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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 |
72 | perlxs Perl XS application programming interface |
73 | perlxstut Perl XS tutorial |
74 | perlguts Perl internal functions for those doing extensions |
75 | perlcall Perl calling conventions from C |
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76 | perlapi Perl API listing (autogenerated) |
77 | perlintern Perl internal functions (autogenerated) |
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78 | |
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79 | perltodo Perl things to do |
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80 | perlhack Perl hackers guide |
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81 | perlhist Perl history records |
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82 | |
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83 | perlamiga Perl notes for Amiga |
84 | perlcygwin Perl notes for Cygwin |
85 | perldos Perl notes for DOS |
86 | perlhpux Perl notes for HP-UX |
87 | perlos2 Perl notes for OS/2 |
88 | perlos390 Perl notes for OS/390 |
89 | perlvms Perl notes for VMS |
90 | perlwin32 Perl notes for Windows |
91 | |
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92 | (If you're intending to read these straight through for the first time, |
93 | the suggested order will tend to reduce the number of forward references.) |
94 | |
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95 | By default, the manpages listed above are installed in the |
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96 | F</usr/local/man/> directory. |
97 | |
98 | Extensive additional documentation for Perl modules is available. The |
99 | default configuration for perl will place this additional documentation |
100 | in the F</usr/local/lib/perl5/man> directory (or else in the F<man> |
101 | subdirectory of the Perl library directory). Some of this additional |
102 | documentation is distributed standard with Perl, but you'll also find |
103 | documentation for third-party modules there. |
104 | |
105 | You should be able to view Perl's documentation with your man(1) |
106 | program by including the proper directories in the appropriate start-up |
107 | files, or in the MANPATH environment variable. To find out where the |
108 | configuration has installed the manpages, type: |
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109 | |
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110 | perl -V:man.dir |
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111 | |
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112 | If the directories have a common stem, such as F</usr/local/man/man1> |
113 | and F</usr/local/man/man3>, you need only to add that stem |
114 | (F</usr/local/man>) to your man(1) configuration files or your MANPATH |
115 | environment variable. If they do not share a stem, you'll have to add |
116 | both stems. |
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117 | |
118 | If that doesn't work for some reason, you can still use the |
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119 | supplied F<perldoc> script to view module information. You might |
120 | also look into getting a replacement man program. |
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121 | |
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122 | If something strange has gone wrong with your program and you're not |
123 | sure where you should look for help, try the B<-w> switch first. It |
124 | will often point out exactly where the trouble is. |
125 | |
126 | =head1 DESCRIPTION |
127 | |
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128 | Perl is a language optimized for scanning arbitrary |
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129 | text files, extracting information from those text files, and printing |
130 | reports based on that information. It's also a good language for many |
131 | system management tasks. The language is intended to be practical |
132 | (easy to use, efficient, complete) rather than beautiful (tiny, |
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133 | elegant, minimal). |
134 | |
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135 | Perl combines (in the author's opinion, anyway) some of the best |
136 | features of C, B<sed>, B<awk>, and B<sh>, so people familiar with |
137 | those languages should have little difficulty with it. (Language |
138 | historians will also note some vestiges of B<csh>, Pascal, and even |
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139 | BASIC-PLUS.) Expression syntax corresponds closely to C |
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140 | expression syntax. Unlike most Unix utilities, Perl does not |
141 | arbitrarily limit the size of your data--if you've got the memory, |
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142 | Perl can slurp in your whole file as a single string. Recursion is of |
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143 | unlimited depth. And the tables used by hashes (sometimes called |
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144 | "associative arrays") grow as necessary to prevent degraded |
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145 | performance. Perl can use sophisticated pattern matching techniques to |
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146 | scan large amounts of data quickly. Although optimized for |
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147 | scanning text, Perl can also deal with binary data, and can make dbm |
148 | files look like hashes. Setuid Perl scripts are safer than C programs |
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149 | through a dataflow tracing mechanism that prevents many stupid |
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150 | security holes. |
151 | |
152 | If you have a problem that would ordinarily use B<sed> or B<awk> or |
153 | B<sh>, but it exceeds their capabilities or must run a little faster, |
154 | and you don't want to write the silly thing in C, then Perl may be for |
155 | you. There are also translators to turn your B<sed> and B<awk> |
156 | scripts into Perl scripts. |
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157 | |
158 | But wait, there's more... |
159 | |
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160 | Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete |
161 | rewrite that provides the following additional benefits: |
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162 | |
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163 | =over |
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164 | |
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165 | =item * modularity and reusability using innumerable modules |
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166 | |
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167 | Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>. |
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168 | |
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169 | =item * embeddable and extensible |
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170 | |
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171 | Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>, |
172 | L<perlguts>, and L<xsubpp>. |
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173 | |
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174 | =item * roll-your-own magic variables (including multiple simultaneous DBM implementations) |
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175 | |
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176 | Described in L<perltie> and L<AnyDBM_File>. |
