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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 | perlcompile Perl compiler suite intro |
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54 | perldebug Perl debugging |
55 | perldiag Perl diagnostic messages |
56 | perlsec Perl security |
57 | perltrap Perl traps for the unwary |
58 | perlport Perl portability guide |
59 | perlstyle Perl style guide |
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60 | |
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61 | perlpod Perl plain old documentation |
62 | perlbook Perl book information |
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63 | |
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64 | perlembed Perl ways to embed perl in your C or C++ application |
65 | perlapio Perl internal IO abstraction interface |
66 | perlxs Perl XS application programming interface |
67 | perlxstut Perl XS tutorial |
68 | perlguts Perl internal functions for those doing extensions |
69 | perlcall Perl calling conventions from C |
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70 | |
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71 | perltodo Perl things to do |
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72 | perlhack Perl hackers guide |
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73 | perlhist Perl history records |
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74 | |
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75 | (If you're intending to read these straight through for the first time, |
76 | the suggested order will tend to reduce the number of forward references.) |
77 | |
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78 | By default, the manpages listed above are installed in the |
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79 | F</usr/local/man/> directory. |
80 | |
81 | Extensive additional documentation for Perl modules is available. The |
82 | default configuration for perl will place this additional documentation |
83 | in the F</usr/local/lib/perl5/man> directory (or else in the F<man> |
84 | subdirectory of the Perl library directory). Some of this additional |
85 | documentation is distributed standard with Perl, but you'll also find |
86 | documentation for third-party modules there. |
87 | |
88 | You should be able to view Perl's documentation with your man(1) |
89 | program by including the proper directories in the appropriate start-up |
90 | files, or in the MANPATH environment variable. To find out where the |
91 | configuration has installed the manpages, type: |
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92 | |
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93 | perl -V:man.dir |
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94 | |
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95 | If the directories have a common stem, such as F</usr/local/man/man1> |
96 | and F</usr/local/man/man3>, you need only to add that stem |
97 | (F</usr/local/man>) to your man(1) configuration files or your MANPATH |
98 | environment variable. If they do not share a stem, you'll have to add |
99 | both stems. |
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100 | |
101 | If that doesn't work for some reason, you can still use the |
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102 | supplied F<perldoc> script to view module information. You might |
103 | also look into getting a replacement man program. |
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104 | |
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105 | If something strange has gone wrong with your program and you're not |
106 | sure where you should look for help, try the B<-w> switch first. It |
107 | will often point out exactly where the trouble is. |
108 | |
109 | =head1 DESCRIPTION |
110 | |
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111 | Perl is a language optimized for scanning arbitrary |
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112 | text files, extracting information from those text files, and printing |
113 | reports based on that information. It's also a good language for many |
114 | system management tasks. The language is intended to be practical |
115 | (easy to use, efficient, complete) rather than beautiful (tiny, |
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116 | elegant, minimal). |
117 | |
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118 | Perl combines (in the author's opinion, anyway) some of the best |
119 | features of C, B<sed>, B<awk>, and B<sh>, so people familiar with |
120 | those languages should have little difficulty with it. (Language |
121 | historians will also note some vestiges of B<csh>, Pascal, and even |
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122 | BASIC-PLUS.) Expression syntax corresponds closely to C |
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123 | expression syntax. Unlike most Unix utilities, Perl does not |
124 | arbitrarily limit the size of your data--if you've got the memory, |
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125 | Perl can slurp in your whole file as a single string. Recursion is of |
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126 | unlimited depth. And the tables used by hashes (sometimes called |
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127 | "associative arrays") grow as necessary to prevent degraded |
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128 | performance. Perl can use sophisticated pattern matching techniques to |
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129 | scan large amounts of data quickly. Although optimized for |
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130 | scanning text, Perl can also deal with binary data, and can make dbm |
131 | files look like hashes. Setuid Perl scripts are safer than C programs |
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132 | through a dataflow tracing mechanism that prevents many stupid |
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133 | security holes. |
134 | |
135 | If you have a problem that would ordinarily use B<sed> or B<awk> or |
136 | B<sh>, but it exceeds their capabilities or must run a little faster, |
137 | and you don't want to write the silly thing in C, then Perl may be for |
138 | you. There are also translators to turn your B<sed> and B<awk> |
139 | scripts into Perl scripts. |
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140 | |
141 | But wait, there's more... |
142 | |
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143 | Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete |
144 | rewrite that provides the following additional benefits: |
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145 | |
