Perl

Using Modules

• perldoc perllocal = shows what modules have been installed via cpan or manually on the current system
• get cpan if necessary and install (may also need Test::Simple and Digest::SHA to aid in downloading and checking of modules.
• sudo cpan -i Foo::Bar (get name of Foo::Bar from cpan.org)
• perldoc Foo::Bar = see user contributed perl documentation (man pages) of the module you just downloaded

Executables

• cpan
• perldoc = Look up Perl documentation in Pod format.
  • -f perlfunc = look up specific builtin functions, ex: perldoc -f sprintf

Running Perl "perlrun"

• perl -V = Summary of perl5 configuration.
• perl -d and -D = debug options

Syntax

• pass command line arguments using @ARGV, access using $ARGV[n], count with $#ARGV
• indicate end of program using the "__END__" token
• specify certain version of perl by statement "use 5.005_54;" or similar

HTML::Tree module

• my $tree = HTML::TreeBuilder->new_from_file($file_path_string);
• $tree->delete();
• $h->descendents() vs $h->lineage()
• $h->find( 'tag', ... ) = returns a list of elements at or under $h that have any of the specified tag names.
• $h->look_down( ...criteria... ) = THE BIG ONE

my @wide_pix_images = $h->look_down( "_tag", "img", "alt", "pix!", sub { $_[0]->attr(’width’) > 350 });