use strict; my %hash; foreach() { $hash{$1}=() if /JSESSIONID=(.*)$/; } foreach (sort keys %hash) { print $_."\n"; } __DATA__ [17/May/2005:18:15:59 -0700]sdjhsj USERID=t70xvcy; jdhdh JSESSIONID=0000RDnYTABcRWOx0UN2Zq--sZB:10f408hdg [17/May/2005:18:15:59 -0700]sdjhsj USERID=t70xvcy; jdhdh JSESSIONID=0000RDnYTABcRWOx0UN2Zq--sZB:10f408hdg [17/May/2005:18:15:59 -0700]sdjhsj USERID=t70xvcy; jdhdh JSESSIONID=0000RDnYTABcRWOx0UN2Zq--sZB:10f408g13