perl - Practical Extraction and Report Language

- NAME
- SYNOPSIS

- Overview
- Tutorials
- Reference Manual
- Internals and C Language Interface
- Miscellaneous
- Language-Specific
- Platform-Specific

- DESCRIPTION
- AVAILABILITY
- ENVIRONMENT
- AUTHOR
- FILES
- SEE ALSO
- DIAGNOSTICS
- BUGS
- NOTES

# NAME

perl - Practical Extraction and Report Language

# SYNOPSIS

perl | [ -sTtuUWX ]
| [ -hv ] [ -V[:configvar] ]
| [ -cw ] [ -d[t][:debugger] ] [ -D[number/list] ]
| [ -pna ] [ -F pattern ] [ -l[octal] ] [ -0[octal/hexadecimal] ]
| [ -I dir ] [ -m[-]module ] [ -M[-]'module...' ] [ -f ]
| [ -C [number/list] ]
| [ -P ]
| [ -S ]
| [ -x[dir] ]
| [ -i[extension] ]
| [ -e 'command' ] [ -- ] [ programfile ] [ argument ]...

If you're new to Perl, you should start with the perlintro manpage, 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
        perlrebackslash     Perl regular expression backslash sequences
        perlrecharclass     Perl regular expression character classes
        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
        perlunifaq          Perl Unicode FAQ
        perlunitut          Perl Unicode tutorial
        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
        perlpragma          Perl modules: writing a user pragma

        perlutil            utilities packaged with the Perl distribution

        perlcompile         Perl compiler suite intro

        perlfilter          Perl source filters

        perlglossary        Perl Glossary

## 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
        perlreapi           Perl regular expression plugin interface
        perlreguts          Perl regular expression engine internals

        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
        perlcommunity       Perl community information
        perltodo            Perl things to do

        perldoc             Look up Perl documentation in Pod format

        perlhist            Perl history records
        perldelta           Perl changes since previous version
        perl595delta        Perl changes in version 5.9.5
        perl594delta        Perl changes in version 5.9.4
        perl593delta        Perl changes in version 5.9.3
        perl592delta        Perl changes in version 5.9.2
        perl591delta        Perl changes in version 5.9.1
        perl590delta        Perl changes in version 5.9.0
        perl588delta        Perl changes in version 5.8.8
        perl587delta        Perl changes in version 5.8.7
        perl586delta        Perl changes in version 5.8.6
        perl585delta        Perl changes in version 5.8.5
        perl584delta        Perl changes in version 5.8.4
        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
        perllinux           Perl notes for Linux
        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
        perlopenbsd         Perl notes for OpenBSD
        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
        perlriscos          Perl notes for RISC OS
        perlsolaris         Perl notes for Solaris
        perlsymbian         Perl notes for Symbian
        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

By default, the manpages listed above are installed in the /usr/local/man/ directory.

Extensive additional documentation for Perl modules is available. The default configuration for perl will place this additional documentation in the /usr/local/lib/perl5/man directory (or else in the man 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 have a common stem, such as /usr/local/man/man1 and /usr/local/man/man3, you need only to add that stem (/usr/local/man) 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 perldoc script to view module information. You might also look into getting a replacement man program.

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.

# 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.

But wait, there's more...

Begun in 1993 (see the perlhist manpage), Perl version 5 is nearly a complete rewrite that provides the following additional benefits:

- modularity and reusability using innumerable modules

  Described in the perlmod manpage, the perlmodlib manpage, and the perlmodinstall manpage.

- embeddable and extensible

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

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

  Described in the perltie manpage and the AnyDBM_File manpage.

- subroutines can now be overridden, autoloaded, and prototyped

  Described in the perlsub manpage.

- arbitrarily nested data structures and anonymous functions

  Described in the perlreftut manpage, the perlref manpage, the perldsc manpage, and the perllol manpage.

- object-oriented programming

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

- support for light-weight processes (threads)

  Described in the perlthrtut manpage and the threads manpage.

- support for Unicode, internationalization, and localization

  Described in the perluniintro manpage, the perllocale manpage and the Locale::Maketext manpage.

- lexical scoping

  Described in the perlsub manpage.

- regular expression enhancements

  Described in the perlre manpage, with additional examples in the perlop manpage.

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

  Described in the perldebtut manpage, the perldebug manpage and the perldebguts manpage.

- POSIX 1003.1 compliant library

  Described in the POSIX manpage.

Okay, that's definitely enough hype.

# AVAILABILITY

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

# ENVIRONMENT

See the perlrun manpage.

# 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.org/       the Perl homepage
     http://www.perl.com/       Perl articles (O'Reilly)
     http://www.cpan.org/       the Comprehensive Perl Archive
     http://www.pm.org/         the Perl Mongers

# DIAGNOSTICS

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

See the perldiag manpage for explanations of all Perl's diagnostics. The `use diagnostics` 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 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 the perlsec manpage.

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 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 `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.

perl - Practical Extraction and Report Language