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1=head1 NAME
2
d27f2b2f 3perl - The Perl 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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18=head1 GETTING HELP
19
20The F<perldoc> program gives you access to all the documentation that comes
21with Perl. You can get more documentation, tutorials and community support
22online at L<http://www.perl.org/>.
23
24If you're new to Perl, you should start by running C<perldoc perlintro>,
25which is a general intro for beginners and provides some background to help
26you navigate the rest of Perl's extensive documentation. Run C<perldoc
27perldoc> to learn more things you can do with F<perldoc>.
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28
29For ease of access, the Perl manual has been split up into several sections.
a0d0e21e 30
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31=head2 Overview
32
fb9cefb4 33 perl Perl overview (this section)
10151d09 34 perlintro Perl introduction for beginners
fb9cefb4 35 perltoc Perl documentation table of contents
760ac839 36
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37=head2 Tutorials
38
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39 perlreftut Perl references short introduction
40 perldsc Perl data structures intro
41 perllol Perl data structures: arrays of arrays
7a2320f0 42
41630250 43 perlrequick Perl regular expressions quick start
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44 perlretut Perl regular expressions tutorial
45
46 perlboot Perl OO tutorial for beginners
47 perltoot Perl OO tutorial, part 1
48 perltooc Perl OO tutorial, part 2
49 perlbot Perl OO tricks and examples
50
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51 perlperf Perl Performance and Optimization Techniques
52
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53 perlstyle Perl style guide
54
41630250 55 perlcheat Perl cheat sheet
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56 perltrap Perl traps for the unwary
57 perldebtut Perl debugging tutorial
58
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59 perlfaq Perl frequently asked questions
60 perlfaq1 General Questions About Perl
61 perlfaq2 Obtaining and Learning about Perl
62 perlfaq3 Programming Tools
63 perlfaq4 Data Manipulation
64 perlfaq5 Files and Formats
65 perlfaq6 Regexes
66 perlfaq7 Perl Language Issues
67 perlfaq8 System Interaction
68 perlfaq9 Networking
0f542199 69
fd7b6849 70=head2 Reference Manual
413510b3 71
fb9cefb4 72 perlsyn Perl syntax
4755096e 73 perldata Perl data structures
fb9cefb4 74 perlop Perl operators and precedence
c2e66d9e 75 perlsub Perl subroutines
fd7b6849 76 perlfunc Perl built-in functions
413510b3 77 perlopentut Perl open() tutorial
41630250 78 perlpacktut Perl pack() and unpack() tutorial
c2e66d9e 79 perlpod Perl plain old documentation
41630250 80 perlpodspec Perl plain old documentation format specification
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81 perlrun Perl execution and options
82 perldiag Perl diagnostic messages
41630250 83 perllexwarn Perl warnings and their control
4755096e 84 perldebug Perl debugging
fb9cefb4 85 perlvar Perl predefined variables
4755096e 86 perlre Perl regular expressions, the rest of the story
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87 perlrebackslash Perl regular expression backslash sequences
88 perlrecharclass Perl regular expression character classes
30487ceb 89 perlreref Perl regular expressions quick reference
d396a558 90 perlref Perl references, the rest of the story
fb9cefb4 91 perlform Perl formats
d396a558 92 perlobj Perl objects
d396a558 93 perltie Perl objects hidden behind simple variables
fd7b6849 94 perldbmfilter Perl DBM filters
760ac839 95
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96 perlipc Perl interprocess communication
97 perlfork Perl fork() information
98 perlnumber Perl number semantics
53d7eaa8 99