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146 | =over |
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147 | |
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148 | =item * modularity and reusability using innumerable modules |
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149 | |
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150 | Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>. |
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151 | |
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152 | =item * embeddable and extensible |
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153 | |
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154 | Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>, |
155 | L<perlguts>, and L<xsubpp>. |
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156 | |
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157 | =item * roll-your-own magic variables (including multiple simultaneous DBM implementations) |
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158 | |
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159 | Described in L<perltie> and L<AnyDBM_File>. |
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160 | |
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161 | =item * subroutines can now be overridden, autoloaded, and prototyped |
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162 | |
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163 | Described in L<perlsub>. |
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164 | |
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165 | =item * arbitrarily nested data structures and anonymous functions |
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166 | |
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167 | Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>. |
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168 | |
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169 | =item * object-oriented programming |
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170 | |
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171 | Described in L<perlobj>, L<perltoot>, and L<perlbot>. |
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172 | |
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173 | =item * compilability into C code or Perl bytecode |
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174 | |
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175 | Described in L<B> and L<B::Bytecode>. |
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176 | |
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177 | =item * support for light-weight processes (threads) |
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178 | |
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179 | Described in L<perlthrtut> and L<Thread>. |
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180 | |
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181 | =item * support for internationalization, localization, and Unicode |
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182 | |
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183 | Described in L<perllocale> and L<utf8>. |
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184 | |
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185 | =item * lexical scoping |
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186 | |
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187 | Described in L<perlsub>. |
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188 | |
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189 | =item * regular expression enhancements |
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190 | |
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191 | Described in L<perlre>, with additional examples in L<perlop>. |
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192 | |
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193 | =item * enhanced debugger and interactive Perl environment, with integrated editor support |
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194 | |
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195 | Described in L<perldebug>. |
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196 | |
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197 | =item * POSIX 1003.1 compliant library |
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198 | |
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199 | Described in L<POSIX>. |
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200 | |
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201 | =back |
202 | |
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203 | Okay, that's I<definitely> enough hype. |
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204 | |
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205 | =head1 AVAILABILITY |
206 | |
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207 | Perl is available for most operating systems, including virtually |
208 | all Unix-like platforms. |
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209 | |
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210 | As of May 1999, the following platforms are able to build Perl |
211 | from the standard source code distribution available at |
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212 | http://www.perl.com/CPAN/src/index.html |
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213 | |
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214 | AIX Linux SCO ODT/OSR |
215 | A/UX MachTen Solaris |
216 | BeOS MPE/iX SunOS |
217 | BSD/OS NetBSD SVR4 |
218 | DG/UX NextSTEP Tru64 UNIX 3) |
219 | DomainOS OpenBSD Ultrix |
220 | DOS DJGPP 1) OpenSTEP UNICOS |
221 | DYNIX/ptx OS/2 VMS |
222 | FreeBSD OS390 2) VOS |
223 | HP-UX PowerMAX Windows 3.1 1) |
224 | Hurd QNX Windows 95 1) 4) |
225 | IRIX Windows 98 1) 4) |
226 | Windows NT 1) 4) |
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227 | |
228 | 1) in DOS mode either the DOS or OS/2 ports can be used |
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229 | 2) formerly known as MVS |
230 | 3) formerly known as Digital UNIX and before that DEC OSF/1 |
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231 | 4) compilers: Borland, Cygwin, Mingw32 EGCS/GCC, VC++ |
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232 | |
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233 | The following platforms have been known to build Perl from source, |
234 | but we haven't been able to verify their status for the current release, |
235 | either because the hardware/software platforms are rare or |
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236 | because we don't have an active champion on these platforms--or both. |
