perl (manpage)

Computing: Software: Programming: Perl: Manpage

Manpage

NAME

perl - Practical Extraction and Report Language

SYNOPSIS

perl

1. REDIRECT Template:arg/opt
2. REDIRECT Template:fmt/arg/opt [ <-V[:configvar]> ] [ <-cw> ] [ <-d[:debugger]> ] [ <-D[number/list]> ] [ <-pna> ] [ <-Fpattern> ] [ <-l[octal]> ] [ <-0[octal]> ] [ <-Idir> ] [ <-m[-]module> ] [ <-M[-]'module...'> ] [ <-P> ] [ <-S> ] [ <-x[dir]> ] [ <-i[extension]> ] [ <-e 'command'> ] [ <--> ] [ <programfile> ] [ <argument> ]...

DESCRIPTION

Perl is a language optimized for scanning arbitrary text files, extracting information from those text files, and printing reports based on that information. It's also a good language for many system management tasks. The language is intended to be practical (easy to use, efficient, complete) rather than beautiful (tiny, elegant, minimal).

Perl combines (in the author's opinion, anyway) some of the best features of C, sed, awk, and sh, so people familiar with those languages should have little difficulty with it. (Language historians will also note some vestiges of csh, Pascal, and even 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 (sometimes called "associative arrays") grow as necessary to prevent degraded 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 that prevents many stupid security holes.

If you have a problem that would ordinarily use sed or awk or sh, but it exceeds their capabilities or must run a little faster, and you don't want to write the silly thing in C, then Perl may be for you. There are also translators to turn your sed and awk scripts into Perl scripts.

If you're new to Perl, you should start with perlintro, which is a general intro for beginners and provides some background to help you navigate the rest of Perl's extensive documentation.

For ease of access, the Perl manual has been split up into several sections.

Overview

perl	Perl overview (this section)
perlintro	Perl introduction for beginners
perltoc	Perl documentation table of contents

Tutorials

perlreftut	Perl references short introduction
perldsc	Perl data structures intro
perllol	Perl data structures: arrays of arrays
perlrequick	Perl regular expressions quick start
perlretut	Perl regular expressions tutorial
perlboot	Perl OO tutorial for beginners
perltoot	Perl OO tutorial, part 1
perltooc	Perl OO tutorial, part 2
perlbot	Perl OO tricks and examples
perlstyle	Perl style guide
perlcheat	Perl cheat sheet
perltrap	Perl traps for the unwary
perldebtut	Perl debugging tutorial
perlfaq	Perl frequently asked questions
	perlfaq1 General Questions About Perl perlfaq2 Obtaining and Learning about Perl perlfaq3 Programming Tools perlfaq4 Data Manipulation perlfaq5 Files and Formats perlfaq6 Regexes perlfaq7 Perl Language Issues perlfaq8 System Interaction perlfaq9 Networking

Reference Manual

perlsyn	Perl syntax
perldata	Perl data structures
perlop	Perl operators and precedence
perlsub	Perl subroutines
perlfunc	Perl built-in functions
	perlopentut Perl open() tutorial perlpacktut Perl pack() and unpack() tutorial
perlpod	Perl plain old documentation
perlpodspec	Perl plain old documentation format specification
perlrun	Perl execution and options
perldiag	Perl diagnostic messages
perllexwarn	Perl warnings and their control
perldebug	Perl debugging
perlvar	Perl predefined variables
perlre	Perl regular expressions, the rest of the story
perlreref	Perl regular expressions quick reference
perlref	Perl references, the rest of the story
perlform	Perl formats
perlobj	Perl objects
perltie	Perl objects hidden behind simple variables perldbmfilter Perl DBM filters
perlipc	Perl interprocess communication
perlfork	Perl fork() information
perlnumber	Perl number semantics
perlthrtut	Perl threads tutorial perlothrtut Old Perl threads tutorial
perlport	Perl portability guide
perllocale	Perl locale support
perluniintro	Perl Unicode introduction
perlunicode	Perl Unicode support
perlebcdic	Considerations for running Perl on EBCDIC platforms
perlsec	Perl security
perlmod	Perl modules: how they work
perlmodlib	Perl modules: how to write and use
perlmodstyle	Perl modules: how to write modules with style
perlmodinstall	Perl modules: how to install from CPAN
perlnewmod	Perl modules: preparing a new module for distribution
perlutil	utilities packaged with the Perl distribution
perlcompile	Perl compiler suite intro
perlfilter	Perl source filters

Internals and C Language Interface

          perlembed           Perl ways to embed perl in your C or C++ application
          perldebguts         Perl debugging guts and tips
          perlxstut           Perl XS tutorial
          perlxs              Perl XS application programming interface
          perlclib            Internal replacements for standard C library functions
          perlguts            Perl internal functions for those doing extensions
          perlcall            Perl calling conventions from C

          perlapi             Perl API listing (autogenerated)
          perlintern          Perl internal functions (autogenerated)
          perliol             C API for Perl's implementation of IO in Layers
          perlapio            Perl internal IO abstraction interface

          perlhack            Perl hackers guide

      Miscellaneous

          perlbook            Perl book information
          perltodo            Perl things to do

          perldoc             Look up Perl documentation in Pod format

          perlhist            Perl history records
          perldelta           Perl changes since previous version
          perl583delta        Perl changes in version 5.8.3
          perl582delta        Perl changes in version 5.8.2
          perl581delta        Perl changes in version 5.8.1
          perl58delta         Perl changes in version 5.8.0
          perl573delta        Perl changes in version 5.7.3
          perl572delta        Perl changes in version 5.7.2
          perl571delta        Perl changes in version 5.7.1
          perl570delta        Perl changes in version 5.7.0
          perl561delta        Perl changes in version 5.6.1
          perl56delta         Perl changes in version 5.6
          perl5005delta       Perl changes in version 5.005
          perl5004delta       Perl changes in version 5.004

          perlartistic        Perl Artistic License
          perlgpl             GNU General Public License

