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a0d0e21e LW |
1 | =head1 NAME |
2 | ||
3 | perl - Practical Extraction and Report Language | |
4 | ||
5 | =head1 SYNOPSIS | |
6 | ||
94d58c47 | 7 | B<perl> S<[ B<-sTuU> ]> |
8 | S<[ B<-hv> ] [ B<-V>[:I<configvar>] ]> | |
9 | S<[ B<-cw> ] [ B<-d>[:I<debugger>] ] [ B<-D>[I<number/list>] ]> | |
10 | S<[ B<-pna> ] [ B<-F>I<pattern> ] [ B<-l>[I<octal>] ] [ B<-0>[I<octal>] ]> | |
11 | S<[ B<-I>I<dir> ] [ B<-m>[B<->]I<module> ] [ B<-M>[B<->]I<'module...'> ]> | |
12 | S<[ B<-P> ]> | |
13 | S<[ B<-S> ]> | |
14 | S<[ B<-x>[I<dir>] ]> | |
15 | S<[ B<-i>[I<extension>] ]> | |
16 | S<[ B<-e> I<'command'> ] [ B<--> ] [ I<programfile> ] [ I<argument> ]...> | |
c07a80fd | 17 | |
a0d0e21e LW |
18 | For ease of access, the Perl manual has been split up into a number |
19 | of sections: | |
20 | ||
fb9cefb4 GS |
21 | perl Perl overview (this section) |
22 | perldelta Perl changes since previous version | |
9bc80687 GS |
23 | perl5005delta Perl changes in version 5.005 |
24 | perl5004delta Perl changes in version 5.004 | |
fb9cefb4 GS |
25 | perlfaq Perl frequently asked questions |
26 | perltoc Perl documentation table of contents | |
760ac839 | 27 | |
fb9cefb4 GS |
28 | perldata Perl data structures |
29 | perlsyn Perl syntax | |
30 | perlop Perl operators and precedence | |
31 | perlre Perl regular expressions | |
32 | perlrun Perl execution and options | |
33 | perlfunc Perl builtin functions | |
2605996a | 34 | perlopentut Perl open() tutorial |
fb9cefb4 GS |
35 | perlvar Perl predefined variables |
36 | perlsub Perl subroutines | |
37 | perlmod Perl modules: how they work | |
38 | perlmodlib Perl modules: how to write and use | |
39 | perlmodinstall Perl modules: how to install from CPAN | |
40 | perlform Perl formats | |
41 | perllocale Perl locale support | |
760ac839 | 42 | |
fb9cefb4 | 43 | perlref Perl references |
a1e2a320 | 44 | perlreftut Perl references short introduction |
fb9cefb4 GS |
45 | perldsc Perl data structures intro |
46 | perllol Perl data structures: lists of lists | |
47 | perltoot Perl OO tutorial | |
48 | perlobj Perl objects | |
49 | perltie Perl objects hidden behind simple variables | |
50 | perlbot Perl OO tricks and examples | |
51 | perlipc Perl interprocess communication | |
2605996a | 52 | perlthrtut Perl threads tutorial |
9fe6733a | 53 | perldbmfilter Perl DBM Filters |
760ac839 | 54 | |
fb9cefb4 GS |
55 | perldebug Perl debugging |
56 | perldiag Perl diagnostic messages | |
57 | perlsec Perl security | |
58 | perltrap Perl traps for the unwary | |
59 | perlport Perl portability guide | |
60 | perlstyle Perl style guide | |
760ac839 | 61 | |
fb9cefb4 GS |
62 | perlpod Perl plain old documentation |
63 | perlbook Perl book information | |
760ac839 | 64 | |
fb9cefb4 GS |
65 | perlembed Perl ways to embed perl in your C or C++ application |
66 | perlapio Perl internal IO abstraction interface | |
67 | perlxs Perl XS application programming interface | |
68 | perlxstut Perl XS tutorial | |
69 | perlguts Perl internal functions for those doing extensions | |
70 | perlcall Perl calling conventions from C | |
a0d0e21e | 71 | |
e50bb9a1 | 72 | perltodo Perl things to do |
fb9cefb4 | 73 | perlhist Perl history records |
d516a115 | 74 | |
a0d0e21e LW |
75 | (If you're intending to read these straight through for the first time, |
76 | the suggested order will tend to reduce the number of forward references.) | |
77 | ||
fc952dec CS |
78 | By default, all of the above manpages are installed in the |
79 | F</usr/local/man/> directory. | |
80 | ||
81 | Extensive additional documentation for Perl modules is available. The | |
82 | default configuration for perl will place this additional documentation | |
83 | in the F</usr/local/lib/perl5/man> directory (or else in the F<man> | |
