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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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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
82e1c0d9 46 perlootut Perl OO tutorial for beginners
7a2320f0 47
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48 perlperf Perl Performance and Optimization Techniques
49
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50 perlstyle Perl style guide
51
41630250 52 perlcheat Perl cheat sheet
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53 perltrap Perl traps for the unwary
54 perldebtut Perl debugging tutorial
55
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56 perlfaq Perl frequently asked questions
57 perlfaq1 General Questions About Perl
58 perlfaq2 Obtaining and Learning about Perl
59 perlfaq3 Programming Tools
60 perlfaq4 Data Manipulation
61 perlfaq5 Files and Formats
62 perlfaq6 Regexes
63 perlfaq7 Perl Language Issues
64 perlfaq8 System Interaction
65 perlfaq9 Networking
0f542199 66
fd7b6849 67=head2 Reference Manual
413510b3 68
fb9cefb4 69 perlsyn Perl syntax
4755096e 70 perldata Perl data structures
fb9cefb4 71 perlop Perl operators and precedence
c2e66d9e 72 perlsub Perl subroutines
fd7b6849 73 perlfunc Perl built-in functions
413510b3 74 perlopentut Perl open() tutorial
41630250 75 perlpacktut Perl pack() and unpack() tutorial
c2e66d9e 76 perlpod Perl plain old documentation
41630250 77 perlpodspec Perl plain old documentation format specification
f4d47668 78 perlpodstyle Perl POD style guide
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79 perlrun Perl execution and options
80 perldiag Perl diagnostic messages
41630250 81 perllexwarn Perl warnings and their control
4755096e 82 perldebug Perl debugging
fb9cefb4 83 perlvar Perl predefined variables
4755096e 84 perlre Perl regular expressions, the rest of the story
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85 perlrebackslash Perl regular expression backslash sequences
86 perlrecharclass Perl regular expression character classes
30487ceb 87 perlreref Perl regular expressions quick reference
d396a558 88 perlref Perl references, the rest of the story
fb9cefb4 89 perlform Perl formats
d396a558 90 perlobj Perl objects
d396a558 91 perltie Perl objects hidden behind simple variables
fd7b6849 92 perldbmfilter Perl DBM filters
760ac839 93
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94 perlipc Perl interprocess communication
95 perlfork Perl fork() information
96 perlnumber Perl number semantics
53d7eaa8 97
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98 perlthrtut Perl threads tutorial
99
100 perlport Perl portability guide
d396a558 101 perllocale Perl locale support
07fcf8ff 102 perluniintro Perl Unicode introduction
41630250 103 perlunicode Perl Unicode support
3426ea3d 104 perlunifaq Perl Unicode FAQ
ba634883 105 perluniprops Index of Unicode Version 6.0.0 properties in Perl
aadaa455 106 perlunitut Perl Unicode tutorial
d396a558 107 perlebcdic Considerations for running Perl on EBCDIC platforms
c2e66d9e 108
d396a558 109 perlsec Perl security
4755096e 110
c2e66d9e 111 perlmod Perl modules: how they work
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112 perlmodlib Perl modules: how to write and use
113 perlmodstyle Perl modules: how to write modules with style
fd7b6849 114 perlmodinstall Perl modules: how to install from CPAN
c2e66d9e 115 perlnewmod Perl modules: preparing a new module for distribution
a550ee30 116 perlpragma Perl modules: writing a user pragma
760ac839 117
fd7b6849 118 perlutil utilities packaged with the Perl distribution
760ac839 119
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120 perlfilter Perl source filters
121
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122 perldtrace Perl's support for DTrace
123
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124 perlglossary Perl Glossary
125
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126=head2 Internals and C Language Interface
127
fb9cefb4 128 perlembed Perl ways to embed perl in your C or C++ application
41630250 129 perldebguts Perl debugging guts and tips
fb9cefb4 130 perlxstut Perl XS tutorial
4755096e 131 perlxs Perl XS application programming interface
f40a6c71 132 perlclib Internal replacements for standard C library functions
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133 perlguts Perl internal functions for those doing extensions
134 perlcall Perl calling conventions from C
15932acc 135 perlmroapi Perl method resolution plugin interface
108003db 136 perlreapi Perl regular expression plugin interface
b23a565d 137 perlreguts Perl regular expression engine internals
fd7b6849 138
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139 perlapi Perl API listing (autogenerated)
140 perlintern Perl internal functions (autogenerated)
dc5c060f 141 perliol C API for Perl's implementation of IO in Layers
