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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 |
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38 | perlunicode Perl unicode support |
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39 | perllocale Perl locale support |
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40 | |
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41 | perlreftut Perl references short introduction |
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42 | perlref Perl references, the rest of the story |
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43 | perldsc Perl data structures intro |
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44 | perllol Perl data structures: arrays of arrays |
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45 | perlboot Perl OO tutorial for beginners |
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46 | perltoot Perl OO tutorial, part 1 |
47 | perltootc Perl OO tutorial, part 2 |
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48 | perlobj Perl objects |
49 | perltie Perl objects hidden behind simple variables |
50 | perlbot Perl OO tricks and examples |
51 | perlipc Perl interprocess communication |
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52 | perlfork Perl fork() information |
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53 | perlthrtut Perl threads tutorial |
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54 | perllexwarn Perl warnings and their control |
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55 | perlfilter Perl source filters |
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56 | perldbmfilter Perl DBM filters |
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57 | |
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58 | perlcompile Perl compiler suite intro |
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59 | perldebug Perl debugging |
60 | perldiag Perl diagnostic messages |
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61 | perlnumber Perl number semantics |
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62 | perlsec Perl security |
63 | perltrap Perl traps for the unwary |
64 | perlport Perl portability guide |
65 | perlstyle Perl style guide |
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66 | |
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67 | perlpod Perl plain old documentation |
68 | perlbook Perl book information |
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69 | |
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70 | perlembed Perl ways to embed perl in your C or C++ application |
71 | perlapio Perl internal IO abstraction interface |
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72 | perldebguts Perl debugging guts and tips |
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73 | perlxs Perl XS application programming interface |
74 | perlxstut Perl XS tutorial |
75 | perlguts Perl internal functions for those doing extensions |
76 | perlcall Perl calling conventions from C |
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77 | perlapi Perl API listing (autogenerated) |
78 | perlintern Perl internal functions (autogenerated) |
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79 | |
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80 | perltodo Perl things to do |
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81 | perlhack Perl hackers guide |
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82 | perlhist Perl history records |
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83 | |
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84 | perlamiga Perl notes for Amiga |
85 | perlcygwin Perl notes for Cygwin |
86 | perldos Perl notes for DOS |
87 | perlhpux Perl notes for HP-UX |
88 | perlos2 Perl notes for OS/2 |
89 | perlos390 Perl notes for OS/390 |
90 | perlvms Perl notes for VMS |
91 | perlwin32 Perl notes for Windows |
92 | |
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93 | (If you're intending to read these straight through for the first time, |
94 | the suggested order will tend to reduce the number of forward references.) |
95 | |
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96 | By default, the manpages listed above are installed in the |
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97 | F</usr/local/man/> directory. |
98 | |
99 | Extensive additional documentation for Perl modules is available. The |
100 | default configuration for perl will place this additional documentation |
101 | in the F</usr/local/lib/perl5/man> directory (or else in the F<man> |
102 | subdirectory of the Perl library directory). Some of this additional |
103 | documentation is distributed standard with Perl, but you'll also find |
104 | documentation for third-party modules there. |
105 | |
106 | You should be able to view Perl's documentation with your man(1) |
107 | program by including the proper directories in the appropriate start-up |
108 | files, or in the MANPATH environment variable. To find out where the |
109 | configuration has installed the manpages, type: |
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110 | |
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111 | perl -V:man.dir |
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112 | |
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113 | If the directories have a common stem, such as F</usr/local/man/man1> |
114 | and F</usr/local/man/man3>, you need only to add that stem |
115 | (F</usr/local/man>) to your man(1) configuration files or your MANPATH |
116 | environment variable. If they do not share a stem, you'll have to add |
117 | both stems. |
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118 | |
119 | If that doesn't work for some reason, you can still use the |
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120 | supplied F<perldoc> script to view module information. You might |
121 | also look into getting a replacement man program. |
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122 | |
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123 | If something strange has gone wrong with your program and you're not |
124 | sure where you should look for help, try the B<-w> switch first. It |
125 | will often point out exactly where the trouble is. |
126 | |
127 | =head1 DESCRIPTION |
128 | |
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129 | Perl is a language optimized for scanning arbitrary |
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130 | text files, extracting information from those text files, and printing |