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100 perlthrtut Perl threads tutorial
101
102 perlport Perl portability guide
d396a558 103 perllocale Perl locale support
07fcf8ff 104 perluniintro Perl Unicode introduction
41630250 105 perlunicode Perl Unicode support
3426ea3d 106 perlunifaq Perl Unicode FAQ
7cf8de9f 107 perluniprops Index of Unicode Version 5.2.0 properties in Perl
aadaa455 108 perlunitut Perl Unicode tutorial
d396a558 109 perlebcdic Considerations for running Perl on EBCDIC platforms
c2e66d9e 110
d396a558 111 perlsec Perl security
4755096e 112
c2e66d9e 113 perlmod Perl modules: how they work
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114 perlmodlib Perl modules: how to write and use
115 perlmodstyle Perl modules: how to write modules with style
fd7b6849 116 perlmodinstall Perl modules: how to install from CPAN
c2e66d9e 117 perlnewmod Perl modules: preparing a new module for distribution
a550ee30 118 perlpragma Perl modules: writing a user pragma
760ac839 119
fd7b6849 120 perlutil utilities packaged with the Perl distribution
760ac839 121
41630250 122 perlcompile Perl compiler suite intro
760ac839 123
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124 perlfilter Perl source filters
125
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126 perlglossary Perl Glossary
127
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128=head2 Internals and C Language Interface
129
fb9cefb4 130 perlembed Perl ways to embed perl in your C or C++ application
41630250 131 perldebguts Perl debugging guts and tips
fb9cefb4 132 perlxstut Perl XS tutorial
4755096e 133 perlxs Perl XS application programming interface
f40a6c71 134 perlclib Internal replacements for standard C library functions
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135 perlguts Perl internal functions for those doing extensions
136 perlcall Perl calling conventions from C
15932acc 137 perlmroapi Perl method resolution plugin interface
108003db 138 perlreapi Perl regular expression plugin interface
b23a565d 139 perlreguts Perl regular expression engine internals
fd7b6849 140
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141 perlapi Perl API listing (autogenerated)
142 perlintern Perl internal functions (autogenerated)
dc5c060f 143 perliol C API for Perl's implementation of IO in Layers
4755096e 144 perlapio Perl internal IO abstraction interface
fd7b6849 145
e8cd7eae 146 perlhack Perl hackers guide
cb8a010e 147 perlpolicy Perl development policies
00f54a07 148 perlrepository Perl source repository
4755096e 149
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150=head2 Miscellaneous
151
152 perlbook Perl book information
cbd87e7e 153 perlcommunity Perl community information
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154 perltodo Perl things to do
155
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156 perldoc Look up Perl documentation in Pod format
157
fb9cefb4 158 perlhist Perl history records
bdfb6cc8 159 perldelta Perl changes since previous version
855e1b21 160 perl5132delta Perl changes in version 5.13.2
f83c51e5 161 perl5131delta Perl changes in version 5.13.1
d4438f94 162 perl5130delta Perl changes in version 5.13.0
bdfb6cc8 163 perl5121delta Perl changes in version 5.12.1
20d57231 164 perl5120delta Perl changes in version 5.12.0
655da5cf 165 perl5115delta Perl changes in version 5.11.5
3be84f1f 166 perl5114delta Perl changes in version 5.11.4
e06a4ec4 167 perl5113delta Perl changes in version 5.11.3
2e8102e6 168 perl5112delta Perl changes in version 5.11.2
d5114285 169 perl5111delta Perl changes in version 5.11.1
11545435 170 perl5110delta Perl changes in version 5.11.0
7cdf958d 171 perl5101delta Perl changes in version 5.10.1
7120b314 172 perl5100delta Perl changes in version 5.10.0
cf6c151c 173 perl595delta Perl changes in version 5.9.5
f6eae373 174 perl594delta Perl changes in version 5.9.4
6c7deadb 175 perl593delta Perl changes in version 5.9.3
