#!/usr/bin/perl -w
use strict;

my $config_file = "/home/foo/bar";
read_conf($config_file);

#  el fin

#  this subroutine in RL actually does something,
#  but that is outside the scope of the question ;)
sub read_conf {
  my $conf_file = @_;
  open (CONF, "$conf_file") or die "[ $conf_file ]: $!\n";
}