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237 | |
238 | 3b1 FPS Plan 9 |
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239 | AmigaOS GENIX PowerUX |
240 | ConvexOS Greenhills RISC/os |
241 | CX/UX ISC Stellar |
242 | DC/OSx MachTen 68k SVR2 |
243 | DDE SMES MiNT TI1500 |
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244 | DOS EMX MPC TitanOS |
245 | Dynix NEWS-OS UNICOS/mk |
246 | EP/IX Opus Unisys Dynix |
247 | ESIX Unixware |
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248 | |
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249 | Support for the following platforms is planned for the next major |
250 | Perl release. |
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251 | |
252 | BS2000 |
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253 | Netware |
254 | Rhapsody |
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255 | VM/ESA |
256 | |
257 | The following platforms have their own source code distributions and |
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258 | binaries available via http://www.perl.com/CPAN/ports/index.html. |
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259 | |
260 | Perl release |
261 | |
262 | AS/400 5.003 |
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263 | MacOS 5.004 |
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264 | Netware 5.003_07 |
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265 | Tandem Guardian 5.004 |
266 | |
267 | The following platforms have only binaries available via |
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268 | http://www.perl.com/CPAN/ports/index.html. |
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269 | |
270 | Perl release |
271 | |
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272 | Acorn RISCOS 5.005_02 |
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273 | AOS 5.002 |
274 | LynxOS 5.004_02 |
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275 | |
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276 | =head1 ENVIRONMENT |
277 | |
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278 | See L<perlrun>. |
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279 | |
280 | =head1 AUTHOR |
281 | |
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282 | Larry Wall <larry@wall.org>, with the help of oodles of other folks. |
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283 | |
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284 | If your Perl success stories and testimonials may be of help to others |
285 | who wish to advocate the use of Perl in their applications, |
286 | or if you wish to simply express your gratitude to Larry and the |
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287 | Perl developers, please write to perl-thanks@perl.org . |
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288 | |
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289 | =head1 FILES |
290 | |
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291 | "@INC" locations of perl libraries |
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292 | |
293 | =head1 SEE ALSO |
294 | |
295 | a2p awk to perl translator |
296 | s2p sed to perl translator |
297 | |
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298 | http://www.perl.com/ the Perl Home Page |
299 | http://www.perl.com/CPAN the Comphrehensive Perl Archive |
300 | |
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301 | =head1 DIAGNOSTICS |
302 | |
303 | The B<-w> switch produces some lovely diagnostics. |
304 | |
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305 | See L<perldiag> for explanations of all Perl's diagnostics. The C<use |
306 | diagnostics> pragma automatically turns Perl's normally terse warnings |
307 | and errors into these longer forms. |
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308 | |
309 | Compilation errors will tell you the line number of the error, with an |
310 | indication of the next token or token type that was to be examined. |
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311 | (In a script passed to Perl via B<-e> switches, each |
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312 | B<-e> is counted as one line.) |
313 | |
314 | Setuid scripts have additional constraints that can produce error |
315 | messages such as "Insecure dependency". See L<perlsec>. |
316 | |
317 | Did we mention that you should definitely consider using the B<-w> |
318 | switch? |
319 | |
320 | =head1 BUGS |
321 | |
322 | The B<-w> switch is not mandatory. |
323 | |
324 | Perl is at the mercy of your machine's definitions of various |
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325 | operations such as type casting, atof(), and floating-point |
326 | output with sprintf(). |
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327 | |
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328 | If your stdio requires a seek or eof between reads and writes on a |
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329 | particular stream, so does Perl. (This doesn't apply to sysread() |
330 | and syswrite().) |
331 | |
332 | While none of the built-in data types have any arbitrary size limits |
333 | (apart from memory size), there are still a few arbitrary limits: a |
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334 | given variable name may not be longer than 251 characters. Line numbers |
335 | displayed by diagnostics are internally stored as short integers, |
336 | so they are limited to a maximum of 65535 (higher numbers usually being |
337 | affected by wraparound). |
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338 | |
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339 | You may mail your bug reports (be sure to include full configuration |
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340 | information as output by the myconfig program in the perl source |
341 | tree, or by C<perl -V>) to perlbug@perl.com . If you've succeeded |
342 | in compiling perl, the perlbug script in the utils/ subdirectory |
343 | can be used to help mail in a bug report. |
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344 | |
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345 | Perl actually stands for Pathologically Eclectic Rubbish Lister, but |
346 | don't tell anyone I said that. |
347 | |
348 | =head1 NOTES |
349 | |
350 | The Perl motto is "There's more than one way to do it." Divining |
351 | how many more is left as an exercise to the reader. |
352 | |
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353 | The three principal virtues of a programmer are Laziness, |
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354 | Impatience, and Hubris. See the Camel Book for why. |
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355 | |