X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperl.pod;h=dc977645d6dd0a4f67d42832d9e8f3f3c2a95b88;hb=1d7c184104c076988718a01b77c8706aae05b092;hp=302f58b94df27d6a85d870af32d21ec83704ac58;hpb=aa6893958c2bfb6fa4ab923c8466c188c65748fd;p=p5sagit%2Fp5-mst-13.2.git diff --git a/pod/perl.pod b/pod/perl.pod index 302f58b..dc97764 100644 --- a/pod/perl.pod +++ b/pod/perl.pod @@ -4,74 +4,100 @@ perl - Practical Extraction and Report Language =head1 SYNOPSIS -B S<[ B<-sTuU> ]> - S<[ B<-hv> ] [ B<-V>[:I] ]> - S<[ B<-cw> ] [ B<-d>[:I] ] [ B<-D>[I] ]> - S<[ B<-pna> ] [ B<-F>I ] [ B<-l>[I] ] [ B<-0>[I] ]> - S<[ B<-I>I ] [ B<-m>[B<->]I ] [ B<-M>[B<->]I<'module...'> ]> - S<[ B<-P> ]> - S<[ B<-S> ]> - S<[ B<-x>[I] ]> - S<[ B<-i>[I] ]> - S<[ B<-e> I<'command'> ] [ B<--> ] [ I ] [ I ]...> - -For ease of access, the Perl manual has been split up into a number -of sections: - - perl Perl overview (this section) - perldelta Perl changes since previous version - - perldata Perl data structures - perlsyn Perl syntax - perlop Perl operators and precedence - perlre Perl regular expressions - perlrun Perl execution and options - perlfunc Perl builtin functions - perlvar Perl predefined variables - perlsub Perl subroutines - perlmod Perl modules - perlform Perl formats - perllocale Perl locale support - - perlref Perl references - perldsc Perl data structures intro - perllol Perl data structures: lists of lists - perltoot Perl OO tutorial - perlobj Perl objects - perltie Perl objects hidden behind simple variables - perlbot Perl OO tricks and examples - perlipc Perl interprocess communication - - perldebug Perl debugging - perldiag Perl diagnostic messages - perlsec Perl security - perltrap Perl traps for the unwary - perlstyle Perl style guide - - perlpod Perl plain old documentation - perlbook Perl book information - - perlembed Perl how to embed perl in your C or C++ app - perlapio Perl internal IO abstraction interface - perlxs Perl XS application programming interface - perlxstut Perl XS tutorial - perlguts Perl internal functions for those doing extensions - perlcall Perl calling conventions from C +B S<[ B<-sTuU> ]> S<[ B<-hv> ] [ B<-V>[:I] ]> + S<[ B<-cw> ] [ B<-d>[:I] ] [ B<-D>[I] ]> + S<[ B<-pna> ] [ B<-F>I ] [ B<-l>[I] ] [ B<-0>[I] ]> + S<[ B<-I>I ] [ B<-m>[B<->]I ] [ B<-M>[B<->]I<'module...'> ]> + S<[ B<-P> ]> S<[ B<-S> ]> S<[ B<-x>[I] ]> + S<[ B<-i>[I] ]> S<[ B<-e> I<'command'> ] + [ B<--> ] [ I ] [ I ]...> + +For ease of access, the Perl manual has been split up into several +sections: + + perl Perl overview (this section) + perldelta Perl changes since previous version + perl5005delta Perl changes in version 5.005 + perl5004delta Perl changes in version 5.004 + perlfaq Perl frequently asked questions + perltoc Perl documentation table of contents + + perldata Perl data structures + perlsyn Perl syntax + perlop Perl operators and precedence + perlre Perl regular expressions + perlrun Perl execution and options + perlfunc Perl builtin functions + perlopentut Perl open() tutorial + perlvar Perl predefined variables + perlsub Perl subroutines + perlmod Perl modules: how they work + perlmodlib Perl modules: how to write and use + perlmodinstall Perl modules: how to install from CPAN + perlform Perl formats + perllocale Perl locale support + + perlreftut Perl references short introduction + perlref Perl references, the rest of the story + perldsc Perl data structures intro + perllol Perl data structures: arrays of arrays + perltoot Perl OO tutorial, part 1 + perltootc Perl OO tutorial, part 2 + perlobj Perl objects + perltie Perl objects hidden behind simple variables + perlbot Perl OO tricks and examples + perlipc Perl interprocess communication + perlfork Perl fork() information + perlthrtut Perl threads tutorial + perldbmfilter Perl DBM Filters + + perlcompile Perl compiler suite intro + perldebug Perl debugging + perldiag Perl diagnostic messages + perlsec Perl security + perltrap Perl traps for the unwary + perlport Perl portability guide + perlstyle Perl style guide + + perlpod Perl plain old documentation + perlbook Perl book information + + perlembed Perl ways to embed perl in your C or C++ application + perlapio Perl internal IO abstraction interface + perlxs Perl XS application programming interface + perlxstut Perl XS tutorial + perlguts Perl internal functions for those doing extensions + perlcall Perl calling conventions from C + + perltodo Perl things to do + perlhack Perl hackers guide + perlhist Perl history records (If you're intending to read these straight through for the first time, the suggested order will tend to reduce the number of forward references.) -Additional documentation for Perl modules is available in the -F directory. Some of this is distributed standard with -Perl, but you'll also find third-party modules there. You should be able -to view this with your man(1) program