#! /usr/bin/perl
use warnings;
use strict;

my $file = shift(@ARGV);
unless( defined $file or -f $file ) {
    die "Usage: $0 filename\n";
} # unless

open( my $FH, "<", $file )
    or die "Error: couldn't open file '$file': $!\n";

while( defined my $line = <$FH> ) {
    chomp $line;
    if( $line =~ /something/ ) {
        print "Line found in $.: $line\n";
        last;
    } # if
} # while

close( $FH );