84 | subdirectory of the Perl library directory). Some of this additional | |
85 | documentation is distributed standard with Perl, but you'll also find | |
86 | documentation for third-party modules there. | |
87 | ||
88 | You should be able to view Perl's documentation with your man(1) | |
89 | program by including the proper directories in the appropriate start-up | |
90 | files, or in the MANPATH environment variable. To find out where the | |
91 | configuration has installed the manpages, type: | |
16d20bd9 | 92 | |
760ac839 | 93 | perl -V:man.dir |
16d20bd9 | 94 | |
fc952dec CS |
95 | If the directories have a common stem, such as F</usr/local/man/man1> |
96 | and F</usr/local/man/man3>, you need only to add that stem | |
97 | (F</usr/local/man>) to your man(1) configuration files or your MANPATH | |
98 | environment variable. If they do not share a stem, you'll have to add | |
99 | both stems. | |
16d20bd9 AD |
100 | |
101 | If that doesn't work for some reason, you can still use the | |
4633a7c4 LW |
102 | supplied F<perldoc> script to view module information. You might |
103 | also look into getting a replacement man program. | |
16d20bd9 | 104 | |
a0d0e21e LW |
105 | If something strange has gone wrong with your program and you're not |
106 | sure where you should look for help, try the B<-w> switch first. It | |
107 | will often point out exactly where the trouble is. | |
108 | ||
109 | =head1 DESCRIPTION | |
110 | ||
5f05dabc | 111 | Perl is a language optimized for scanning arbitrary |
a0d0e21e LW |
112 | text files, extracting information from those text files, and printing |
113 | reports based on that information. It's also a good language for many | |
114 | system management tasks. The language is intended to be practical | |
115 | (easy to use, efficient, complete) rather than beautiful (tiny, | |
94d58c47 | 116 | elegant, minimal). |
117 | ||
aa689395 | 118 | Perl combines (in the author's opinion, anyway) some of the best |
119 | features of C, B<sed>, B<awk>, and B<sh>, so people familiar with | |
120 | those languages should have little difficulty with it. (Language | |
121 | historians will also note some vestiges of B<csh>, Pascal, and even | |
122 | BASIC-PLUS.) Expression syntax corresponds quite closely to C | |
a0d0e21e LW |
123 | expression syntax. Unlike most Unix utilities, Perl does not |
124 | arbitrarily limit the size of your data--if you've got the memory, | |
aa689395 | 125 | Perl can slurp in your whole file as a single string. Recursion is of |
0f31cffe | 126 | unlimited depth. And the tables used by hashes (sometimes called |
aa689395 | 127 | "associative arrays") grow as necessary to prevent degraded |
0f31cffe | 128 | performance. Perl can use sophisticated pattern matching techniques to |
aa689395 | 129 | scan large amounts of data very quickly. Although optimized for |
130 | scanning text, Perl can also deal with binary data, and can make dbm | |
131 | files look like hashes. Setuid Perl scripts are safer than C programs | |
132 | through a dataflow tracing mechanism which prevents many stupid | |
133 | security holes. | |
134 | ||
135 | If you have a problem that would ordinarily use B<sed> or B<awk> or | |
136 | B<sh>, but it exceeds their capabilities or must run a little faster, | |
137 | and you don't want to write the silly thing in C, then Perl may be for | |
138 | you. There are also translators to turn your B<sed> and B<awk> | |
139 | scripts into Perl scripts. | |
a0d0e21e LW |
140 | |
141 | But wait, there's more... | |
142 | ||
143 | Perl version 5 is nearly a complete rewrite, and provides | |
144 | the following additional benefits: | |
145 | ||
146 | =over 5 | |
147 | ||
148 | =item * Many usability enhancements | |
149 | ||
150 | It is now possible to write much more readable Perl code (even within | |
