This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
Merge branch 'leont/xs_dynaloader' into blead
[perl5.git] / pod / perl.pod
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1=head1 NAME
2
095a5c3e 3perl - The Perl 5 language interpreter
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4
5=head1 SYNOPSIS
6
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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>] >]>
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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
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18For more information on these options, you can run C<perldoc perlrun>.
19
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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
71c89d21 24online at L<https://www.perl.org/>.
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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>.
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30
31For ease of access, the Perl manual has been split up into several sections.
a0d0e21e 32
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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
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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
2560602c 47aux h2ph h2xs perlbug pl2pm pod2html pod2man splain xsubpp
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48
49=end buildtoc
50
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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
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58=head2 Tutorials
59
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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
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65 perlretut Perl regular expressions tutorial
66
82e1c0d9 67 perlootut Perl OO tutorial for beginners
7a2320f0 68
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69 perlperf Perl Performance and Optimization Techniques
70
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71 perlstyle Perl style guide
72
41630250 73 perlcheat Perl cheat sheet
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74 perltrap Perl traps for the unwary
75 perldebtut Perl debugging tutorial
76
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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
4fb67a97 99 perldocstyle Perl style guide for core docs
f4d47668 100 perlpodstyle Perl POD style guide
c2e66d9e 101 perldiag Perl diagnostic messages
9021a1cf 102 perldeprecation Perl deprecations
41630250 103 perllexwarn Perl warnings and their control
4755096e 104 perldebug Perl debugging
fb9cefb4 105 perlvar Perl predefined variables
4755096e 106 perlre Perl regular expressions, the rest of the story
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107 perlrebackslash Perl regular expression backslash sequences
108 perlrecharclass Perl regular expression character classes
30487ceb 109 perlreref Perl regular expressions quick reference
d396a558 110 perlref Perl references, the rest of the story
fb9cefb4 111 perlform Perl formats
d396a558 112 perlobj Perl objects
d396a558 113 perltie Perl objects hidden behind simple variables
fd7b6849 114 perldbmfilter Perl DBM filters
760ac839 115
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116 perlipc Perl interprocess communication
117 perlfork Perl fork() information
118 perlnumber Perl number semantics
53d7eaa8 119
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120 perlthrtut Perl threads tutorial
121
122 perlport Perl portability guide
d396a558 123 perllocale Perl locale support
07fcf8ff 124 perluniintro Perl Unicode introduction
41630250 125 perlunicode Perl Unicode support
5dd47fd4 126 perlunicook Perl Unicode cookbook
3426ea3d 127 perlunifaq Perl Unicode FAQ
0cb5a9a8 128 perluniprops Index of Unicode properties in Perl
aadaa455 129 perlunitut Perl Unicode tutorial
d396a558 130 perlebcdic Considerations for running Perl on EBCDIC platforms
c2e66d9e 131
d396a558 132 perlsec Perl security
b135fd4a 133 perlsecpolicy Perl security report handling policy
4755096e 134
c2e66d9e 135 perlmod Perl modules: how they work
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136 perlmodlib Perl modules: how to write and use
137 perlmodstyle Perl modules: how to write modules with style
fd7b6849 138 perlmodinstall Perl modules: how to install from CPAN
c2e66d9e 139 perlnewmod Perl modules: preparing a new module for distribution
a550ee30 140 perlpragma Perl modules: writing a user pragma
760ac839 141
fd7b6849 142 perlutil utilities packaged with the Perl distribution
760ac839 143
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144 perlfilter Perl source filters
145
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146 perldtrace Perl's support for DTrace
147
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148 perlglossary Perl Glossary
149
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150=head2 Internals and C Language Interface
151