131 | reports based on that information. It's also a good language for many |
132 | system management tasks. The language is intended to be practical |
133 | (easy to use, efficient, complete) rather than beautiful (tiny, |
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134 | elegant, minimal). |
135 | |
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136 | Perl combines (in the author's opinion, anyway) some of the best |
137 | features of C, B<sed>, B<awk>, and B<sh>, so people familiar with |
138 | those languages should have little difficulty with it. (Language |
139 | historians will also note some vestiges of B<csh>, Pascal, and even |
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140 | BASIC-PLUS.) Expression syntax corresponds closely to C |
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141 | expression syntax. Unlike most Unix utilities, Perl does not |
142 | arbitrarily limit the size of your data--if you've got the memory, |
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143 | Perl can slurp in your whole file as a single string. Recursion is of |
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144 | unlimited depth. And the tables used by hashes (sometimes called |
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145 | "associative arrays") grow as necessary to prevent degraded |
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146 | performance. Perl can use sophisticated pattern matching techniques to |
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147 | scan large amounts of data quickly. Although optimized for |
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148 | scanning text, Perl can also deal with binary data, and can make dbm |
149 | files look like hashes. Setuid Perl scripts are safer than C programs |
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150 | through a dataflow tracing mechanism that prevents many stupid |
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151 | security holes. |
152 | |
153 | If you have a problem that would ordinarily use B<sed> or B<awk> or |
154 | B<sh>, but it exceeds their capabilities or must run a little faster, |
155 | and you don't want to write the silly thing in C, then Perl may be for |
156 | you. There are also translators to turn your B<sed> and B<awk> |
157 | scripts into Perl scripts. |
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158 | |
159 | But wait, there's more... |
160 | |
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161 | Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete |
162 | rewrite that provides the following additional benefits: |
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163 | |
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164 | =over |
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165 | |
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166 | =item * modularity and reusability using innumerable modules |
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167 | |
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168 | Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>. |
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169 | |
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170 | =item * embeddable and extensible |
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171 | |
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172 | Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>, |
173 | L<perlguts>, and L<xsubpp>. |
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174 | |
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175 | =item * roll-your-own magic variables (including multiple simultaneous DBM implementations) |
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176 | |
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177 | Described in L<perltie> and L<AnyDBM_File>. |
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178 | |
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179 | =item * subroutines can now be overridden, autoloaded, and prototyped |
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180 | |
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181 | Described in L<perlsub>. |
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182 | |
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183 | =item * arbitrarily nested data structures and anonymous functions |
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184 | |
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185 | Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>. |
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186 | |
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187 | =item * object-oriented programming |
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188 | |
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189 | Described in L<perlobj>, L<perltoot>, and L<perlbot>. |
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190 | |
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191 | =item * compilability into C code or Perl bytecode |
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192 | |
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193 | Described in L<B> and L<B::Bytecode>. |
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194 | |
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195 | =item * support for light-weight processes (threads) |
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196 | |
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197 | Described in L<perlthrtut> and L<Thread>. |
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198 | |
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199 | =item * support for internationalization, localization, and Unicode |
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200 | |
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201 | Described in L<perllocale> and L<utf8>. |
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202 | |
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203 | =item * lexical scoping |
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204 | |
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205 | Described in L<perlsub>. |
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206 | |
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207 | =item * regular expression enhancements |
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208 | |
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209 | Described in L<perlre>, with additional examples in L<perlop>. |
