#! perl use strict; use warnings; while (my $line = ) { if ($line =~ /C4:46:19:75:C1:55/) { print "ID = ", (split /\s+/, $line)[0], "\n"; } } __DATA__ SS-ID VLAN MAC TIME IP RSSI MODE UAPSD BW GI WMOS DHCP IDENTITY ----- ---- --- ---- -- ---- ---- ----- -- -- ---- ---- -------- 1-1 0 C4:46:19:75:C1:55 23m 192.168.5.253 -24 bgn no 20 S 4.9 ack* 1-2 0 5C:57:C8:69:8C:1E 3s 192.168.5.254 -38 bg no 20 L 4.8 ack*