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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 sections: |
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16 | |
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17 | perl Perl overview (this section) |
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18 | perlfaq Perl frequently asked questions |
19 | perltoc Perl documentation table of contents |
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20 | perlbook Perl book information |
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21 | |
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22 | perlsyn Perl syntax |
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23 | perldata Perl data structures |
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24 | perlop Perl operators and precedence |
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25 | perlsub Perl subroutines |
26 | perlfunc Perl builtin functions |
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27 | perlreftut Perl references short introduction |
28 | perldsc Perl data structures intro |
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29 | perlrequick Perl regular expressions quick start |
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30 | perlpod Perl plain old documentation |
31 | perlstyle Perl style guide |
32 | perltrap Perl traps for the unwary |
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33 | |
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34 | perlrun Perl execution and options |
35 | perldiag Perl diagnostic messages |
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36 | perllexwarn Perl warnings and their control |
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37 | perldebtut Perl debugging tutorial |
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38 | perldebug Perl debugging |
39 | |
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40 | perlvar Perl predefined variables |
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41 | perllol Perl data structures: arrays of arrays |
42 | perlopentut Perl open() tutorial |
43 | perlretut Perl regular expressions tutorial |
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44 | |
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45 | perlre Perl regular expressions, the rest of the story |
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46 | perlref Perl references, the rest of the story |
47 | |
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48 | perlform Perl formats |
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49 | |
50 | perlboot Perl OO tutorial for beginners |
51 | perltoot Perl OO tutorial, part 1 |
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52 | perltooc Perl OO tutorial, part 2 |
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53 | perlobj Perl objects |
54 | perlbot Perl OO tricks and examples |
55 | perltie Perl objects hidden behind simple variables |
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56 | |
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57 | perlipc Perl interprocess communication |
58 | perlfork Perl fork() information |
59 | perlnumber Perl number semantics |
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60 | |
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61 | perlthrtut Perl threads tutorial |
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62 | perlothrtut Perl old threads tutorial |
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63 | |
64 | perlport Perl portability guide |
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65 | perllocale Perl locale support |
66 | perlunicode Perl unicode support |
67 | perlebcdic Considerations for running Perl on EBCDIC platforms |
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68 | |
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69 | perlsec Perl security |
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70 | |
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71 | perlmod Perl modules: how they work |
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72 | perlmodinstall Perl modules: how to install from CPAN |
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73 | perlmodlib Perl modules: how to write and use |
74 | perlmodstyle Perl modules: how to write modules with style |
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75 | perlnewmod Perl modules: preparing a new module for distribution |
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76 | |
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77 | perlfaq1 General Questions About Perl |
78 | perlfaq2 Obtaining and Learning about Perl |
79 | perlfaq3 Programming Tools |
80 | perlfaq4 Data Manipulation |
81 | perlfaq5 Files and Formats |
82 | perlfaq6 Regexes |
83 | perlfaq7 Perl Language Issues |
84 | perlfaq8 System Interaction |
85 | perlfaq9 Networking |
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86 | |
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87 | perlcompile Perl compiler suite intro |
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88 | |
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89 | perlembed Perl ways to embed perl in your C or C++ application |
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90 | perldebguts Perl debugging guts and tips |
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91 | perlxstut Perl XS tutorial |
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92 | perlxs Perl XS application programming interface |
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93 | perlclib Internal replacements for standard C library functions |
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94 | perlguts Perl internal functions for those doing extensions |
95 | perlcall Perl calling conventions from C |
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96 | perlutil utilities packaged with the Perl distribution |
97 | perlfilter Perl source filters |
98 | perldbmfilter Perl DBM filters |
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99 | perlapi Perl API listing (autogenerated) |
100 | perlintern Perl internal functions (autogenerated) |
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101 | perliol C API for Perl's implementation of IO in Layers |
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102 | perlapio Perl internal IO abstraction interface |
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103 | perltodo Perl things to do |
