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1 | =head1 NAME |
2 | |
3 | perl - Practical Extraction and Report Language |
4 | |
5 | =head1 SYNOPSIS |
6 | |
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7 | B<perl> S<[ B<-sTuU> ]> S<[ B<-hv> ] [ B<-V>[:I<configvar>] ]> |
8 | S<[ B<-cw> ] [ B<-d>[:I<debugger>] ] [ B<-D>[I<number/list>] ]> |
9 | S<[ B<-pna> ] [ B<-F>I<pattern> ] [ B<-l>[I<octal>] ] [ B<-0>[I<octal>] ]> |
10 | S<[ B<-I>I<dir> ] [ B<-m>[B<->]I<module> ] [ B<-M>[B<->]I<'module...'> ]> |
11 | S<[ B<-P> ]> S<[ B<-S> ]> S<[ B<-x>[I<dir>] ]> |
12 | S<[ B<-i>[I<extension>] ]> S<[ B<-e> I<'command'> ] |
13 | [ B<--> ] [ I<programfile> ] [ I<argument> ]...> |
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14 | |
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15 | For ease of access, the Perl manual has been split up into several |
16 | sections: |
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17 | |
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18 | perl Perl overview (this section) |
19 | perldelta Perl changes since previous version |
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20 | perl5005delta Perl changes in version 5.005 |
21 | perl5004delta Perl changes in version 5.004 |
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22 | perlfaq Perl frequently asked questions |
23 | perltoc Perl documentation table of contents |
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24 | |
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25 | perldata Perl data structures |
26 | perlsyn Perl syntax |
27 | perlop Perl operators and precedence |
28 | perlre Perl regular expressions |
29 | perlrun Perl execution and options |
30 | perlfunc Perl builtin functions |
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31 | perlopentut Perl open() tutorial |
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32 | perlvar Perl predefined variables |
33 | perlsub Perl subroutines |
34 | perlmod Perl modules: how they work |
35 | perlmodlib Perl modules: how to write and use |
36 | perlmodinstall Perl modules: how to install from CPAN |
37 | perlform Perl formats |
38 | perllocale Perl locale support |
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39 | |
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40 | perlreftut Perl references short introduction |
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41 | perlref Perl references, the rest of the story |
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42 | perldsc Perl data structures intro |
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43 | perllol Perl data structures: arrays of arrays |
44 | perltoot Perl OO tutorial, part 1 |
45 | perltootc Perl OO tutorial, part 2 |
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46 | perlobj Perl objects |
47 | perltie Perl objects hidden behind simple variables |
48 | perlbot Perl OO tricks and examples |
49 | perlipc Perl interprocess communication |
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50 | perlthrtut Perl threads tutorial |
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51 | perldbmfilter Perl DBM Filters |
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52 | |
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53 | perldebug Perl debugging |
54 | perldiag Perl diagnostic messages |
55 | perlsec Perl security |
56 | perltrap Perl traps for the unwary |
57 | perlport Perl portability guide |
58 | perlstyle Perl style guide |
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59 | |
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60 | perlpod Perl plain old documentation |
61 | perlbook Perl book information |
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62 | |
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63 | perlembed Perl ways to embed perl in your C or C++ application |
64 | perlapio Perl internal IO abstraction interface |
65 | perlxs Perl XS application programming interface |
66 | perlxstut Perl XS tutorial |
67 | perlguts Perl internal functions for those doing extensions |
68 | perlcall Perl calling conventions from C |
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69 | |
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70 | perltodo Perl things to do |
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71 | perlhist Perl history records |
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72 | |
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73 | (If you're intending to read these straight through for the first time, |
74 | the suggested order will tend to reduce the number of forward references.) |
75 | |
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76 | By default, the manpages listed above are installed in the |
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77 | F</usr/local/man/> directory. |
78 | |
79 | Extensive additional documentation for Perl modules is available. The |
80 | default configuration for perl will place this additional documentation |
81 | in the F</usr/local/lib/perl5/man> directory (or else in the F<man> |
82 | subdirectory of the Perl library directory). Some of this additional |
83 | documentation is distributed standard with Perl, but you'll also find |
84 | documentation for third-party modules there. |
85 | |
86 | You should be able to view Perl's documentation with your man(1) |
87 | program by including the proper directories in the appropriate start-up |
88 | files, or in the MANPATH environment variable. To find out where the |
89 | configuration has installed the manpages, type: |
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90 | |
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91 | perl -V:man.dir |
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92 | |
