Table of Contents

Name

perl - Practical Extraction and Report Language

Synopsis

perl [ -sTtuUWX ]
[ -hv ] [ -V[:configvar] ] [ -cw ] [ -d[t][:debugger] ] [ -D[number/list] ] [ -pna ] [ -Fpattern ] [ -l[octal] ] [ -0[octal/hexadecimal] ] [ -Idir ] [ -m[-]module ] [ -M[-]’module...’ ] [ -f ]
[ -C [number/list] ]
[ -P ] [ -S ] [ -x[dir] ]
[ -i[extension] ]
[ -e ‘command’ ] [ -- ] [ program_file ] [ argument ]...

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

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

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
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
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

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 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.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 perldiag 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 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 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.


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