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210 | |
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211 | =item * enhanced debugger and interactive Perl environment, with integrated editor support |
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212 | |
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213 | Described in L<perldebug>. |
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214 | |
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215 | =item * POSIX 1003.1 compliant library |
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216 | |
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217 | Described in L<POSIX>. |
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218 | |
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219 | =back |
220 | |
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221 | Okay, that's I<definitely> enough hype. |
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222 | |
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223 | =head1 AVAILABILITY |
224 | |
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225 | Perl is available for most operating systems, including virtually |
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226 | all Unix-like platforms. See L<perlport/"Supported Platforms"> |
227 | for a listing. |
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228 | |
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229 | =head1 ENVIRONMENT |
230 | |
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231 | See L<perlrun>. |
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232 | |
233 | =head1 AUTHOR |
234 | |
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235 | Larry Wall <larry@wall.org>, with the help of oodles of other folks. |
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236 | |
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237 | If your Perl success stories and testimonials may be of help to others |
238 | who wish to advocate the use of Perl in their applications, |
239 | or if you wish to simply express your gratitude to Larry and the |
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240 | Perl developers, please write to perl-thanks@perl.org . |
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241 | |
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242 | =head1 FILES |
243 | |
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244 | "@INC" locations of perl libraries |
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245 | |
246 | =head1 SEE ALSO |
247 | |
248 | a2p awk to perl translator |
249 | s2p sed to perl translator |
250 | |
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251 | http://www.perl.com/ the Perl Home Page |
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252 | http://www.perl.com/CPAN the Comprehensive Perl Archive |
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253 | |
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254 | =head1 DIAGNOSTICS |
255 | |
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256 | The C<use warnings> pragma (and the B<-w> switch) produces some |
257 | lovely diagnostics. |
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258 | |
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259 | See L<perldiag> for explanations of all Perl's diagnostics. The C<use |
260 | diagnostics> pragma automatically turns Perl's normally terse warnings |
261 | and errors into these longer forms. |
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262 | |
263 | Compilation errors will tell you the line number of the error, with an |
264 | indication of the next token or token type that was to be examined. |
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265 | (In a script passed to Perl via B<-e> switches, each |
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266 | B<-e> is counted as one line.) |
267 | |
268 | Setuid scripts have additional constraints that can produce error |
269 | messages such as "Insecure dependency". See L<perlsec>. |
270 | |
271 | Did we mention that you should definitely consider using the B<-w> |
272 | switch? |
273 | |
274 | =head1 BUGS |
275 | |
276 | The B<-w> switch is not mandatory. |
277 | |
278 | Perl is at the mercy of your machine's definitions of various |
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279 | operations such as type casting, atof(), and floating-point |
280 | output with sprintf(). |
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281 | |
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282 | If your stdio requires a seek or eof between reads and writes on a |
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283 | particular stream, so does Perl. (This doesn't apply to sysread() |
284 | and syswrite().) |
285 | |
286 | While none of the built-in data types have any arbitrary size limits |
287 | (apart from memory size), there are still a few arbitrary limits: a |
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288 | given variable name may not be longer than 251 characters. Line numbers |
289 | displayed by diagnostics are internally stored as short integers, |
290 | so they are limited to a maximum of 65535 (higher numbers usually being |
291 | affected by wraparound). |
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292 | |
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293 | You may mail your bug reports (be sure to include full configuration |
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294 | information as output by the myconfig program in the perl source |
295 | tree, or by C<perl -V>) to perlbug@perl.com . If you've succeeded |
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296 | in compiling perl, the B<perlbug> script in the F<utils/> subdirectory |
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297 | can be used to help mail in a bug report. |
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298 | |
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299 | Perl actually stands for Pathologically Eclectic Rubbish Lister, but |
300 | don't tell anyone I said that. |
301 | |
302 | =head1 NOTES |
303 | |
304 | The Perl motto is "There's more than one way to do it." Divining |
305 | how many more is left as an exercise to the reader. |
306 | |
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307 | The three principal virtues of a programmer are Laziness, |
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308 | Impatience, and Hubris. See the Camel Book for why. |
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309 | |