4755096e 142 perlapio Perl internal IO abstraction interface
fd7b6849 143
e8cd7eae 144 perlhack Perl hackers guide
04c692a8 145 perlsource Guide to the Perl source tree
1c2e8cca 146 perlinterp Overview of the Perl interpreter source and how it works
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147 perlhacktut Walk through the creation of a simple C code patch
148 perlhacktips Tips for Perl core C code hacking
cb8a010e 149 perlpolicy Perl development policies
04c692a8 150 perlgit Using git with the Perl repository
4755096e 151
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152=head2 Miscellaneous
153
154 perlbook Perl book information
cbd87e7e 155 perlcommunity Perl community information
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156 perltodo Perl things to do
157
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158 perldoc Look up Perl documentation in Pod format
159
fb9cefb4 160 perlhist Perl history records
bdfb6cc8 161 perldelta Perl changes since previous version
f25d4e05 162 perl5152delta Perl changes in version 5.15.2
5438d4b8 163 perl5151delta Perl changes in version 5.15.1
0890f1a5 164 perl5150delta Perl changes in version 5.15.0
10288c7a 165 perl5141delta Perl changes in version 5.14.1
066dc4d9 166 perl5140delta Perl changes in version 5.14.0
0b67f426 167 perl5124delta Perl changes in version 5.12.4
6c5f5efa 168 perl5123delta Perl changes in version 5.12.3
e71d1a7d 169 perl5122delta Perl changes in version 5.12.2
bdfb6cc8 170 perl5121delta Perl changes in version 5.12.1
20d57231 171 perl5120delta Perl changes in version 5.12.0
7cdf958d 172 perl5101delta Perl changes in version 5.10.1
7120b314 173 perl5100delta Perl changes in version 5.10.0
fc5be808 174 perl589delta Perl changes in version 5.8.9
c11a53c6 175 perl588delta Perl changes in version 5.8.8
315ba985 176 perl587delta Perl changes in version 5.8.7
e4bb216d 177 perl586delta Perl changes in version 5.8.6
07e9b5fe 178 perl585delta Perl changes in version 5.8.5
5f15c94e 179 perl584delta Perl changes in version 5.8.4
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180 perl583delta Perl changes in version 5.8.3
181 perl582delta Perl changes in version 5.8.2
b6235c4f 182 perl581delta Perl changes in version 5.8.1
2e038148 183 perl58delta Perl changes in version 5.8.0
493a87da 184 perl561delta Perl changes in version 5.6.1
41630250 185 perl56delta Perl changes in version 5.6
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186 perl5005delta Perl changes in version 5.005
187 perl5004delta Perl changes in version 5.004
d516a115 188
42e73e1c 189 perlexperiment A listing of experimental features in Perl
190
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191 perlartistic Perl Artistic License
192 perlgpl GNU General Public License
193
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194=head2 Language-Specific
195
196 perlcn Perl for Simplified Chinese (in EUC-CN)
197 perljp Perl for Japanese (in EUC-JP)
198 perlko Perl for Korean (in EUC-KR)
199 perltw Perl for Traditional Chinese (in Big5)
200
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201=head2 Platform-Specific
202
37d4d706 203 perlaix Perl notes for AIX
a83b6f46 204 perlamiga Perl notes for AmigaOS
a83b6f46 205 perlbeos Perl notes for BeOS
dc5c060f 206 perlbs2000 Perl notes for POSIX-BC BS2000
a1f19229 207 perlce Perl notes for WinCE
49877630 208 perlcygwin Perl notes for Cygwin
245d750e 209 perldgux Perl notes for DG/UX
49877630 210 perldos Perl notes for DOS
9a997319 211 perlepoc Perl notes for EPOC
41630250 212 perlfreebsd Perl notes for FreeBSD
f6706af3 213 perlhaiku Perl notes for Haiku
49877630 214 perlhpux Perl notes for HP-UX
a83b6f46 215 perlhurd Perl notes for Hurd
469e7be4 216 perlirix Perl notes for Irix
991e8403 217 perllinux Perl notes for Linux
26d9b02f 218 perlmacos Perl notes for Mac OS (Classic)
0d53b15f 219 perlmacosx Perl notes for Mac OS X
ab648d5e 220 perlmpeix Perl notes for MPE/iX
41630250 221 perlnetware Perl notes for NetWare
b0846812 222 perlopenbsd Perl notes for OpenBSD
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223 perlos2 Perl notes for OS/2
224 perlos390 Perl notes for OS/390
522b859a 225 perlos400 Perl notes for OS/400
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226 perlplan9 Perl notes for Plan 9
227 perlqnx Perl notes for QNX
2f08ed66 228 perlriscos Perl notes for RISC OS
d420ca49 229 perlsolaris Perl notes for Solaris
27da23d5 230 perlsymbian Perl notes for Symbian
772ff3b9 231 perltru64 Perl notes for Tru64
41630250 232 perluts Perl notes for UTS
cbe1151c 233 perlvmesa Perl notes for VM/ESA
49877630 234 perlvms Perl notes for VMS
9a997319 235 perlvos Perl notes for Stratus VOS
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236 perlwin32 Perl notes for Windows
237
35dec5db 238
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239On a Unix-like system, these documentation files will usually also be
240available as manpages for use with the F<man> program.