fb9cefb4 152 perlembed Perl ways to embed perl in your C or C++ application
41630250 153 perldebguts Perl debugging guts and tips
fb9cefb4 154 perlxstut Perl XS tutorial
4755096e 155 perlxs Perl XS application programming interface
0eb29def 156 perlxstypemap Perl XS C/Perl type conversion tools
f40a6c71 157 perlclib Internal replacements for standard C library functions
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158 perlguts Perl internal functions for those doing extensions
159 perlcall Perl calling conventions from C
15932acc 160 perlmroapi Perl method resolution plugin interface
108003db 161 perlreapi Perl regular expression plugin interface
b23a565d 162 perlreguts Perl regular expression engine internals
fd7b6849 163
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164 perlapi Perl API listing (autogenerated)
165 perlintern Perl internal functions (autogenerated)
dc5c060f 166 perliol C API for Perl's implementation of IO in Layers
4755096e 167 perlapio Perl internal IO abstraction interface
fd7b6849 168
e8cd7eae 169 perlhack Perl hackers guide
04c692a8 170 perlsource Guide to the Perl source tree
1c2e8cca 171 perlinterp Overview of the Perl interpreter source and how it works
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172 perlhacktut Walk through the creation of a simple C code patch
173 perlhacktips Tips for Perl core C code hacking
cb8a010e 174 perlpolicy Perl development policies
f8e911a1 175 perlgov Perl Rules of Governance
04c692a8 176 perlgit Using git with the Perl repository
4755096e 177
d1690fb1 178=head2 History
2a551100 179
fb9cefb4 180 perlhist Perl history records
bdfb6cc8 181 perldelta Perl changes since previous version
b7d6a4ec 182 perl5351delta Perl changes in version 5.35.1
9623941f 183 perl5350delta Perl changes in version 5.35.0
b129a266 184 perl5340delta Perl changes in version 5.34.0
1d0cdb1d 185 perl5321delta Perl changes in version 5.32.1
0382c61d 186 perl5320delta Perl changes in version 5.32.0
189c2812 187 perl5303delta Perl changes in version 5.30.3
fb01b0b0 188 perl5302delta Perl changes in version 5.30.2
9f26aead 189 perl5301delta Perl changes in version 5.30.1
5560f8d2 190 perl5300delta Perl changes in version 5.30.0
189c2812 191 perl5283delta Perl changes in version 5.28.3
bea9954d 192 perl5282delta Perl changes in version 5.28.2
43323ad1 193 perl5281delta Perl changes in version 5.28.1
b0394755 194 perl5280delta Perl changes in version 5.28.0
43323ad1 195 perl5263delta Perl changes in version 5.26.3
fb51aa58 196 perl5262delta Perl changes in version 5.26.2
c592f515 197 perl5261delta Perl changes in version 5.26.1
b5cbfe35 198 perl5260delta Perl changes in version 5.26.0
fb51aa58 199 perl5244delta Perl changes in version 5.24.4
c592f515 200 perl5243delta Perl changes in version 5.24.3
50d330d7 201 perl5242delta Perl changes in version 5.24.2
f4a48a9e 202 perl5241delta Perl changes in version 5.24.1
4b8803f0 203 perl5240delta Perl changes in version 5.24.0
50d330d7 204 perl5224delta Perl changes in version 5.22.4
f4a48a9e 205 perl5223delta Perl changes in version 5.22.3
2f7cab8b 206 perl5222delta Perl changes in version 5.22.2
fd5868f3 207 perl5221delta Perl changes in version 5.22.1
2cfe9b50 208 perl5220delta Perl changes in version 5.22.0
9fd420ca 209 perl5203delta Perl changes in version 5.20.3
2b85b119 210 perl5202delta Perl changes in version 5.20.2
0c54b9fe 211 perl5201delta Perl changes in version 5.20.1
d1148309 212 perl5200delta Perl changes in version 5.20.0
e990b849 213 perl5184delta Perl changes in version 5.18.4
7b97958f 214 perl5182delta Perl changes in version 5.18.2
f4e35152 215 perl5181delta Perl changes in version 5.18.1
f13a3008 216 perl5180delta Perl changes in version 5.18.0
eaf7bcbf 217 perl5163delta Perl changes in version 5.16.3
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218 perl5162delta Perl changes in version 5.16.2
219 perl5161delta Perl changes in version 5.16.1
05c8f9ed 220 perl5160delta Perl changes in version 5.16.0
1e5cc764 221 perl5144delta Perl changes in version 5.14.4
70ce046e 222 perl5143delta Perl changes in version 5.14.3
77efd0f7 223 perl5142delta Perl changes in version 5.14.2
10288c7a 224 perl5141delta Perl changes in version 5.14.1
066dc4d9 225 perl5140delta Perl changes in version 5.14.0
a5caed3e 226 perl5125delta Perl changes in version 5.12.5
0b67f426 227 perl5124delta Perl changes in version 5.12.4
6c5f5efa 228 perl5123delta Perl changes in version 5.12.3
e71d1a7d 229 perl5122delta Perl changes in version 5.12.2
bdfb6cc8 230 perl5121delta Perl changes in version 5.12.1
20d57231 231 perl5120delta Perl changes in version 5.12.0
7cdf958d 232 perl5101delta Perl changes in version 5.10.1
7120b314 233 perl5100delta Perl changes in version 5.10.0
fc5be808 234 perl589delta Perl changes in version 5.8.9
c11a53c6 235 perl588delta Perl changes in version 5.8.8
315ba985 236 perl587delta Perl changes in version 5.8.7
e4bb216d 237 perl586delta Perl changes in version 5.8.6
07e9b5fe 238 perl585delta Perl changes in version 5.8.5
