
272 perlplan9 Perl notes for Plan 9
273 perlqnx Perl notes for QNX
2f08ed66 274 perlriscos Perl notes for RISC OS
d420ca49 275 perlsolaris Perl notes for Solaris
27da23d5 276 perlsymbian Perl notes for Symbian
58534900 277 perlsynology Perl notes for Synology
772ff3b9 278 perltru64 Perl notes for Tru64
49877630 279 perlvms Perl notes for VMS
9a997319 280 perlvos Perl notes for Stratus VOS
49877630
GS
281 perlwin32 Perl notes for Windows
282
0aef0fe5
NC
283=for buildtoc flag -r
284
e653ab25
DR
285=head2 Stubs for Deleted Documents
286
287 perlboot
288 perlbot
9ab63835 289 perlrepository
5d0b49e8 290 perltodo
e653ab25
DR
291 perltooc
292 perltoot
293
0aef0fe5 294=for buildtoc __END__
35dec5db 295
6b43eec4
DG
296On a Unix-like system, these documentation files will usually also be
297available as manpages for use with the F<man> program.
a0d0e21e 298
f747cd2a
MB
299Some documentation is not available as man pages, so if a
300cross-reference is not found by man, try it with L<perldoc>. Perldoc can
301also take you directly to documentation for functions (with the B<-f>
302switch). See C<perldoc --help> (or C<perldoc perldoc> or C<man perldoc>)
303for other helpful options L<perldoc> has to offer.
304
6b43eec4 305In general, if something strange has gone wrong with your program and you're
71b5b092
SF
306not sure where you should look for help, try making your code comply with
307B<use strict> and B<use warnings>. These will often point out exactly
308where the trouble is.
a0d0e21e
LW
309
310=head1 DESCRIPTION
311
d27f2b2f
DG
312Perl officially stands for Practical Extraction and Report Language,
313except when it doesn't.
314
72033c14 315Perl was originally a language optimized for scanning arbitrary
a0d0e21e 316text files, extracting information from those text files, and printing
72033c14
JV
317reports based on that information. It quickly became a good language
318for many system management tasks. Over the years, Perl has grown into
b6538e4f 319a general-purpose programming language. It's widely used for everything
72033c14
JV
320from quick "one-liners" to full-scale application development.
321
322The language is intended to be practical (easy to use, efficient,
c1264fa8
RS
323complete) rather than beautiful (tiny, elegant, minimal). It combines
324(in the author's opinion, anyway) some of the best features of B<sed>,
0e7bd06d 325B<awk>, and B<sh>, making it familiar and easy to use for Unix users to
c1264fa8
RS
326whip up quick solutions to annoying problems. Its general-purpose
327programming facilities support procedural, functional, and
328object-oriented programming paradigms, making Perl a comfortable
329language for the long haul on major projects, whatever your bent.
330
331Perl's roots in text processing haven't been forgotten over the years.
332It still boasts some of the most powerful regular expressions to be
333found anywhere, and its support for Unicode text is world-class. It
334handles all kinds of structured text, too, through an extensive
335collection of extensions. Those libraries, collected in the CPAN,
336provide ready-made solutions to an astounding array of problems. When
337they haven't set the standard themselves, they steal from the best
338-- just like Perl itself.
a0d0e21e 339
8e465e4e
JH
340=head1 AVAILABILITY
341
14218588 342Perl is available for most operating systems, including virtually
055fd3a9
GS
343all Unix-like platforms. See L<perlport/"Supported Platforms">
344for a listing.
8bc4a6bb 345
a0d0e21e
LW
346=head1 ENVIRONMENT
347
1e422769 348See L<perlrun>.
a0d0e21e
LW
349
350=head1 AUTHOR
351
19799a22 352Larry Wall <larry@wall.org>, with the help of oodles of other folks.
a0d0e21e 353
a99b1639
TP
354If your Perl success stories and testimonials may be of help to others
355who wish to advocate the use of Perl in their applications,
356or if you wish to simply express your gratitude to Larry and the
19799a22 357Perl developers, please write to perl-thanks@perl.org .
a99b1639 358
a0d0e21e
LW
359=head1 FILES
360
5f05dabc 361 "@INC" locations of perl libraries
a0d0e21e 362
5290b67b
DH
363"@INC" above is a reference to the built-in variable of the same name;
364see L<perlvar> for more information.
365
a0d0e21e
LW
366=head1 SEE ALSO
367
c5f69108 368 http://www.perl.org/ the Perl homepage
da9e6348 369 http://www.perl.com/ Perl articles (O'Reilly)
f6b3c421 370 http://www.cpan.org/ the Comprehensive Perl Archive
c5f69108 371 http://www.pm.org/ the Perl Mongers
19799a22 372
a0d0e21e
LW
373=head1 DIAGNOSTICS
374
71b5b092
SF
375Using the C<use strict> pragma ensures that all variables are properly
376declared and prevents other misuses of legacy Perl features.
377
6753a9e9
SF
378The C<use warnings> pragma produces some lovely diagnostics. One can
379also use the B<-w> flag, but its use is normally discouraged, because
380it gets applied to all executed Perl code, including that not under
381your control.
a0d0e21e 382
5a964f20
TC
383See L<perldiag> for explanations of all Perl's diagnostics. The C<use
384diagnostics> pragma automatically turns Perl's normally terse warnings
385and errors into these longer forms.
a0d0e21e
LW
386
387Compilation errors will tell you the line number of the error, with an
388indication of the next token or token type that was to be examined.
14218588 389(In a script passed to Perl via B<-e> switches, each
a0d0e21e
LW
390B<-e> is counted as one line.)
391
392Setuid scripts have additional constraints that can produce error
393messages such as "Insecure dependency". See L<perlsec>.
394
71b5b092
SF
395Did we mention that you should definitely consider using the B<use warnings>
396pragma?
a0d0e21e
LW
397
398=head1 BUGS
399
71b5b092 400The behavior implied by the B<use warnings> pragma is not mandatory.
a0d0e21e
LW
401
402Perl is at the mercy of your machine's definitions of various
1b3f7d21
CS
403operations such as type casting, atof(), and floating-point
404output with sprintf().
a0d0e21e 405
748a9306 406If your stdio requires a seek or eof between reads and writes on a
a0d0e21e
LW
407particular stream, so does Perl. (This doesn't apply to sysread()
408and syswrite().)
409
410While none of the built-in data types have any arbitrary size limits
411(apart from memory size), there are still a few arbitrary limits: a
a30ac152
GS
412given variable name may not be longer than 251 characters. Line numbers
413displayed by diagnostics are internally stored as short integers,
414so they are limited to a maximum of 65535 (higher numbers usually being
415affected by wraparound).
a0d0e21e 416
b0607b7a 417You may mail your bug reports (be sure to include full configuration
19799a22 418information as output by the myconfig program in the perl source
7f2de2d2 419tree, or by C<perl -V>) to perlbug@perl.org . If you've succeeded
7f89f796 420in compiling perl, the L<perlbug> script in the F<utils/> subdirectory
19799a22 421can be used to help mail in a bug report.
4633a7c4 422
a0d0e21e
LW
423Perl actually stands for Pathologically Eclectic Rubbish Lister, but
424don't tell anyone I said that.
425
426=head1 NOTES
427
428The Perl motto is "There's more than one way to do it." Divining
429how many more is left as an exercise to the reader.
430
4633a7c4 431The three principal virtues of a programmer are Laziness,
a0d0e21e 432Impatience, and Hubris. See the Camel Book for why.
16d20bd9 433