496c75d0 176 perl592delta Perl changes in version 5.9.2
e0eb806d 177 perl591delta Perl changes in version 5.9.1
1400179b 178 perl590delta Perl changes in version 5.9.0
fc5be808 179 perl589delta Perl changes in version 5.8.9
c11a53c6 180 perl588delta Perl changes in version 5.8.8
315ba985 181 perl587delta Perl changes in version 5.8.7
e4bb216d 182 perl586delta Perl changes in version 5.8.6
07e9b5fe 183 perl585delta Perl changes in version 5.8.5
5f15c94e 184 perl584delta Perl changes in version 5.8.4
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185 perl583delta Perl changes in version 5.8.3
186 perl582delta Perl changes in version 5.8.2
b6235c4f 187 perl581delta Perl changes in version 5.8.1
2e038148 188 perl58delta Perl changes in version 5.8.0
77b096b5 189 perl573delta Perl changes in version 5.7.3
245d750e 190 perl572delta Perl changes in version 5.7.2
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191 perl571delta Perl changes in version 5.7.1
192 perl570delta Perl changes in version 5.7.0
493a87da 193 perl561delta Perl changes in version 5.6.1
41630250 194 perl56delta Perl changes in version 5.6
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195 perl5005delta Perl changes in version 5.005
196 perl5004delta Perl changes in version 5.004
d516a115 197
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198 perlartistic Perl Artistic License
199 perlgpl GNU General Public License
200
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201=head2 Language-Specific
202
203 perlcn Perl for Simplified Chinese (in EUC-CN)
204 perljp Perl for Japanese (in EUC-JP)
205 perlko Perl for Korean (in EUC-KR)
206 perltw Perl for Traditional Chinese (in Big5)
207
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208=head2 Platform-Specific
209
37d4d706 210 perlaix Perl notes for AIX
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211 perlamiga Perl notes for AmigaOS
212 perlapollo Perl notes for Apollo DomainOS
213 perlbeos Perl notes for BeOS
dc5c060f 214 perlbs2000 Perl notes for POSIX-BC BS2000
a1f19229 215 perlce Perl notes for WinCE
49877630 216 perlcygwin Perl notes for Cygwin
245d750e 217 perldgux Perl notes for DG/UX
49877630 218 perldos Perl notes for DOS
9a997319 219 perlepoc Perl notes for EPOC
41630250 220 perlfreebsd Perl notes for FreeBSD
f6706af3 221 perlhaiku Perl notes for Haiku
49877630 222 perlhpux Perl notes for HP-UX
a83b6f46 223 perlhurd Perl notes for Hurd
469e7be4 224 perlirix Perl notes for Irix
991e8403 225 perllinux Perl notes for Linux
26d9b02f 226 perlmacos Perl notes for Mac OS (Classic)
0d53b15f 227 perlmacosx Perl notes for Mac OS X
ab648d5e 228 perlmpeix Perl notes for MPE/iX
41630250 229 perlnetware Perl notes for NetWare
b0846812 230 perlopenbsd Perl notes for OpenBSD
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231 perlos2 Perl notes for OS/2
232 perlos390 Perl notes for OS/390
522b859a 233 perlos400 Perl notes for OS/400
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234 perlplan9 Perl notes for Plan 9
235 perlqnx Perl notes for QNX
2f08ed66 236 perlriscos Perl notes for RISC OS
d420ca49 237 perlsolaris Perl notes for Solaris
27da23d5 238 perlsymbian Perl notes for Symbian
772ff3b9 239 perltru64 Perl notes for Tru64
41630250 240 perluts Perl notes for UTS
cbe1151c 241 perlvmesa Perl notes for VM/ESA
49877630 242 perlvms Perl notes for VMS
9a997319 243 perlvos Perl notes for Stratus VOS
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244 perlwin32 Perl notes for Windows
245
35dec5db 246
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247On a Unix-like system, these documentation files will usually also be
248available as manpages for use with the F<man> program.
a0d0e21e 249
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250In general, if something strange has gone wrong with your program and you're
251not sure where you should look for help, try the B<-w> switch first. It will
252often point out exactly where the trouble is.