151 | regular expressions). Formerly cryptic variable names can be replaced | |
152 | by mnemonic identifiers. Error messages are more informative, and the | |
153 | optional warnings will catch many of the mistakes a novice might make. | |
154 | This cannot be stressed enough. Whenever you get mysterious behavior, | |
155 | try the B<-w> switch!!! Whenever you don't get mysterious behavior, | |
156 | try using B<-w> anyway. | |
157 | ||
158 | =item * Simplified grammar | |
159 | ||
160 | The new yacc grammar is one half the size of the old one. Many of the | |
161 | arbitrary grammar rules have been regularized. The number of reserved | |
162 | words has been cut by 2/3. Despite this, nearly all old Perl scripts | |
163 | will continue to work unchanged. | |
164 | ||
165 | =item * Lexical scoping | |
166 | ||
167 | Perl variables may now be declared within a lexical scope, like "auto" | |
168 | variables in C. Not only is this more efficient, but it contributes | |
fc952dec | 169 | to better privacy for "programming in the large". Anonymous |
5f05dabc | 170 | subroutines exhibit deep binding of lexical variables (closures). |
a0d0e21e LW |
171 | |
172 | =item * Arbitrarily nested data structures | |
173 | ||
174 | Any scalar value, including any array element, may now contain a | |
175 | reference to any other variable or subroutine. You can easily create | |
176 | anonymous variables and subroutines. Perl manages your reference | |
177 | counts for you. | |
178 | ||
179 | =item * Modularity and reusability | |
180 | ||
181 | The Perl library is now defined in terms of modules which can be easily | |
182 | shared among various packages. A package may choose to import all or a | |
183 | portion of a module's published interface. Pragmas (that is, compiler | |
184 | directives) are defined and used by the same mechanism. | |
185 | ||
186 | =item * Object-oriented programming | |
187 | ||
188 | A package can function as a class. Dynamic multiple inheritance and | |
189 | virtual methods are supported in a straightforward manner and with very | |
190 | little new syntax. Filehandles may now be treated as objects. | |
191 | ||
c07a80fd | 192 | =item * Embeddable and Extensible |
a0d0e21e LW |
193 | |
194 | Perl may now be embedded easily in your C or C++ application, and can | |
195 | either call or be called by your routines through a documented | |
196 | interface. The XS preprocessor is provided to make it easy to glue | |
197 | your C or C++ routines into Perl. Dynamic loading of modules is | |
5f05dabc | 198 | supported, and Perl itself can be made into a dynamic library. |
a0d0e21e LW |
199 | |
200 | =item * POSIX compliant | |
201 | ||
202 | A major new module is the POSIX module, which provides access to all | |
203 | available POSIX routines and definitions, via object classes where | |
204 | appropriate. | |
205 | ||
206 | =item * Package constructors and destructors | |
207 | ||
208 | The new BEGIN and END blocks provide means to capture control as | |
209 | a package is being compiled, and after the program exits. As a | |
210 | degenerate case they work just like awk's BEGIN and END when you | |
211 | use the B<-p> or B<-n> switches. | |
212 | ||
213 | =item * Multiple simultaneous DBM implementations | |
214 | ||
215 | A Perl program may now access DBM, NDBM, SDBM, GDBM, and Berkeley DB | |
216 | files from the same script simultaneously. In fact, the old dbmopen | |
217 | interface has been generalized to allow any variable to be tied | |
218 | to an object class which defines its access methods. | |
219 | ||
220 | =item * Subroutine definitions may now be autoloaded | |
221 | ||
222 | In fact, the AUTOLOAD mechanism also allows you to define any arbitrary | |