      Language-Specific

          perlcn              Perl for Simplified Chinese (in EUC-CN)
          perljp              Perl for Japanese (in EUC-JP)
          perlko              Perl for Korean (in EUC-KR)
          perltw              Perl for Traditional Chinese (in Big5)

      Platform-Specific

          perlaix             Perl notes for AIX
          perlamiga           Perl notes for AmigaOS
          perlapollo          Perl notes for Apollo DomainOS
          perlbeos            Perl notes for BeOS
          perlbs2000          Perl notes for POSIX-BC BS2000
          perlce              Perl notes for WinCE
          perlcygwin          Perl notes for Cygwin
          perldgux            Perl notes for DG/UX
          perldos             Perl notes for DOS
          perlepoc            Perl notes for EPOC
          perlfreebsd         Perl notes for FreeBSD
          perlhpux            Perl notes for HP-UX
          perlhurd            Perl notes for Hurd
          perlirix            Perl notes for Irix
          perlmachten         Perl notes for Power MachTen
          perlmacos           Perl notes for Mac OS (Classic)
          perlmacosx          Perl notes for Mac OS X
          perlmint            Perl notes for MiNT
          perlmpeix           Perl notes for MPE/iX
          perlnetware         Perl notes for NetWare
          perlos2             Perl notes for OS/2
          perlos390           Perl notes for OS/390
          perlos400           Perl notes for OS/400
          perlplan9           Perl notes for Plan 9
          perlqnx             Perl notes for QNX
          perlsolaris         Perl notes for Solaris
          perltru64           Perl notes for Tru64
          perluts             Perl notes for UTS
          perlvmesa           Perl notes for VM/ESA
          perlvms             Perl notes for VMS
          perlvos             Perl notes for Stratus VOS
          perlwin32           Perl notes for Windows

      On Debian systems, you need to install the perl-doc package which contains the majority of the
      standard Perl documentation and the perldoc program.

      Extensive additional documentation for Perl modules is available, both those distributed with
      Perl and third-party modules which are packaged or locally installed.

      You should be able to view Perl's documentation with your man(1) program or perldoc(1).

      If something strange has gone wrong with your program and you're not sure where you should look
      for help, try the -w switch first.  It will often point out exactly where the trouble is.

      But wait, there's more...
      Begun in 1993 (see perlhist), Perl version 5 is nearly a complete rewrite that provides the
      following additional benefits:

      ·   modularity and reusability using innumerable modules

          Described in perlmod, perlmodlib, and perlmodinstall.

      ·   embeddable and extensible

          Described in perlembed, perlxstut, perlxs, perlcall, perlguts, and xsubpp.

      ·   roll-your-own magic variables (including multiple simultaneous DBM implementations)

          Described in perltie and AnyDBM_File.

      ·   subroutines can now be overridden, autoloaded, and prototyped

          Described in perlsub.

      ·   arbitrarily nested data structures and anonymous functions

          Described in perlreftut, perlref, perldsc, and perllol.

      ·   object-oriented programming

          Described in perlobj, perlboot, perltoot, perltooc, and perlbot.

      ·   support for light-weight processes (threads)

          Described in perlthrtut and threads.

      ·   support for Unicode, internationalization, and localization

          Described in perluniintro, perllocale and Locale::Maketext.

      ·   lexical scoping

          Described in perlsub.

      ·   regular expression enhancements

          Described in perlre, with additional examples in perlop.

      ·   enhanced debugger and interactive Perl environment, with integrated editor support

          Described in perldebtut, perldebug and perldebguts.

      ·   POSIX 1003.1 compliant library

          Described in POSIX.

      Okay, that's definitely enough hype.

AVAILABILITY

      Perl is available for most operating systems, including virtually all Unix-like platforms.  See
      "Supported Platforms" in perlport for a listing.

ENVIRONMENT

      See perlrun.

AUTHOR

      Larry Wall <larry@wall.org>, 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 .

FILES

       "@INC"                 locations of perl libraries

SEE ALSO

       a2p    awk to perl translator
       s2p    sed to perl translator

       http://www.perl.com/       the Perl Home Page
       http://www.cpan.org/       the Comprehensive Perl Archive
       http://www.perl.org/       Perl Mongers (Perl user groups)

DIAGNOSTICS

      The "use warnings" pragma (and the -w switch) produces some lovely diagnostics.

      See perldiag for explanations of all Perl's diagnostics.  The "use diagnostics" pragma automat-
      ically 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 a script passed to Perl via -e switches, each
      -e is counted as one line.)

      Setuid scripts have additional constraints that can produce error messages such as "Insecure
      dependency".  See perlsec.
      Did we mention that you should definitely consider using the -w switch?

BUGS

      The -w switch is not mandatory.

      Perl is at the mercy of your machine's definitions of various 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() 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 251 char-
      acters.  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 "perl -V") to perlbug@perl.org .  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.

NOTES

      The Perl motto is "There's more than one way to do it."  Divining how many more is left as an
      exercise to the reader.

      The three principal virtues of a programmer are Laziness, Impatience, and Hubris.  See the
      Camel Book for why.