using Term::Readline

 my $term = Term::ReadLine->new('some identifier');
 my $str = $term->readline('prompt> ');
 the basic stdin-based Term::ReadLine is built into perl
 but if the user installs the Gnu ReadLine stuff it will be available transparently



using a module only if it's available:
BEGIN {
  eval {
    require Devel::Size;
    Devel::Size->import qw/total_size/;
  };
}

if($INC{'Devel/Size.pm'})
{
  # foooooo
}




use FindBin qw($RealBin);
use lib "$RealBin/lib/perl";


Perl command line args:
-n wrap in a while loop
-p auto print
-l auto chomp and add linefeed
-i inplace (asin sed)
-a auto split lines into @F