5f15c94e 239 perl584delta Perl changes in version 5.8.4
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240 perl583delta Perl changes in version 5.8.3
241 perl582delta Perl changes in version 5.8.2
b6235c4f 242 perl581delta Perl changes in version 5.8.1
2e038148 243 perl58delta Perl changes in version 5.8.0
493a87da 244 perl561delta Perl changes in version 5.6.1
41630250 245 perl56delta Perl changes in version 5.6
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246 perl5005delta Perl changes in version 5.005
247 perl5004delta Perl changes in version 5.004
d516a115 248
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249=head2 Miscellaneous
250
251 perlbook Perl book information
252 perlcommunity Perl community information
253
254 perldoc Look up Perl documentation in Pod format
255
42e73e1c 256 perlexperiment A listing of experimental features in Perl
257
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258 perlartistic Perl Artistic License
259 perlgpl GNU General Public License
260
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261=head2 Language-Specific
262
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263=for buildtoc flag +r
264
fadae0ba 265 perlcn Perl for Simplified Chinese (in UTF-8)
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266 perljp Perl for Japanese (in EUC-JP)
267 perlko Perl for Korean (in EUC-KR)
268 perltw Perl for Traditional Chinese (in Big5)
269
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270=head2 Platform-Specific
271
37d4d706 272 perlaix Perl notes for AIX
a83b6f46 273 perlamiga Perl notes for AmigaOS
6001596e 274 perlandroid Perl notes for Android
dc5c060f 275 perlbs2000 Perl notes for POSIX-BC BS2000
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276 perlcygwin Perl notes for Cygwin
277 perldos Perl notes for DOS
41630250 278 perlfreebsd Perl notes for FreeBSD
f6706af3 279 perlhaiku Perl notes for Haiku
49877630 280 perlhpux Perl notes for HP-UX
a83b6f46 281 perlhurd Perl notes for Hurd
469e7be4 282 perlirix Perl notes for Irix
991e8403 283 perllinux Perl notes for Linux
26d9b02f 284 perlmacos Perl notes for Mac OS (Classic)
0d53b15f 285 perlmacosx Perl notes for Mac OS X
41630250 286 perlnetware Perl notes for NetWare
b0846812 287 perlopenbsd Perl notes for OpenBSD
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288 perlos2 Perl notes for OS/2
289 perlos390 Perl notes for OS/390
522b859a 290 perlos400 Perl notes for OS/400
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291 perlplan9 Perl notes for Plan 9
292 perlqnx Perl notes for QNX
2f08ed66 293 perlriscos Perl notes for RISC OS
d420ca49 294 perlsolaris Perl notes for Solaris
58534900 295 perlsynology Perl notes for Synology
772ff3b9 296 perltru64 Perl notes for Tru64
49877630 297 perlvms Perl notes for VMS
9a997319 298 perlvos Perl notes for Stratus VOS
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299 perlwin32 Perl notes for Windows
300
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301=for buildtoc flag -r
302
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303=head2 Stubs for Deleted Documents
304
305 perlboot
306 perlbot
9ab63835 307 perlrepository
5d0b49e8 308 perltodo
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309 perltooc
310 perltoot
311
0aef0fe5 312=for buildtoc __END__
35dec5db 313
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314On a Unix-like system, these documentation files will usually also be
315available as manpages for use with the F<man> program.
a0d0e21e 316
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317Some documentation is not available as man pages, so if a
318cross-reference is not found by man, try it with L<perldoc>. Perldoc can
319also take you directly to documentation for functions (with the B<-f>
320switch). See C<perldoc --help> (or C<perldoc perldoc> or C<man perldoc>)
321for other helpful options L<perldoc> has to offer.
322
6b43eec4 323In general, if something strange has gone wrong with your program and you're
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324not sure where you should look for help, try making your code comply with
325B<use strict> and B<use warnings>. These will often point out exactly
326where the trouble is.
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327
328=head1 DESCRIPTION
329
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330Perl officially stands for Practical Extraction and Report Language,
331except when it doesn't.
332
72033c14 333Perl was originally a language optimized for scanning arbitrary
a0d0e21e 334text files, extracting information from those text files, and printing
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335reports based on that information. It quickly became a good language
336for many system management tasks. Over the years, Perl has grown into
b6538e4f 337a general-purpose programming language. It's widely used for everything
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338from quick "one-liners" to full-scale application development.