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253
254=head1 DESCRIPTION
255
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256Perl officially stands for Practical Extraction and Report Language,
257except when it doesn't.
258
5f05dabc 259Perl is a language optimized for scanning arbitrary
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260text files, extracting information from those text files, and printing
261reports based on that information. It's also a good language for many
262system management tasks. The language is intended to be practical
263(easy to use, efficient, complete) rather than beautiful (tiny,
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264elegant, minimal).
265
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266Perl combines (in the author's opinion, anyway) some of the best
267features of C, B<sed>, B<awk>, and B<sh>, so people familiar with
268those languages should have little difficulty with it. (Language
269historians will also note some vestiges of B<csh>, Pascal, and even
14218588 270BASIC-PLUS.) Expression syntax corresponds closely to C
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271expression syntax. Unlike most Unix utilities, Perl does not
272arbitrarily limit the size of your data--if you've got the memory,
aa689395 273Perl can slurp in your whole file as a single string. Recursion is of
0f31cffe 274unlimited depth. And the tables used by hashes (sometimes called
aa689395 275"associative arrays") grow as necessary to prevent degraded
0f31cffe 276performance. Perl can use sophisticated pattern matching techniques to
14218588 277scan large amounts of data quickly. Although optimized for
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278scanning text, Perl can also deal with binary data, and can make dbm
279files look like hashes. Setuid Perl scripts are safer than C programs
14218588 280through a dataflow tracing mechanism that prevents many stupid
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281security holes.
282
283If you have a problem that would ordinarily use B<sed> or B<awk> or
284B<sh>, but it exceeds their capabilities or must run a little faster,
285and you don't want to write the silly thing in C, then Perl may be for
286you. There are also translators to turn your B<sed> and B<awk>
287scripts into Perl scripts.
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288
289But wait, there's more...
290
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291Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete
292rewrite that provides the following additional benefits:
a0d0e21e 293
13a2d996 294=over 4
a0d0e21e 295
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296=item *
297
298modularity and reusability using innumerable modules
a0d0e21e 299
19799a22 300Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>.
a0d0e21e 301
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302=item *
303
304embeddable and extensible
a0d0e21e 305
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306Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>,
307L<perlguts>, and L<xsubpp>.
a0d0e21e 308
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309=item *
310
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311roll-your-own magic variables (including multiple simultaneous DBM
312implementations)
a0d0e21e 313
19799a22 314Described in L<perltie> and L<AnyDBM_File>.
a0d0e21e 315
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316=item *
317
318subroutines can now be overridden, autoloaded, and prototyped
a0d0e21e 319
19799a22 320Described in L<perlsub>.
a0d0e21e 321
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322=item *
323
324arbitrarily nested data structures and anonymous functions
a0d0e21e 325
19799a22 326Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>.
a0d0e21e 327
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328=item *
329
330object-oriented programming
a0d0e21e 331
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332Described in L<perlobj>, L<perlboot>, L<perltoot>, L<perltooc>,
333and L<perlbot>.
a0d0e21e 334
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335=item *
336
551e1d92 337support for light-weight processes (threads)
a0d0e21e 338
63de3cb2 339Described in L<perlthrtut> and L<threads>.
a0d0e21e 340
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341=item *
342
63de3cb2 343support for Unicode, internationalization, and localization
a0d0e21e 344
63de3cb2 345Described in L<perluniintro>, L<perllocale> and L<Locale::Maketext>.
a0d0e21e 346
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347=item *
348
349lexical scoping
a0d0e21e 350
19799a22 351Described in L<perlsub>.
a0d0e21e 352
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353=item *
354
355regular expression enhancements
a0d0e21e 356
19799a22 357Described in L<perlre>, with additional examples in L<perlop>.
a0d0e21e 358
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359=item *
360
361enhanced debugger and interactive Perl environment,
362with integrated editor support
a0d0e21e 363
f6b3c421 364Described in L<perldebtut>, L<perldebug> and L<perldebguts>.
a0d0e21e 365
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366=item *
367
368POSIX 1003.1 compliant library
5f05dabc 369
19799a22 370Described in L<POSIX>.