by including the proper directories -in the appropriate start-up files. To find out where these are, type: +By default, the manpages listed above are installed in the +F directory. + +Extensive additional documentation for Perl modules is available. The +default configuration for perl will place this additional documentation +in the F directory (or else in the F +subdirectory of the Perl library directory). Some of this additional +documentation is distributed standard with Perl, but you'll also find +documentation for third-party modules there. + +You should be able to view Perl's documentation with your man(1) +program by including the proper directories in the appropriate start-up +files, or in the MANPATH environment variable. To find out where the +configuration has installed the manpages, type: perl -V:man.dir -If the directories were F and F, -you would need to add only F to your MANPATH. If -they are different, you'll have to add both stems. +If the directories have a common stem, such as F +and F, you need only to add that stem +(F) to your man(1) configuration files or your MANPATH +environment variable. If they do not share a stem, you'll have to add +both stems. If that doesn't work for some reason, you can still use the supplied F script to view module information. You might @@ -94,17 +120,17 @@ Perl combines (in the author's opinion, anyway) some of the best features of C, B, B, and B, so people familiar with those languages should have little difficulty with it. (Language historians will also note some vestiges of B, Pascal, and even -BASIC-PLUS.) Expression syntax corresponds quite closely to C +BASIC-PLUS.) Expression syntax corresponds closely to C expression syntax. Unlike most Unix utilities, Perl does not arbitrarily limit the size of your data--if you've got the memory, Perl can slurp in your whole file as a single string. Recursion is of -unlimited depth. And the tables used by hashes (previously called +unlimited depth. And the tables used by hashes (sometimes called "associative arrays") grow as necessary to prevent degraded -performance. Perl uses sophisticated pattern matching techniques to -scan large amounts of data very quickly. Although optimized for +performance. Perl can use sophisticated pattern matching techniques to +scan large amounts of data quickly. Although optimized for scanning text, Perl can also deal with binary data, and can make dbm files look like hashes. Setuid Perl scripts are safer than C programs -through a dataflow tracing mechanism which prevents many stupid +through a dataflow tracing mechanism that prevents many stupid security holes. If you have a problem that would ordinarily use B or B or @@ -115,197 +141,175 @@ scripts into Perl scripts. But wait, there's more... -Perl version 5 is nearly a complete rewrite, and provides -the following additional benefits: - -=over 5 - -=item * Many usability enhancements +Begun in 1993 (see L), Perl version 5 is nearly a complete +rewrite that provides the following additional benefits: -It is now possible to write much more readable Perl code (even within -regular expressions). Formerly cryptic variable names can be replaced -by mnemonic identifiers. Error messages are more informative, and the -optional warnings will catch many of the mistakes a novice might make. -This cannot be stressed enough. Whenever you get mysterious behavior, -try the B<-w> switch!!! Whenever you don't get mysterious behavior, -try using B<-w> anyway. +=over -=item * Simplified grammar +=item * modularity and reusability using innumerable modules -The new yacc grammar is one half the size of the old one. Many of the -arbitrary grammar rules have been regularized. The number of reserved -words has been cut by 2/3. Despite this, nearly all old Perl scripts -will continue to work unchanged. +Described in L, L, and L. -=item * Lexical scoping +=item * embeddable and extensible -Perl variables may now be declared within a lexical scope, like "auto" -variables in C. Not only is this more efficient, but it contributes -to better privacy for "programming in the large". Anonymous -subroutines exhibit deep binding of lexical variables (closures). +Described in L, L, L, L, +L, and L. -=item * Arbitrarily nested data structures +=item * roll-your-own magic variables (including multiple simultaneous DBM implementations) -Any scalar value, including any array element, may now contain a -reference to any other variable or subroutine. You can easily create -anonymous variables and subroutines. Perl manages your reference -counts for you. +Described in L and L. -=item * Modularity and reusability +=item * subroutines can now be overridden, autoloaded, and prototyped -The Perl library is now defined in terms of modules which can be easily -shared among various packages. A package may choose to import all or a -portion of a module's