1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | #!/bin/bash [ 1 -ne $# ] && { echo "Syntax: $0 ip_address" exit 0 } ping -c1 -W1 $1 >/dev/null ret=$(arp -n | grep "$1" | grep "(incomplete)") [ -n "$ret" ] && { echo "$1 unused" } || { echo "$1 used" } |
Line 2~5: Avoid no parameters.
Line 7: Use ping to learn arp.
Line 9~15: Check arp table and echo message.