a0d0e21e 241
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242In general, if something strange has gone wrong with your program and you're
243not sure where you should look for help, try the B<-w> switch first. It will
244often point out exactly where the trouble is.
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245
246=head1 DESCRIPTION
247
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248Perl officially stands for Practical Extraction and Report Language,
249except when it doesn't.
250
72033c14 251Perl was originally a language optimized for scanning arbitrary
a0d0e21e 252text files, extracting information from those text files, and printing
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253reports based on that information. It quickly became a good language
254for many system management tasks. Over the years, Perl has grown into
b6538e4f 255a general-purpose programming language. It's widely used for everything
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256from quick "one-liners" to full-scale application development.
257
258The language is intended to be practical (easy to use, efficient,
259complete) rather than beautiful (tiny, elegant, minimal).
94d58c47 260
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261Perl combines (in the author's opinion, anyway) some of the best
262features of C, B<sed>, B<awk>, and B<sh>, so people familiar with
263those languages should have little difficulty with it. (Language
264historians will also note some vestiges of B<csh>, Pascal, and even
14218588 265BASIC-PLUS.) Expression syntax corresponds closely to C
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266expression syntax. Unlike most Unix utilities, Perl does not
267arbitrarily limit the size of your data--if you've got the memory,
aa689395 268Perl can slurp in your whole file as a single string. Recursion is of
0f31cffe 269unlimited depth. And the tables used by hashes (sometimes called
aa689395 270"associative arrays") grow as necessary to prevent degraded
0f31cffe 271performance. Perl can use sophisticated pattern matching techniques to
14218588 272scan large amounts of data quickly. Although optimized for
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273scanning text, Perl also has many excellent tools for slicing
274and dicing binary data.
aa689395 275
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276But wait, there's more...
277
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278Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete
279rewrite that provides the following additional benefits:
a0d0e21e 280
13a2d996 281=over 4
a0d0e21e 282
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283=item *
284
285modularity and reusability using innumerable modules
a0d0e21e 286
19799a22 287Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>.
a0d0e21e 288
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289=item *
290
291embeddable and extensible
a0d0e21e 292
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293Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>,
294L<perlguts>, and L<xsubpp>.
a0d0e21e 295
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296=item *
297
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298roll-your-own magic variables (including multiple simultaneous DBM
299implementations)
a0d0e21e 300
19799a22 301Described in L<perltie> and L<AnyDBM_File>.
a0d0e21e 302
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303=item *
304
305subroutines can now be overridden, autoloaded, and prototyped
a0d0e21e 306
19799a22 307Described in L<perlsub>.
a0d0e21e 308
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309=item *
310
311arbitrarily nested data structures and anonymous functions
a0d0e21e 312
19799a22 313Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>.
a0d0e21e 314
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315=item *
316
317object-oriented programming
a0d0e21e 318
82e1c0d9 319Described in L<perlobj> and L<perlootut>.
a0d0e21e 320
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321=item *
322
551e1d92 323support for light-weight processes (threads)
a0d0e21e 324
63de3cb2 325Described in L<perlthrtut> and L<threads>.
a0d0e21e 326
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327=item *
328
63de3cb2 329support for Unicode, internationalization, and localization
a0d0e21e 330
63de3cb2 331Described in L<perluniintro>, L<perllocale> and L<Locale::Maketext>.