published interface. Pragmas (that is, compiler -directives) are defined and used by the same mechanism. +Described in L. -=item * Object-oriented programming +=item * arbitrarily nested data structures and anonymous functions -A package can function as a class. Dynamic multiple inheritance and -virtual methods are supported in a straightforward manner and with very -little new syntax. Filehandles may now be treated as objects. +Described in L, L, L, and L. -=item * Embeddable and Extensible +=item * object-oriented programming -Perl may now be embedded easily in your C or C++ application, and can -either call or be called by your routines through a documented -interface. The XS preprocessor is provided to make it easy to glue -your C or C++ routines into Perl. Dynamic loading of modules is -supported, and Perl itself can be made into a dynamic library. +Described in L, L, and L. -=item * POSIX compliant +=item * compilability into C code or Perl bytecode -A major new module is the POSIX module, which provides access to all -available POSIX routines and definitions, via object classes where -appropriate. +Described in L and L. -=item * Package constructors and destructors +=item * support for light-weight processes (threads) -The new BEGIN and END blocks provide means to capture control as -a package is being compiled, and after the program exits. As a -degenerate case they work just like awk's BEGIN and END when you -use the B<-p> or B<-n> switches. +Described in L and L. -=item * Multiple simultaneous DBM implementations +=item * support for internationalization, localization, and Unicode -A Perl program may now access DBM, NDBM, SDBM, GDBM, and Berkeley DB -files from the same script simultaneously. In fact, the old dbmopen -interface has been generalized to allow any variable to be tied -to an object class which defines its access methods. +Described in L and L. -=item * Subroutine definitions may now be autoloaded +=item * lexical scoping -In fact, the AUTOLOAD mechanism also allows you to define any arbitrary -semantics for undefined subroutine calls. It's not for just autoloading. +Described in L. -=item * Regular expression enhancements +=item * regular expression enhancements -You can now specify non-greedy quantifiers. You can now do grouping -without creating a backreference. You can now write regular expressions -with embedded whitespace and comments for readability. A consistent -extensibility mechanism has been added that is upwardly compatible with -all old regular expressions. +Described in L, with additional examples in L. -=item * Innumerable Unbundled Modules +=item * enhanced debugger and interactive Perl environment, with integrated editor support -The Comprehensive Perl Archive Network described in L -contains hundreds of plug-and-play modules full of reusable -code. See F for a site near you. +Described in L. -=item * Compilability +=item * POSIX 1003.1 compliant library -While not yet in full production mode, a working perl-to-C compiler -does exist. It can generate portable bytecode, simple C, or -optimized C code. +Described in L. =back -Ok, that's I enough hype. +Okay, that's I enough hype. + +=head1 AVAILABILITY + +Perl is available for most operating systems, including virtually +all Unix-like platforms. + +As of May 1999, the following platforms are able to build Perl +from the standard source code distribution available at +http://www.perl.com/CPAN/src/index.html + + AIX Linux SCO ODT/OSR + A/UX MachTen Solaris + BeOS MPE/iX SunOS + BSD/OS NetBSD SVR4 + DG/UX NextSTEP Tru64 UNIX 3) + DomainOS OpenBSD Ultrix + DOS DJGPP 1) OpenSTEP UNICOS + DYNIX/ptx OS/2 VMS + FreeBSD OS390 2) VOS + HP-UX PowerMAX Windows 3.1 1) + Hurd QNX Windows 95 1) 4) + IRIX Windows 98 1) 4) + Windows NT 1) 4) + + 1) in DOS mode either the DOS or OS/2 ports can be used + 2) formerly known as MVS + 3) formerly known as Digital UNIX and before that DEC OSF/1 + 4) compilers: Borland, Cygwin, Mingw32 EGCS/GCC, VC++ + +The following platforms have been known to build Perl from source, +but we haven't been able to verify their status for the current release, +either because the hardware/software platforms are rare or +because we don't have an active champion on these platforms--or both. + + 3b1 FPS Plan 9 + AmigaOS GENIX PowerUX + ConvexOS Greenhills RISC/os + CX/UX ISC Stellar + DC/OSx MachTen 68k SVR2 + DDE SMES MiNT TI1500 + DOS EMX MPC TitanOS + Dynix NEWS-OS UNICOS/mk + EP/IX Opus Unisys Dynix + ESIX Unixware + +Support for the following platforms is planned for the next major +Perl release. + + BS2000 + Netware + Rhapsody + VM/ESA + +The following platforms have their own source code distributions and +binaries available via http://www.perl.com/CPAN/ports/index.html. + + Perl release + + AS/400 5.003 + MacOS 5.004 + Netware 5.003_07 + Tandem Guardian 5.004 + +The following platforms have only