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177 | |
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178 | =item * subroutines can now be overridden, autoloaded, and prototyped |
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179 | |
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180 | Described in L<perlsub>. |
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181 | |
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182 | =item * arbitrarily nested data structures and anonymous functions |
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183 | |
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184 | Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>. |
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185 | |
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186 | =item * object-oriented programming |
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187 | |
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188 | Described in L<perlobj>, L<perltoot>, and L<perlbot>. |
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189 | |
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190 | =item * compilability into C code or Perl bytecode |
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191 | |
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192 | Described in L<B> and L<B::Bytecode>. |
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193 | |
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194 | =item * support for light-weight processes (threads) |
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195 | |
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196 | Described in L<perlthrtut> and L<Thread>. |
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197 | |
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198 | =item * support for internationalization, localization, and Unicode |
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199 | |
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200 | Described in L<perllocale> and L<utf8>. |
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201 | |
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202 | =item * lexical scoping |
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203 | |
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204 | Described in L<perlsub>. |
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205 | |
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206 | =item * regular expression enhancements |
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207 | |
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208 | Described in L<perlre>, with additional examples in L<perlop>. |
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209 | |
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210 | =item * enhanced debugger and interactive Perl environment, with integrated editor support |
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211 | |
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212 | Described in L<perldebug>. |
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213 | |
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214 | =item * POSIX 1003.1 compliant library |
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215 | |
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216 | Described in L<POSIX>. |
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217 | |
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218 | =back |
219 | |
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220 | Okay, that's I<definitely> enough hype. |
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221 | |
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222 | =head1 AVAILABILITY |
223 | |
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224 | Perl is available for most operating systems, including virtually |
225 | all Unix-like platforms. |
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226 | |
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227 | As of early March 2000 (the Perl release 5.6.0), the following |
228 | platforms are able to build Perl from the standard source code |
229 | distribution available at http://www.perl.com/CPAN/src/index.html |
230 | |
231 | AIX |
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232 | DOS DJGPP 1) |
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233 | FreeBSD |
234 | HP-UX |
235 | IRIX |
236 | Linux |
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237 | LynxOS |
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238 | MachTen |
239 | MPE/iX |
240 | NetBSD |
241 | OpenBSD |
242 | OS/2 |
243 | Rhapsody/Darwin 2) |
244 | Solaris |
245 | Tru64 UNIX 3) |
246 | UNICOS |
247 | UNICOS/mk |
248 | VMS |
249 | VOS |
250 | Windows 3.1 1) |
251 | Windows 95 1) 4) |
252 | Windows 98 1) 4) |
253 | Windows NT 1) 4) |
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254 | |
255 | 1) in DOS mode either the DOS or OS/2 ports can be used |
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256 | 2) new in 5.6.0: the BSD/NeXT-based UNIX of Mac OS X |
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257 | 3) formerly known as Digital UNIX and before that DEC OSF/1 |
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258 | 4) compilers: Borland, Cygwin, Mingw32 EGCS/GCC, VC++ |
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259 | |
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260 | The following platforms worked for the previous major release |
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261 | (5.005_03 being the latest maintenance release of that, as of early |
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262 | March 2000), but be did not manage to test these in time for the 5.6.0 |
263 | release of Perl. There is a very good chance that these will work |
264 | just fine with 5.6.0. |
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265 | |
266 | A/UX |
267 | BeOS |
268 | BSD/OS |
269 | DG/UX |
270 | DYNIX/ptx |
271 | DomainOS |
272 | Hurd |
273 | NextSTEP |
274 | OpenSTEP |
275 | PowerMAX |
276 | QNX |
277 | SCO ODT/OSR |
278 | SunOS |
279 | SVR4 |
280 | Ultrix |
281 | |
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282 | The following platform worked for the previous major release (5.005_03 |
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283 | being the latest maintenance release of that, as of early March 2000). |
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284 | However, standardization on UTF-8 as the internal string representation |
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285 | in 5.6.0 has introduced incompatibilities in this EBCDIC platform. |
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286 | Support for this platform may be enabled in a future release: |
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287 | |
288 | OS390 1) |
289 | |
290 | 1) Previously known as MVS, or OpenEdition MVS. |
291 | |
292 | Strongly related to the OS390 platform by also being EBCDIC-based |
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293 | mainframe platforms are the following platforms: |
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294 | |
295 | BS2000 |
296 | VM/ESA |
297 | |
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298 | These are also not expected to work under 5.6.0 for the same reasons |
299 | as OS390. Contact the mailing list perl-mvs@perl.org for more details. |
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300 | |
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301 | MacOS (Classic, pre-X) is almost 5.6.0-ready; building from the source |
302 | does work with 5.6.0, but additional MacOS specific source code is needed |
303 | for a complete port. Contact the mailing list macperl-porters@macperl.org |
