The logic desired if If IP has no PTR, print "PTR_NUL", else print the PTR. dig +short -x 1.2.3.4 | awk '{if ( $0 == "" ) {print "PTR_NUL" } else {print $0 } }' ... works if PTR exist, but if no PTR, PTR_NUL doesn't print. thanks Len ______________________________________________ IMGate OpenSource Mail Firewall www.IMGate.net