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93 | If the directories have a common stem, such as F</usr/local/man/man1> |
94 | and F</usr/local/man/man3>, you need only to add that stem |
95 | (F</usr/local/man>) to your man(1) configuration files or your MANPATH |
96 | environment variable. If they do not share a stem, you'll have to add |
97 | both stems. |
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98 | |
99 | If that doesn't work for some reason, you can still use the |
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100 | supplied F<perldoc> script to view module information. You might |
101 | also look into getting a replacement man program. |
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102 | |
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103 | If something strange has gone wrong with your program and you're not |
104 | sure where you should look for help, try the B<-w> switch first. It |
105 | will often point out exactly where the trouble is. |
106 | |
107 | =head1 DESCRIPTION |
108 | |
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109 | Perl is a language optimized for scanning arbitrary |
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110 | text files, extracting information from those text files, and printing |
111 | reports based on that information. It's also a good language for many |
112 | system management tasks. The language is intended to be practical |
113 | (easy to use, efficient, complete) rather than beautiful (tiny, |
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114 | elegant, minimal). |
115 | |
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116 | Perl combines (in the author's opinion, anyway) some of the best |
117 | features of C, B<sed>, B<awk>, and B<sh>, so people familiar with |
118 | those languages should have little difficulty with it. (Language |
119 | historians will also note some vestiges of B<csh>, Pascal, and even |
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120 | BASIC-PLUS.) Expression syntax corresponds closely to C |
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121 | expression syntax. Unlike most Unix utilities, Perl does not |
122 | arbitrarily limit the size of your data--if you've got the memory, |
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123 | Perl can slurp in your whole file as a single string. Recursion is of |
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124 | unlimited depth. And the tables used by hashes (sometimes called |
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125 | "associative arrays") grow as necessary to prevent degraded |
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126 | performance. Perl can use sophisticated pattern matching techniques to |
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127 | scan large amounts of data quickly. Although optimized for |
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128 | scanning text, Perl can also deal with binary data, and can make dbm |
129 | files look like hashes. Setuid Perl scripts are safer than C programs |
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130 | through a dataflow tracing mechanism that prevents many stupid |
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131 | security holes. |
132 | |
133 | If you have a problem that would ordinarily use B<sed> or B<awk> or |
134 | B<sh>, but it exceeds their capabilities or must run a little faster, |
135 | and you don't want to write the silly thing in C, then Perl may be for |
136 | you. There are also translators to turn your B<sed> and B<awk> |
137 | scripts into Perl scripts. |
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138 | |
139 | But wait, there's more... |
140 | |
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141 | Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete |
142 | rewrite that provides the following additional benefits: |
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143 | |
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144 | =over |
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145 | |
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146 | =item * modularity and reusability using innumerable modules |
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147 | |
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148 | Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>. |
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149 | |
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150 | =item * embeddable and extensible |
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151 | |
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152 | Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>, |
153 | L<perlguts>, and L<xsubpp>. |
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154 | |
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155 | =item * roll-your-own magic variables (including multiple simultaneous DBM implementations) |
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156 | |
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157 | Described in L<perltie> and L<AnyDBM_File>. |
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158 | |
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159 | =item * subroutines can now be overridden, autoloaded, and prototyped |
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160 | |
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161 | Described in L<perlsub>. |
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162 | |
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163 | =item * arbitrarily nested data structures and anonymous functions |
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164 | |
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165 | Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>. |
