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 ] [ -- ] [ programfile ] [ argument ]...
If youre 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 Perls 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 Perls 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 youll also find documentation for third-party modules there.
You should be able to view Perls 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, youll have to add both stems.
If that doesnt 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 youre 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. Its 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 authors 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 dataif youve 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 dont 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, theres more...
Begun in 1993 (see perlhist), Perl version 5 is nearly a complete rewrite that provides the following additional benefits:
o |
modularity and reusability using innumerable modules
Described in perlmod, perlmodlib, and perlmodinstall. |
o |
embeddable and extensible
Described in perlembed, perlxstut, perlxs, perlcall, perlguts, and xsubpp. |
o |
roll-your-own magic variables (including multiple simultaneous DBM
implementations)
Described in perltie and AnyDBM_File. |
o |
subroutines can now be overridden, autoloaded, and prototyped
Described in perlsub. |
o |
arbitrarily nested data structures and anonymous functions
Described in perlreftut, perlref, perldsc, and perllol. |
o |
object-oriented programming
Described in perlobj, perlboot, perltoot, perltooc, and perlbot. |
o |
support for light-weight processes (threads)
Described in perlthrtut and threads. |
o |
support for Unicode, internationalization, and localization
Described in perluniintro, perllocale and Locale::Maketext. |
o |
lexical scoping
Described in perlsub. |
o |
regular expression enhancements
Described in perlre, with additional examples in perlop. |
o |
enhanced debugger and interactive Perl environment,
with integrated editor support
Described in perldebtut, perldebug and perldebguts. |
o |
POSIX 1003.1 compliant library
Described in POSIX. |
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
DIAGNOSTICS
The use warnings pragma (and the -w switch) produces some lovely diagnostics.
See perldiag for explanations of all Perls diagnostics. The use diagnostics pragma automatically turns Perls 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 machines 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 doesnt 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 youve 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 dont tell anyone I said that.
NOTES
The Perl motto is Theres 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.