SSH Reverse shell with handling for killing "stale" instances and restarting tunnels if they die or get killed

reversh

#!/usr/bin/bash
# Start ssh reverse shell tunnel; but also poll and restart as necessary
# checks for previously running tunnel and kills it if found
# Enhancement to: http://www.thegeekstuff.com/2013/11/reverse-ssh-tunnel/

STALEPID=$(ps faxwww | grep '[7]000:localhost:22' | cut -d' ' -f1)
[ -n "$STALEPID" ] && {
    echo 'Killing previous (stale?) tunnel' >&2
    kill "$STALEPID"
    kill -0 "$STALEPID" && kill -9 "$STALEPID"
    }

while :; do
    ssh -fN -R 7000:localhost:22 "$user@$pubhost" || {
        echo 'Unable to establish tunnel' >&2
        sleep 10
        continue
        }
    PID=$(ps faxwww | grep '[7]000:localhost:22' | cut -d' ' -f1) || {
        echo "Unable to find tunnel process $PID" >&2
        sleep 5
        continue
        }
    while sleep 30; do #
        kill -0 "$PID" || break
        done
    done