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304 | for more more information. |
305 | |
306 | The following platforms have been known to build Perl from source in |
307 | the past, but we haven't been able to verify their status for the |
308 | current release, either because the hardware/software platforms are |
309 | rare or because we don't have an active champion on these |
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310 | platforms--or both: |
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311 | |
312 | 3b1 |
313 | AmigaOS |
314 | ConvexOS |
315 | CX/UX |
316 | DC/OSx |
317 | DDE SMES |
318 | DOS EMX |
319 | Dynix |
320 | EP/IX |
321 | ESIX |
322 | FPS |
323 | GENIX |
324 | Greenhills |
325 | ISC |
326 | MachTen 68k |
327 | MiNT |
328 | MPC |
329 | NEWS-OS |
330 | Opus |
331 | Plan 9 |
332 | PowerUX |
333 | RISC/os |
334 | Stellar |
335 | SVR2 |
336 | TI1500 |
337 | TitanOS |
338 | Unisys Dynix |
339 | Unixware |
340 | |
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341 | Support for the following platform is planned for a future Perl release: |
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342 | |
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343 | Netware |
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344 | |
345 | The following platforms have their own source code distributions and |
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346 | binaries available via http://www.perl.com/CPAN/ports/index.html: |
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347 | |
348 | Perl release |
349 | |
350 | AS/400 5.003 |
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351 | Netware 5.003_07 |
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352 | Tandem Guardian 5.004 |
353 | |
354 | The following platforms have only binaries available via |
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355 | http://www.perl.com/CPAN/ports/index.html: |
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356 | |
357 | Perl release |
358 | |
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359 | Acorn RISCOS 5.005_02 |
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360 | AOS 5.002 |
361 | LynxOS 5.004_02 |
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362 | |
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363 | Although we do suggest that you always build your own Perl from |
364 | the source code, both for maximal configurability and for security, |
365 | in case you are in a hurry you can check |
366 | http://www.perl.com/CPAN/ports/index.html for binary distributions. |
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367 | |
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368 | =head1 ENVIRONMENT |
369 | |
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370 | See L<perlrun>. |
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371 | |
372 | =head1 AUTHOR |
373 | |
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374 | Larry Wall <larry@wall.org>, with the help of oodles of other folks. |
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375 | |
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376 | If your Perl success stories and testimonials may be of help to others |
377 | who wish to advocate the use of Perl in their applications, |
378 | or if you wish to simply express your gratitude to Larry and the |
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379 | Perl developers, please write to perl-thanks@perl.org . |
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380 | |
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381 | =head1 FILES |
382 | |
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383 | "@INC" locations of perl libraries |
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384 | |
385 | =head1 SEE ALSO |
386 | |
387 | a2p awk to perl translator |
388 | s2p sed to perl translator |
389 | |
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390 | http://www.perl.com/ the Perl Home Page |
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391 | http://www.perl.com/CPAN the Comprehensive Perl Archive |
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392 | |
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393 | =head1 DIAGNOSTICS |
394 | |
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395 | The C<use warnings> pragma (and the B<-w> switch) produces some |
396 | lovely diagnostics. |
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397 | |
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398 | See L<perldiag> for explanations of all Perl's diagnostics. The C<use |
399 | diagnostics> pragma automatically turns Perl's normally terse warnings |
400 | and errors into these longer forms. |
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401 | |
402 | Compilation errors will tell you the line number of the error, with an |
403 | indication of the next token or token type that was to be examined. |
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404 | (In a script passed to Perl via B<-e> switches, each |
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405 | B<-e> is counted as one line.) |
406 | |
407 | Setuid scripts have additional constraints that can produce error |
408 | messages such as "Insecure dependency". See L<perlsec>. |
409 | |
410 | Did we mention that you should definitely consider using the B<-w> |
411 | switch? |
412 | |
413 | =head1 BUGS |
414 | |
415 | The B<-w> switch is not mandatory. |
416 | |
417 | Perl is at the mercy of your machine's definitions of various |
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418 | operations such as type casting, atof(), and floating-point |
419 | output with sprintf(). |
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420 | |
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421 | If your stdio requires a seek or eof between reads and writes on a |
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422 | particular stream, so does Perl. (This doesn't apply to sysread() |
423 | and syswrite().) |
424 | |
425 | While none of the built-in data types have any arbitrary size limits |
426 | (apart from memory size), there are still a few arbitrary limits: a |
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427 | given variable name may not be longer than 251 characters. Line numbers |
428 | displayed by diagnostics are internally stored as short integers, |
429 | so they are limited to a maximum of 65535 (higher numbers usually being |
430 | affected by wraparound). |
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431 | |
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432 | You may mail your bug reports (be sure to include full configuration |
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433 | information as output by the myconfig program in the perl source |
434 | tree, or by C<perl -V>) to perlbug@perl.com . If you've succeeded |
435 | in compiling perl, the perlbug script in the utils/ subdirectory |
436 | can be used to help mail in a bug report. |
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437 | |
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438 | Perl actually stands for Pathologically Eclectic Rubbish Lister, but |
439 | don't tell anyone I said that. |
440 | |
441 | =head1 NOTES |
442 | |
443 | The Perl motto is "There's more than one way to do it." Divining |
444 | how many more is left as an exercise to the reader. |
445 | |
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446 | The three principal virtues of a programmer are Laziness, |
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447 | Impatience, and Hubris. See the Camel Book for why. |
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448 | |