5f05dabc 371
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372=back
373
68dc0745 374Okay, that's I<definitely> enough hype.
a0d0e21e 375
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376=head1 AVAILABILITY
377
14218588 378Perl is available for most operating systems, including virtually
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379all Unix-like platforms. See L<perlport/"Supported Platforms">
380for a listing.
8bc4a6bb 381
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382=head1 ENVIRONMENT
383
1e422769 384See L<perlrun>.
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385
386=head1 AUTHOR
387
19799a22 388Larry Wall <larry@wall.org>, with the help of oodles of other folks.
a0d0e21e 389
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390If your Perl success stories and testimonials may be of help to others
391who wish to advocate the use of Perl in their applications,
392or if you wish to simply express your gratitude to Larry and the
19799a22 393Perl developers, please write to perl-thanks@perl.org .
a99b1639 394
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395=head1 FILES
396
5f05dabc 397 "@INC" locations of perl libraries
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398
399=head1 SEE ALSO
400
401 a2p awk to perl translator
402 s2p sed to perl translator
403
c5f69108 404 http://www.perl.org/ the Perl homepage
da9e6348 405 http://www.perl.com/ Perl articles (O'Reilly)
f6b3c421 406 http://www.cpan.org/ the Comprehensive Perl Archive
c5f69108 407 http://www.pm.org/ the Perl Mongers
19799a22 408
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409=head1 DIAGNOSTICS
410
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411The C<use warnings> pragma (and the B<-w> switch) produces some
412lovely diagnostics.
a0d0e21e 413
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414See L<perldiag> for explanations of all Perl's diagnostics. The C<use
415diagnostics> pragma automatically turns Perl's normally terse warnings
416and errors into these longer forms.
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417
418Compilation errors will tell you the line number of the error, with an
419indication of the next token or token type that was to be examined.
14218588 420(In a script passed to Perl via B<-e> switches, each
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421B<-e> is counted as one line.)
422
423Setuid scripts have additional constraints that can produce error
424messages such as "Insecure dependency". See L<perlsec>.
425
426Did we mention that you should definitely consider using the B<-w>
427switch?
428
429=head1 BUGS
430
431The B<-w> switch is not mandatory.
432
433Perl is at the mercy of your machine's definitions of various
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434operations such as type casting, atof(), and floating-point
435output with sprintf().
a0d0e21e 436
748a9306 437If your stdio requires a seek or eof between reads and writes on a
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438particular stream, so does Perl. (This doesn't apply to sysread()
439and syswrite().)
440
441While none of the built-in data types have any arbitrary size limits
442(apart from memory size), there are still a few arbitrary limits: a
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443given variable name may not be longer than 251 characters. Line numbers
444displayed by diagnostics are internally stored as short integers,
445so they are limited to a maximum of 65535 (higher numbers usually being
446affected by wraparound).
a0d0e21e 447
b0607b7a 448You may mail your bug reports (be sure to include full configuration
19799a22 449information as output by the myconfig program in the perl source
7f2de2d2 450tree, or by C<perl -V>) to perlbug@perl.org . If you've succeeded
055fd3a9 451in compiling perl, the B<perlbug> script in the F<utils/> subdirectory
19799a22 452can be used to help mail in a bug report.
4633a7c4 453
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454Perl actually stands for Pathologically Eclectic Rubbish Lister, but
455don't tell anyone I said that.
456
457=head1 NOTES
458
459The Perl motto is "There's more than one way to do it." Divining
460how many more is left as an exercise to the reader.
461
4633a7c4 462The three principal virtues of a programmer are Laziness,
a0d0e21e 463Impatience, and Hubris. See the Camel Book for why.
16d20bd9 464