Объединить 2 строки в одну

#!/bin/bash

timeoffset=43200

while read time macaddr ipaddr hostname __; do
    printf '%s\t%s\t%s\n%(%R)T\n' \
           "$ipaddr" "$hostname" "$macaddr" "$((time - timeoffset))"
done < \
     <(ssh root@192.168.1.1 cat /tmp/dhcp.leases)

awk 'BEGIN { exit 0 }'

ssh root@192.168.1.1 cat /tmp/dhcp.leases | while read time macaddr ipaddr hostname __; do printf '%s\t%s\t%s\t%(%R)T\n' "$ipaddr" "$hostname" "$macaddr" "$((time - 43200))"; done