binaries available via +http://www.perl.com/CPAN/ports/index.html. + + Perl release + + Acorn RISCOS 5.005_02 + AOS 5.002 + LynxOS 5.004_02 =head1 ENVIRONMENT -=over 12 - -=item HOME - -Used if chdir has no argument. - -=item LOGDIR - -Used if chdir has no argument and HOME is not set. - -=item PATH - -Used in executing subprocesses, and in finding the script if B<-S> is -used. - -=item PERL5LIB - -A colon-separated list of directories in which to look for Perl library -files before looking in the standard library and the current -directory. If PERL5LIB is not defined, PERLLIB is used. When running -taint checks (because the script was running setuid or setgid, or the -B<-T> switch was used), neither variable is used. The script should -instead say - - use lib "/my/directory"; - -=item PERL5DB - -The command used to get the debugger code. If unset, uses - - BEGIN { require 'perl5db.pl' } - -=item PERL_DESTRUCT_LEVEL - -Relevant only if your perl executable was built with B<-DDEBUGGING>, -this controls the behavior of global destruction of objects and other -references. - -=item PERLLIB - -A colon-separated list of directories in which to look for Perl library -files before looking in the standard library and the current -directory. If PERL5LIB is defined, PERLLIB is not used. - -=back - -Perl also has environment variables that control how Perl handles data -specific to particular natural languages. See L. - -Apart from these, Perl uses no other environment variables, except -to make them available to the script being executed, and to child -processes. However, scripts running setuid would do well to execute -the following lines before doing anything else, just to keep people -honest: - - $ENV{'PATH'} = '/bin:/usr/bin'; # or whatever you need - $ENV{'SHELL'} = '/bin/sh' if defined $ENV{'SHELL'}; - $ENV{'IFS'} = '' if defined $ENV{'IFS'}; +See L. =head1 AUTHOR -Larry Wall EFE, with the help of oodles of other folks. +Larry Wall , with the help of oodles of other folks. + +If your Perl success stories and testimonials may be of help to others +who wish to advocate the use of Perl in their applications, +or if you wish to simply express your gratitude to Larry and the +Perl developers, please write to perl-thanks@perl.org . =head1 FILES - "/tmp/perl-e$$" temporary file for -e commands "@INC" locations of perl libraries =head1 SEE ALSO a2p awk to perl translator - s2p sed to perl translator + http://www.perl.com/ the Perl Home Page + http://www.perl.com/CPAN the Comphrehensive Perl Archive + =head1 DIAGNOSTICS The B<-w> switch produces some lovely diagnostics. -See L for explanations of all Perl's diagnostics. +See L for explanations of all Perl's diagnostics. The C pragma automatically turns Perl's normally terse warnings +and errors into these longer forms. Compilation errors will tell you the line number of the error, with an indication of the next token or token type that was to be examined. -(In the case of a script passed to Perl via B<-e> switches, each +(In a script passed to Perl via B<-e> switches, each B<-e> is counted as one line.) Setuid scripts have additional constraints that can produce error @@ -319,8 +323,8 @@ switch? The B<-w> switch is not mandatory. Perl is at the mercy of your machine's definitions of various -operations such as type casting, atof(), and sprintf(). The latter -can even trigger a core dump when passed ludicrous input values. +operations such as type casting, atof(), and floating-point +output with sprintf(). If your stdio requires a seek or eof between reads and writes on a particular stream, so does Perl. (This doesn't apply to sysread() @@ -328,15 +332,16 @@ and syswrite().) While none of the built-in data types have any arbitrary size limits (apart from memory size), there are still a few arbitrary limits: a -given variable name may not be longer than 255 characters, and no -component of your PATH may be longer than 255 if you use B<-S>. A regular -expression may not compile to more than 32767 bytes internally. +given variable name may not be longer than 251 characters. Line numbers +displayed by diagnostics are internally stored as short integers, +so they are limited to a maximum of 65535 (higher numbers usually being +affected by wraparound). You may mail your bug reports (be sure to include full configuration -information as output by the myconfig program in the perl source tree, -or by C) to F. -If you've succeeded in compiling perl, the perlbug script in the utils/ -subdirectory can be used to help mail in a bug report. +information as output by the myconfig program in the perl source +tree, or by C) to perlbug@perl.com . If you've succeeded +in compiling perl, the perlbug script in the utils/ subdirectory +can be used to help mail in a bug report. Perl actually stands for Pathologically Eclectic Rubbish Lister, but don't tell anyone I said that.