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