Difference between revisions of "Perl"

Latest revision as of 04:15, 31 March 2008

Perl is a dynamic programming language.

see: scripts for examples

Regex

see: Regular expression

Search and replace all "foo" with "bar" in filename:

perl -i -pe 's/foo/bar/gi' filename

Modules

Search and download: http://search.cpan.org/

Installing

perl -MCPAN -e shell
#Or,
perl -MCPAN -e "install Example::Module"

My favourites

• Perl/Modules/Lingua
• DBI
• Regexp::Common
• Math::Bezier
• WWW::Mechanize (see: [1])
• WWW::Search::PubMed (see: [2])
• WWW::Search::NCBI::PubMed
• LWP::Simple — simple procedural interface to LWP
• Math::Polynomial::Solve
• Lingua::EN::Keywords
• MediaWiki
• ack — a grep-like tool
• mvs

Upgrade CPAN

% perl -MCPAN -e shell
cpan>install Bundle::CPAN
cpan>q

• Force CPAN to produce a list of all the modules that have updates and update them:

/usr/bin/perl -MCPAN -e 'CPAN::Shell->install(CPAN::Shell->r)'

Perlrun

Here is an excerpt from 'man perlrun' about the important command line switches used when doing perl one-liners.

    -a   turns on autosplit mode when used with a -n or -p.  An implicit
         split command to the @F array is done as the first thing inside the
         implicit while loop produced by the -n or -p.
              perl -ane 'print pop(@F), "\n";'
         is equivalent to
             while (<>) {
                 @F = split(' ');
                 print pop(@F), "\n";
             }
         An alternate delimiter may be specified using -F.

    -e commandline
         may be used to enter one line of script.  If -e is given, Perl will
         not look for a script filename in the argument list.  Multiple -e
         commands may be given to build up a multi-line script.  Make sure to
         use semicolons where you would in a normal program.

    -n   causes Perl to assume the following loop around your script, which
         makes it iterate over filename arguments somewhat like sed -n or
         awk:
             while (<>) {
                 ...             # your script goes here
             }
         Note that the lines are not printed by default.  See -p to have
         lines printed.  If a file named by an argument cannot be opened for
         some reason, Perl warns you about it, and moves on to the next file.

    -p   causes Perl to assume the following loop around your script, which
         makes it iterate over filename arguments somewhat like sed:
             while (<>) {
                 ...             # your script goes here
             } continue {
                 print or die "-p destination: $!\n";
             }
         If a file named by an argument cannot be opened for some reason,
         Perl warns you about it, and moves on to the next file.  Note that
         the lines are printed automatically.  An error occuring during
         printing is treated as fatal.  To suppress printing use the -n
         switch.  A -p overrides a -n switch.

BioPerl

See: http://www.bioperl.org/wiki/Main_Page

See also

• Perl functions A-Z
• perlop — Perl operators
• CPANPLUS (aka CPAN++) — a more modern version of CPAN.pm

External links

• Perl version 5.8.8 documentation
• Perl regular expressions
• perlrequick — Perl regular expressions quick start
• perlretut — Perl regular expressions tutorial
• "Beginning Perl" — full book online (as PDFs).
• Perl/Python Phrasebook
• Rosetta Code
• Yet Another Rosetta Code Problem (Perl, Ruby, Python, Haskell, ...)
• Text manipulation tools — from GNU/Linux Command-Line Tools Summary
• Mandriva Perl library packaging policy (wiki)
• wikipedia:Perl
• wikipedia:Plain Old Documentation (aka POD)

Resources/Books

• Minimal Perl: For UNIX and Linux People by Tim Maher. ISBN 1-9323-9450-8.