a0d0e21e 332
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333=item *
334
335lexical scoping
a0d0e21e 336
19799a22 337Described in L<perlsub>.
a0d0e21e 338
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339=item *
340
341regular expression enhancements
a0d0e21e 342
19799a22 343Described in L<perlre>, with additional examples in L<perlop>.
a0d0e21e 344
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345=item *
346
347enhanced debugger and interactive Perl environment,
348with integrated editor support
a0d0e21e 349
f6b3c421 350Described in L<perldebtut>, L<perldebug> and L<perldebguts>.
a0d0e21e 351
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352=item *
353
354POSIX 1003.1 compliant library
5f05dabc 355
19799a22 356Described in L<POSIX>.
5f05dabc 357
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358=back
359
68dc0745 360Okay, that's I<definitely> enough hype.
a0d0e21e 361
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362=head1 AVAILABILITY
363
14218588 364Perl is available for most operating systems, including virtually
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365all Unix-like platforms. See L<perlport/"Supported Platforms">
366for a listing.
8bc4a6bb 367
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368=head1 ENVIRONMENT
369
1e422769 370See L<perlrun>.
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371
372=head1 AUTHOR
373
19799a22 374Larry Wall <larry@wall.org>, with the help of oodles of other folks.
a0d0e21e 375
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376If your Perl success stories and testimonials may be of help to others
377who wish to advocate the use of Perl in their applications,
378or if you wish to simply express your gratitude to Larry and the
19799a22 379Perl developers, please write to perl-thanks@perl.org .
a99b1639 380
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381=head1 FILES
382
5f05dabc 383 "@INC" locations of perl libraries
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384
385=head1 SEE ALSO
386
c5f69108 387 http://www.perl.org/ the Perl homepage
da9e6348 388 http://www.perl.com/ Perl articles (O'Reilly)
f6b3c421 389 http://www.cpan.org/ the Comprehensive Perl Archive
c5f69108 390 http://www.pm.org/ the Perl Mongers
19799a22 391
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392=head1 DIAGNOSTICS
393
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394The C<use warnings> pragma (and the B<-w> switch) produces some
395lovely diagnostics.
a0d0e21e 396
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397See L<perldiag> for explanations of all Perl's diagnostics. The C<use
398diagnostics> pragma automatically turns Perl's normally terse warnings
399and errors into these longer forms.
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400
401Compilation errors will tell you the line number of the error, with an
402indication of the next token or token type that was to be examined.
14218588 403(In a script passed to Perl via B<-e> switches, each
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404B<-e> is counted as one line.)
405
406Setuid scripts have additional constraints that can produce error
407messages such as "Insecure dependency". See L<perlsec>.
408
409Did we mention that you should definitely consider using the B<-w>
410switch?
411
412=head1 BUGS
413
414The B<-w> switch is not mandatory.
415
416Perl is at the mercy of your machine's definitions of various
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417operations such as type casting, atof(), and floating-point
418output with sprintf().
a0d0e21e 419
748a9306 420If your stdio requires a seek or eof between reads and writes on a
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421particular stream, so does Perl. (This doesn't apply to sysread()
422and syswrite().)
423
424While none of the built-in data types have any arbitrary size limits
425(apart from memory size), there are still a few arbitrary limits: a
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426given variable name may not be longer than 251 characters. Line numbers
427displayed by diagnostics are internally stored as short integers,
428so they are limited to a maximum of 65535 (higher numbers usually being
429affected by wraparound).
a0d0e21e 430
b0607b7a 431You may mail your bug reports (be sure to include full configuration
19799a22 432information as output by the myconfig program in the perl source
7f2de2d2 433tree, or by C<perl -V>) to perlbug@perl.org . If you've succeeded
7f89f796 434in compiling perl, the L<perlbug> script in the F<utils/> subdirectory
19799a22 435can be used to help mail in a bug report.
4633a7c4 436
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437Perl actually stands for Pathologically Eclectic Rubbish Lister, but
438don't tell anyone I said that.
439
440=head1 NOTES
441
442The Perl motto is "There's more than one way to do it." Divining
443how many more is left as an exercise to the reader.
444
4633a7c4 445The three principal virtues of a programmer are Laziness,
a0d0e21e 446Impatience, and Hubris. See the Camel Book for why.
16d20bd9 447