339
340The language is intended to be practical (easy to use, efficient,
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341complete) rather than beautiful (tiny, elegant, minimal). It combines
342(in the author's opinion, anyway) some of the best features of B<sed>,
0e7bd06d 343B<awk>, and B<sh>, making it familiar and easy to use for Unix users to
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344whip up quick solutions to annoying problems. Its general-purpose
345programming facilities support procedural, functional, and
346object-oriented programming paradigms, making Perl a comfortable
347language for the long haul on major projects, whatever your bent.
348
349Perl's roots in text processing haven't been forgotten over the years.
350It still boasts some of the most powerful regular expressions to be
351found anywhere, and its support for Unicode text is world-class. It
352handles all kinds of structured text, too, through an extensive
353collection of extensions. Those libraries, collected in the CPAN,
354provide ready-made solutions to an astounding array of problems. When
355they haven't set the standard themselves, they steal from the best
356-- just like Perl itself.
a0d0e21e 357
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358=head1 AVAILABILITY
359
14218588 360Perl is available for most operating systems, including virtually
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361all Unix-like platforms. See L<perlport/"Supported Platforms">
362for a listing.
8bc4a6bb 363
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364=head1 ENVIRONMENT
365
028611fa 366See L<perlrun/ENVIRONMENT>.
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367
368=head1 AUTHOR
369
19799a22 370Larry Wall <larry@wall.org>, with the help of oodles of other folks.
a0d0e21e 371
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372If your Perl success stories and testimonials may be of help to others
373who wish to advocate the use of Perl in their applications,
374or if you wish to simply express your gratitude to Larry and the
19799a22 375Perl developers, please write to perl-thanks@perl.org .
a99b1639 376
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377=head1 FILES
378
5f05dabc 379 "@INC" locations of perl libraries
a0d0e21e 380
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381"@INC" above is a reference to the built-in variable of the same name;
382see L<perlvar> for more information.
383
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384=head1 SEE ALSO
385
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386 https://www.perl.org/ the Perl homepage
387 https://www.perl.com/ Perl articles
388 https://www.cpan.org/ the Comprehensive Perl Archive
389 https://www.pm.org/ the Perl Mongers
19799a22 390
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391=head1 DIAGNOSTICS
392
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393Using the C<use strict> pragma ensures that all variables are properly
394declared and prevents other misuses of legacy Perl features.
395
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396The C<use warnings> pragma produces some lovely diagnostics. One can
397also use the B<-w> flag, but its use is normally discouraged, because
398it gets applied to all executed Perl code, including that not under
399your control.
a0d0e21e 400
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401See L<perldiag> for explanations of all Perl's diagnostics. The C<use
402diagnostics> pragma automatically turns Perl's normally terse warnings
403and errors into these longer forms.
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404
405Compilation errors will tell you the line number of the error, with an
406indication of the next token or token type that was to be examined.
14218588 407(In a script passed to Perl via B<-e> switches, each
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408B<-e> is counted as one line.)
409
410Setuid scripts have additional constraints that can produce error
411messages such as "Insecure dependency". See L<perlsec>.
412
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413Did we mention that you should definitely consider using the B<use warnings>
414pragma?
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415
416=head1 BUGS
417
71b5b092 418The behavior implied by the B<use warnings> pragma is not mandatory.
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419
420Perl is at the mercy of your machine's definitions of various
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421operations such as type casting, atof(), and floating-point
422output with sprintf().
a0d0e21e 423
748a9306 424If your stdio requires a seek or eof between reads and writes on a
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425particular stream, so does Perl. (This doesn't apply to sysread()
426and syswrite().)
427
428While none of the built-in data types have any arbitrary size limits
429(apart from memory size), there are still a few arbitrary limits: a
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430given variable name may not be longer than 251 characters. Line numbers
431displayed by diagnostics are internally stored as short integers,
432so they are limited to a maximum of 65535 (higher numbers usually being
433affected by wraparound).
a0d0e21e 434
8166b4e0 435You may submit your bug reports (be sure to include full configuration
19799a22 436information as output by the myconfig program in the perl source
8166b4e0 437tree, or by C<perl -V>) to L<https://github.com/Perl/perl5/issues>.
4633a7c4 438
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439Perl actually stands for Pathologically Eclectic Rubbish Lister, but
440don't tell anyone I said that.
441
442=head1 NOTES
443
444The Perl motto is "There's more than one way to do it." Divining
445how many more is left as an exercise to the reader.
446
4633a7c4 447The three principal virtues of a programmer are Laziness,
a0d0e21e 448Impatience, and Hubris. See the Camel Book for why.
16d20bd9 449