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PERL   (1) manpage
PERL
1
2004-11-05
perl v5.8.6
Perl Programmers Reference Guide
  • NAME
      perl - Practical Extraction and Report Language
  • SYNOPSIS
      perl [ -sTuU ] [ -hv ] [ -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 ]...

      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
          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
          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


      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 Media)
      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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