#!/bin/sh

leasestarttime="$(awk -F'.' '{print $1}' /proc/uptime 2> /dev/null)"
target_file=/tmp/dhcp_client_info
target_str="$INTERFACE $lease $leasestarttime"

# if this interface is present in file, then replace it
if grep -q "$INTERFACE" "$target_file" 2> /dev/null; then
	# replace the whole line if pattern matches
	sed -i "/${INTERFACE}/c\\${target_str}" "$target_file"
else
	# interface info was not present, append it to the file
	echo "$target_str" >> "$target_file"
fi