5f05dabc | 223 | semantics for undefined subroutine calls. It's not for just autoloading. |
a0d0e21e LW |
224 | |
225 | =item * Regular expression enhancements | |
226 | ||
fc952dec | 227 | You can now specify nongreedy quantifiers. You can now do grouping |
a0d0e21e LW |
228 | without creating a backreference. You can now write regular expressions |
229 | with embedded whitespace and comments for readability. A consistent | |
230 | extensibility mechanism has been added that is upwardly compatible with | |
231 | all old regular expressions. | |
232 | ||
5f05dabc | 233 | =item * Innumerable Unbundled Modules |
234 | ||
f102b883 TC |
235 | The Comprehensive Perl Archive Network described in L<perlmodlib> |
236 | contains hundreds of plug-and-play modules full of reusable code. | |
237 | See F<http://www.perl.com/CPAN> for a site near you. | |
5f05dabc | 238 | |
239 | =item * Compilability | |
240 | ||
241 | While not yet in full production mode, a working perl-to-C compiler | |
fc952dec | 242 | does exist. It can generate portable byte code, simple C, or |
5f05dabc | 243 | optimized C code. |
244 | ||
a0d0e21e LW |
245 | =back |
246 | ||
68dc0745 | 247 | Okay, that's I<definitely> enough hype. |
a0d0e21e | 248 | |
8e465e4e JH |
249 | =head1 AVAILABILITY |
250 | ||
251 | Perl is available for the vast majority of operating system platforms, | |
252 | including most Unix-like platforms. The following situation is as of | |
253 | February 1999 and Perl 5.005_03. | |
254 | ||
255 | The following platforms are able to build Perl from the standard | |
256 | source code distribution available at | |
257 | F<http://www.perl.com/CPAN/src/index.html> | |
258 | ||
58493fc4 JH |
259 | AIX Linux SCO ODT/OSR |
260 | A/UX MachTen Solaris | |
261 | BeOS MPE/iX SunOS | |
262 | BSD/OS NetBSD SVR4 | |
263 | DG/UX NextSTEP Tru64 UNIX 3) | |
264 | DomainOS OpenBSD Ultrix | |
265 | DOS DJGPP 1) OpenSTEP UNICOS | |
266 | DYNIX/ptx OS/2 VMS | |
267 | FreeBSD OS390 2) VOS | |
268 | HP-UX PowerMAX Windows 3.1 1) | |
269 | Hurd QNX Windows 95 1) 4) | |
270 | IRIX Windows 98 1) 4) | |
271 | Windows NT 1) 4) | |
8e465e4e JH |
272 | |
273 | 1) in DOS mode either the DOS or OS/2 ports can be used | |
58493fc4 JH |
274 | 2) formerly known as MVS |
275 | 3) formerly known as Digital UNIX and before that DEC OSF/1 | |
276 | 4) compilers: Borland, Cygwin32, Mingw32 EGCS/GCC, VC++ | |
277 | ||
8e465e4e JH |
278 | The following platforms have been known to build Perl from the source |
279 | but for the Perl release 5.005_03 we haven't been able to verify them, | |
280 | either because the hardware/software platforms are rather rare or | |
2e04d155 | 281 | because we don't have an active champion on these platforms, or both. |
8e465e4e JH |
282 | |
283 | 3b1 FPS Plan 9 | |
04251ce8 JH |
284 | AmigaOS GENIX PowerUX |
285 | ConvexOS Greenhills RISC/os | |
286 | CX/UX ISC Stellar | |
287 | DC/OSx MachTen 68k SVR2 | |
288 | DDE SMES MiNT TI1500 | |
82cda36e JH |
289 | DOS EMX MPC TitanOS |
290 | Dynix NEWS-OS UNICOS/mk | |
291 | EP/IX Opus Unisys Dynix | |
292 | ESIX Unixware | |
8e465e4e JH |
293 | |
294 | The following platforms are planned to be supported in the standard | |
2e04d155 | 295 | source code distribution of the Perl release 5.006 but are not |
8e465e4e JH |
296 | supported in the Perl release 5.005_03: |
297 | ||
298 | BS2000 | |
00ad96e1 JH |
299 | Netware |
300 | Rhapsody | |
8e465e4e JH |
301 | VM/ESA |
302 | ||
303 | The following platforms have their own source code distributions and | |
304 | binaries available via F<http://www.perl.com/CPAN/ports/index.html>. | |
305 | ||
306 | Perl release | |
307 | ||
308 | AS/400 5.003 | |
2e04d155 | 309 | MacOS 5.004 |
04251ce8 | 310 | Netware 5.003_07 |
8e465e4e JH |
311 | Tandem Guardian 5.004 |
312 | ||
313 | The following platforms have only binaries available via | |
