#!/usr/local/bin/perl -w
use strict;
my $usage = "Usage: gtail <filename> <options for grep>\n";
my $file = shift or die $usage;
@ARGV or die $usage;
open(TAIL, "tail -f $file|") or die "Can't pipe from tail: $!";
open(GREP, "|grep @ARGV") or die "Can't pipe to grep: $!";
select((select(GREP), $|=1)[0]);
while(<TAIL>) { print GREP $_; }