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166 | |
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167 | =item * object-oriented programming |
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168 | |
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169 | Described in L<perlobj>, L<perltoot>, and L<perlbot>. |
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170 | |
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171 | =item * compilability into C code or Perl bytecode |
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172 | |
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173 | Described in L<B> and L<B::Bytecode>. |
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174 | |
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175 | =item * support for light-weight processes (threads) |
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176 | |
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177 | Described in L<perlthrtut> and L<Thread>. |
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178 | |
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179 | =item * support for internationalization, localization, and Unicode |
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180 | |
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181 | Described in L<perllocale> and L<utf8>. |
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182 | |
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183 | =item * lexical scoping |
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184 | |
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185 | Described in L<perlsub>. |
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186 | |
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187 | =item * regular expression enhancements |
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188 | |
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189 | Described in L<perlre>, with additional examples in L<perlop>. |
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190 | |
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191 | =item * enhanced debugger and interactive Perl environment, with integrated editor support |
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192 | |
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193 | Described in L<perldebug>. |
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194 | |
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195 | =item * POSIX 1003.1 compliant library |
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196 | |
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197 | Described in L<POSIX>. |
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198 | |
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199 | =back |
200 | |
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201 | Okay, that's I<definitely> enough hype. |
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202 | |
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203 | =head1 AVAILABILITY |
204 | |
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205 | Perl is available for most operating systems, including virtually |
206 | all Unix-like platforms. |
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207 | |
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208 | As of May 1999, the following platforms are able to build Perl |
209 | from the standard source code distribution available at |
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210 | http://www.perl.com/CPAN/src/index.html |
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211 | |
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212 | AIX Linux SCO ODT/OSR |
213 | A/UX MachTen Solaris |
214 | BeOS MPE/iX SunOS |
215 | BSD/OS NetBSD SVR4 |
216 | DG/UX NextSTEP Tru64 UNIX 3) |
217 | DomainOS OpenBSD Ultrix |
218 | DOS DJGPP 1) OpenSTEP UNICOS |
219 | DYNIX/ptx OS/2 VMS |
220 | FreeBSD OS390 2) VOS |
221 | HP-UX PowerMAX Windows 3.1 1) |
222 | Hurd QNX Windows 95 1) 4) |
223 | IRIX Windows 98 1) 4) |
224 | Windows NT 1) 4) |
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225 | |
226 | 1) in DOS mode either the DOS or OS/2 ports can be used |
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227 | 2) formerly known as MVS |
228 | 3) formerly known as Digital UNIX and before that DEC OSF/1 |
229 | 4) compilers: Borland, Cygwin32, Mingw32 EGCS/GCC, VC++ |
230 | |
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231 | The following platforms have been known to build Perl from source, |
232 | but we haven't been able to verify their status for the current release, |
233 | either because the hardware/software platforms are rare or |
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234 | because we don't have an active champion on these platforms--or both. |
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235 | |
236 | 3b1 FPS Plan 9 |
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237 | AmigaOS GENIX PowerUX |
238 | ConvexOS Greenhills RISC/os |
239 | CX/UX ISC Stellar |
240 | DC/OSx MachTen 68k SVR2 |
241 | DDE SMES MiNT TI1500 |
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242 | DOS EMX MPC TitanOS |
243 | Dynix NEWS-OS UNICOS/mk |
244 | EP/IX Opus Unisys Dynix |
245 | ESIX Unixware |
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246 | |
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247 | Support for the following platforms is planned for the next major |
248 | Perl release. |
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249 | |
250 | BS2000 |
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251 | Netware |
252 | Rhapsody |
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253 | VM/ESA |
254 | |
255 | The following platforms have their own source code distributions and |