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104 | perlhack Perl hackers guide |
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105 | |
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106 | perlhist Perl history records |
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107 | perldelta Perl changes since previous version |
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108 | perl572delta Perl changes in version 5.7.2 |
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109 | perl571delta Perl changes in version 5.7.1 |
110 | perl570delta Perl changes in version 5.7.0 |
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111 | perl56delta Perl changes in version 5.6 |
112 | perl5005delta Perl changes in version 5.005 |
113 | perl5004delta Perl changes in version 5.004 |
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114 | |
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115 | perlaix Perl notes for AIX |
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116 | perlamiga Perl notes for AmigaOS |
117 | perlapollo Perl notes for Apollo DomainOS |
118 | perlbeos Perl notes for BeOS |
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119 | perlbs2000 Perl notes for POSIX-BC BS2000 |
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120 | perlce Perl notes for WinCE |
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121 | perlcygwin Perl notes for Cygwin |
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122 | perldgux Perl notes for DG/UX |
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123 | perldos Perl notes for DOS |
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124 | perlepoc Perl notes for EPOC |
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125 | perlhpux Perl notes for HP-UX |
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126 | perlhurd Perl notes for Hurd |
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127 | perlmachten Perl notes for Power MachTen |
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128 | perlmacos Perl notes for Mac OS (Classic) |
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129 | perlmint Perl notes for MiNT |
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130 | perlmpeix Perl notes for MPE/iX |
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131 | perlnetware Perl notes for NetWare |
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132 | perlos2 Perl notes for OS/2 |
133 | perlos390 Perl notes for OS/390 |
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134 | perlplan9 Perl notes for Plan 9 |
135 | perlqnx Perl notes for QNX |
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136 | perlsolaris Perl notes for Solaris |
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137 | perltru64 Perl notes for Tru64 |
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138 | perluts Perl notes for UTS |
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139 | perlvmesa Perl notes for VM/ESA |
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140 | perlvms Perl notes for VMS |
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141 | perlvos Perl notes for Stratus VOS |
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142 | perlwin32 Perl notes for Windows |
143 | |
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144 | (If you're intending to read these straight through for the first time, |
145 | the suggested order will tend to reduce the number of forward references.) |
146 | |
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147 | By default, the manpages listed above are installed in the |
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148 | F</usr/local/man/> directory. |
149 | |
150 | Extensive additional documentation for Perl modules is available. The |
151 | default configuration for perl will place this additional documentation |
152 | in the F</usr/local/lib/perl5/man> directory (or else in the F<man> |
153 | subdirectory of the Perl library directory). Some of this additional |
154 | documentation is distributed standard with Perl, but you'll also find |
155 | documentation for third-party modules there. |
156 | |
157 | You should be able to view Perl's documentation with your man(1) |
158 | program by including the proper directories in the appropriate start-up |
159 | files, or in the MANPATH environment variable. To find out where the |
160 | configuration has installed the manpages, type: |
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161 | |
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162 | perl -V:man.dir |
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163 | |
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164 | If the directories have a common stem, such as F</usr/local/man/man1> |
165 | and F</usr/local/man/man3>, you need only to add that stem |
166 | (F</usr/local/man>) to your man(1) configuration files or your MANPATH |
167 | environment variable. If they do not share a stem, you'll have to add |
168 | both stems. |
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169 | |
170 | If that doesn't work for some reason, you can still use the |
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171 | supplied F<perldoc> script to view module information. You might |
172 | also look into getting a replacement man program. |
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173 | |
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174 | If something strange has gone wrong with your program and you're not |
175 | sure where you should look for help, try the B<-w> switch first. It |
176 | will often point out exactly where the trouble is. |
177 | |
178 | =head1 DESCRIPTION |
179 | |
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180 | Perl is a language optimized for scanning arbitrary |
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181 | text files, extracting information from those text files, and printing |
182 | reports based on that information. It's also a good language for many |
183 | system management tasks. The language is intended to be practical |
184 | (easy to use, efficient, complete) rather than beautiful (tiny, |
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185 | elegant, minimal). |
186 | |
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187 | Perl combines (in the author's opinion, anyway) some of the best |
188 | features of C, B<sed>, B<awk>, and B<sh>, so people familiar with |