314 | F<http://www.perl.com/CPAN/ports/index.html>. | |
315 | ||
316 | Perl release | |
317 | ||
d845c4a6 | 318 | Acorn RISCOS 5.005_02 |
8e465e4e JH |
319 | AOS 5.002 |
320 | LynxOS 5.004_02 | |
8e465e4e | 321 | |
a0d0e21e LW |
322 | =head1 ENVIRONMENT |
323 | ||
1e422769 | 324 | See L<perlrun>. |
a0d0e21e LW |
325 | |
326 | =head1 AUTHOR | |
327 | ||
9607fc9c | 328 | Larry Wall <F<larry@wall.org>>, with the help of oodles of other folks. |
a0d0e21e | 329 | |
a99b1639 TP |
330 | If your Perl success stories and testimonials may be of help to others |
331 | who wish to advocate the use of Perl in their applications, | |
332 | or if you wish to simply express your gratitude to Larry and the | |
333 | Perl developers, please write to <F<perl-thanks@perl.org>>. | |
334 | ||
a0d0e21e LW |
335 | =head1 FILES |
336 | ||
5f05dabc | 337 | "@INC" locations of perl libraries |
a0d0e21e LW |
338 | |
339 | =head1 SEE ALSO | |
340 | ||
341 | a2p awk to perl translator | |
4633a7c4 | 342 | |
a0d0e21e LW |
343 | s2p sed to perl translator |
344 | ||
345 | =head1 DIAGNOSTICS | |
346 | ||
347 | The B<-w> switch produces some lovely diagnostics. | |
348 | ||
5a964f20 TC |
349 | See L<perldiag> for explanations of all Perl's diagnostics. The C<use |
350 | diagnostics> pragma automatically turns Perl's normally terse warnings | |
351 | and errors into these longer forms. | |
a0d0e21e LW |
352 | |
353 | Compilation errors will tell you the line number of the error, with an | |
354 | indication of the next token or token type that was to be examined. | |
355 | (In the case of a script passed to Perl via B<-e> switches, each | |
356 | B<-e> is counted as one line.) | |
357 | ||
358 | Setuid scripts have additional constraints that can produce error | |
359 | messages such as "Insecure dependency". See L<perlsec>. | |
360 | ||
361 | Did we mention that you should definitely consider using the B<-w> | |
362 | switch? | |
363 | ||
364 | =head1 BUGS | |
365 | ||
366 | The B<-w> switch is not mandatory. | |
367 | ||
368 | Perl is at the mercy of your machine's definitions of various | |
1b3f7d21 CS |
369 | operations such as type casting, atof(), and floating-point |
370 | output with sprintf(). | |
a0d0e21e | 371 | |
748a9306 | 372 | If your stdio requires a seek or eof between reads and writes on a |
a0d0e21e LW |
373 | particular stream, so does Perl. (This doesn't apply to sysread() |
374 | and syswrite().) | |
375 | ||
376 | While none of the built-in data types have any arbitrary size limits | |
377 | (apart from memory size), there are still a few arbitrary limits: a | |
a30ac152 GS |
378 | given variable name may not be longer than 251 characters. Line numbers |
379 | displayed by diagnostics are internally stored as short integers, | |
380 | so they are limited to a maximum of 65535 (higher numbers usually being | |
381 | affected by wraparound). | |
a0d0e21e | 382 | |
b0607b7a LV |
383 | You may mail your bug reports (be sure to include full configuration |
384 | information as output by the myconfig program in the perl source tree, | |
9607fc9c | 385 | or by C<perl -V>) to <F<perlbug@perl.com>>. |
c07a80fd | 386 | If you've succeeded in compiling perl, the perlbug script in the utils/ |
387 | subdirectory can be used to help mail in a bug report. | |
4633a7c4 | 388 | |
a0d0e21e LW |
389 | Perl actually stands for Pathologically Eclectic Rubbish Lister, but |
390 | don't tell anyone I said that. | |
391 | ||
392 | =head1 NOTES | |
393 | ||
394 | The Perl motto is "There's more than one way to do it." Divining | |
395 | how many more is left as an exercise to the reader. | |
396 | ||
4633a7c4 | 397 | The three principal virtues of a programmer are Laziness, |
a0d0e21e | 398 | Impatience, and Hubris. See the Camel Book for why. |
16d20bd9 | 399 |