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256 | binaries available via http://www.perl.com/CPAN/ports/index.html. |
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257 | |
258 | Perl release |
259 | |
260 | AS/400 5.003 |
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261 | MacOS 5.004 |
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262 | Netware 5.003_07 |
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263 | Tandem Guardian 5.004 |
264 | |
265 | The following platforms have only binaries available via |
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266 | http://www.perl.com/CPAN/ports/index.html. |
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267 | |
268 | Perl release |
269 | |
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270 | Acorn RISCOS 5.005_02 |
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271 | AOS 5.002 |
272 | LynxOS 5.004_02 |
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273 | |
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274 | =head1 ENVIRONMENT |
275 | |
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276 | See L<perlrun>. |
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277 | |
278 | =head1 AUTHOR |
279 | |
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280 | Larry Wall <larry@wall.org>, with the help of oodles of other folks. |
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281 | |
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282 | If your Perl success stories and testimonials may be of help to others |
283 | who wish to advocate the use of Perl in their applications, |
284 | or if you wish to simply express your gratitude to Larry and the |
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285 | Perl developers, please write to perl-thanks@perl.org . |
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286 | |
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287 | =head1 FILES |
288 | |
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289 | "@INC" locations of perl libraries |
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290 | |
291 | =head1 SEE ALSO |
292 | |
293 | a2p awk to perl translator |
294 | s2p sed to perl translator |
295 | |
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296 | http://www.perl.com/ the Perl Home Page |
297 | http://www.perl.com/CPAN the Comphrehensive Perl Archive |
298 | |
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299 | =head1 DIAGNOSTICS |
300 | |
301 | The B<-w> switch produces some lovely diagnostics. |
302 | |
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303 | See L<perldiag> for explanations of all Perl's diagnostics. The C<use |
304 | diagnostics> pragma automatically turns Perl's normally terse warnings |
305 | and errors into these longer forms. |
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306 | |
307 | Compilation errors will tell you the line number of the error, with an |
308 | indication of the next token or token type that was to be examined. |
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309 | (In a script passed to Perl via B<-e> switches, each |
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310 | B<-e> is counted as one line.) |
311 | |
312 | Setuid scripts have additional constraints that can produce error |
313 | messages such as "Insecure dependency". See L<perlsec>. |
314 | |
315 | Did we mention that you should definitely consider using the B<-w> |
316 | switch? |
317 | |
318 | =head1 BUGS |
319 | |
320 | The B<-w> switch is not mandatory. |
321 | |
322 | Perl is at the mercy of your machine's definitions of various |
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323 | operations such as type casting, atof(), and floating-point |
324 | output with sprintf(). |
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325 | |
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326 | If your stdio requires a seek or eof between reads and writes on a |
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327 | particular stream, so does Perl. (This doesn't apply to sysread() |
328 | and syswrite().) |
329 | |
330 | While none of the built-in data types have any arbitrary size limits |
331 | (apart from memory size), there are still a few arbitrary limits: a |
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332 | given variable name may not be longer than 251 characters. Line numbers |
333 | displayed by diagnostics are internally stored as short integers, |
334 | so they are limited to a maximum of 65535 (higher numbers usually being |
335 | affected by wraparound). |
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336 | |
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337 | You may mail your bug reports (be sure to include full configuration |
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338 | information as output by the myconfig program in the perl source |
339 | tree, or by C<perl -V>) to perlbug@perl.com . If you've succeeded |
340 | in compiling perl, the perlbug script in the utils/ subdirectory |
341 | can be used to help mail in a bug report. |
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342 | |
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343 | Perl actually stands for Pathologically Eclectic Rubbish Lister, but |
344 | don't tell anyone I said that. |
345 | |
346 | =head1 NOTES |
347 | |
348 | The Perl motto is "There's more than one way to do it." Divining |
349 | how many more is left as an exercise to the reader. |
350 | |
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351 | The three principal virtues of a programmer are Laziness, |
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352 | Impatience, and Hubris. See the Camel Book for why. |
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353 | |