189 | those languages should have little difficulty with it. (Language |
190 | historians will also note some vestiges of B<csh>, Pascal, and even |
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191 | BASIC-PLUS.) Expression syntax corresponds closely to C |
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192 | expression syntax. Unlike most Unix utilities, Perl does not |
193 | arbitrarily limit the size of your data--if you've got the memory, |
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194 | Perl can slurp in your whole file as a single string. Recursion is of |
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195 | unlimited depth. And the tables used by hashes (sometimes called |
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196 | "associative arrays") grow as necessary to prevent degraded |
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197 | performance. Perl can use sophisticated pattern matching techniques to |
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198 | scan large amounts of data quickly. Although optimized for |
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199 | scanning text, Perl can also deal with binary data, and can make dbm |
200 | files look like hashes. Setuid Perl scripts are safer than C programs |
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201 | through a dataflow tracing mechanism that prevents many stupid |
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202 | security holes. |
203 | |
204 | If you have a problem that would ordinarily use B<sed> or B<awk> or |
205 | B<sh>, but it exceeds their capabilities or must run a little faster, |
206 | and you don't want to write the silly thing in C, then Perl may be for |
207 | you. There are also translators to turn your B<sed> and B<awk> |
208 | scripts into Perl scripts. |
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209 | |
210 | But wait, there's more... |
211 | |
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212 | Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete |
213 | rewrite that provides the following additional benefits: |
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214 | |
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215 | =over 4 |
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216 | |
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217 | =item * |
218 | |
219 | modularity and reusability using innumerable modules |
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220 | |
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221 | Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>. |
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222 | |
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223 | =item * |
224 | |
225 | embeddable and extensible |
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226 | |
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227 | Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>, |
228 | L<perlguts>, and L<xsubpp>. |
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229 | |
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230 | =item * |
231 | |
232 | roll-your-own magic variables (including multiple simultaneous DBM implementations) |
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233 | |
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234 | Described in L<perltie> and L<AnyDBM_File>. |
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235 | |
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236 | =item * |
237 | |
238 | subroutines can now be overridden, autoloaded, and prototyped |
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239 | |
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240 | Described in L<perlsub>. |
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241 | |
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242 | =item * |
243 | |
244 | arbitrarily nested data structures and anonymous functions |
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245 | |
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246 | Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>. |
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247 | |
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248 | =item * |
249 | |
250 | object-oriented programming |
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251 | |
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252 | Described in L<perlobj>, L<perltoot>, and L<perlbot>. |
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253 | |
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254 | =item * |
255 | |
256 | compilability into C code or Perl bytecode |
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257 | |
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258 | Described in L<B> and L<B::Bytecode>. |
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259 | |
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260 | =item * |
261 | |
262 | support for light-weight processes (threads) |
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263 | |
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264 | Described in L<perlthrtut> and L<Thread>. |
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265 | |
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266 | =item * |
267 | |
268 | support for internationalization, localization, and Unicode |
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269 | |
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270 | Described in L<perllocale> and L<utf8>. |
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271 | |
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272 | =item * |
273 | |
274 | lexical scoping |
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275 | |
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276 | Described in L<perlsub>. |
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277 | |
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278 | =item * |
279 | |
280 | regular expression enhancements |
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281 | |
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282 | Described in L<perlre>, with additional examples in L<perlop>. |
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283 | |
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284 | =item * |
285 | |
286 | enhanced debugger and interactive Perl environment, |
287 | with integrated editor support |
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288 | |
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289 | Described in L<perldebug>. |
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290 | |
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291 | =item * |
292 | |
293 | POSIX 1003.1 compliant library |
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294 | |
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295 | Described in L<POSIX>. |
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296 | |
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297 | =back |
298 | |
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299 | Okay, that's I<definitely> enough hype. |
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300 | |
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301 | =head1 AVAILABILITY |
302 | |
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303 | Perl is available for most operating systems, including virtually |
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304 | all Unix-like platforms. See L<perlport/"Supported Platforms"> |
305 | for a listing. |
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306 | |
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307 | =head1 ENVIRONMENT |
308 | |
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309 | See L<perlrun>. |
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310 | |
311 | =head1 AUTHOR |
312 | |
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313 | Larry Wall <larry@wall.org>, with the help of oodles of other folks. |
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314 | |
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315 | If your Perl success stories and testimonials may be of help to others |
316 | who wish to advocate the use of Perl in their applications, |
317 | or if you wish to simply express your gratitude to Larry and the |
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318 | Perl developers, please write to perl-thanks@perl.org . |
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319 | |
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320 | =head1 FILES |
321 | |
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322 | "@INC" locations of perl libraries |
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323 | |
324 | =head1 SEE ALSO |
325 | |
326 | a2p awk to perl translator |
327 | s2p sed to perl translator |
328 | |
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329 | http://www.perl.com/ the Perl Home Page |
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330 | http://www.perl.com/CPAN the Comprehensive Perl Archive |
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331 | |
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332 | =head1 DIAGNOSTICS |
333 | |
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334 | The C<use warnings> pragma (and the B<-w> switch) produces some |
335 | lovely diagnostics. |
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336 | |
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337 | See L<perldiag> for explanations of all Perl's diagnostics. The C<use |
338 | diagnostics> pragma automatically turns Perl's normally terse warnings |
339 | and errors into these longer forms. |
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340 | |
341 | Compilation errors will tell you the line number of the error, with an |
342 | indication of the next token or token type that was to be examined. |
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343 | (In a script passed to Perl via B<-e> switches, each |
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344 | B<-e> is counted as one line.) |
345 | |
346 | Setuid scripts have additional constraints that can produce error |
347 | messages such as "Insecure dependency". See L<perlsec>. |
348 | |
349 | Did we mention that you should definitely consider using the B<-w> |
350 | switch? |
351 | |
352 | =head1 BUGS |
353 | |
354 | The B<-w> switch is not mandatory. |
355 | |
356 | Perl is at the mercy of your machine's definitions of various |
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357 | operations such as type casting, atof(), and floating-point |
358 | output with sprintf(). |
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359 | |
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360 | If your stdio requires a seek or eof between reads and writes on a |
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361 | particular stream, so does Perl. (This doesn't apply to sysread() |
362 | and syswrite().) |
363 | |
364 | While none of the built-in data types have any arbitrary size limits |
365 | (apart from memory size), there are still a few arbitrary limits: a |
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366 | given variable name may not be longer than 251 characters. Line numbers |
367 | displayed by diagnostics are internally stored as short integers, |
368 | so they are limited to a maximum of 65535 (higher numbers usually being |
369 | affected by wraparound). |
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370 | |
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371 | You may mail your bug reports (be sure to include full configuration |
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372 | information as output by the myconfig program in the perl source |
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373 | tree, or by C<perl -V>) to perlbug@perl.org . If you've succeeded |
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374 | in compiling perl, the B<perlbug> script in the F<utils/> subdirectory |
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375 | can be used to help mail in a bug report. |
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376 | |
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377 | Perl actually stands for Pathologically Eclectic Rubbish Lister, but |
378 | don't tell anyone I said that. |
379 | |
380 | =head1 NOTES |
381 | |
382 | The Perl motto is "There's more than one way to do it." Divining |
383 | how many more is left as an exercise to the reader. |
384 | |
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385 | The three principal virtues of a programmer are Laziness, |
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386 | Impatience, and Hubris. See the Camel Book for why. |
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387 | |