test empty port string.

#!/bin/bash -e

port=$1

if pgrep -f $1 &> /dev/null

if [[ ! -z "$port" ]] &&  pgrep -f $port &> /dev/null

then

    kill $(pgrep -f 8001)

    echo Killed process on port $1

    kill $(pgrep -f $port  )

    echo Killed process on port $port

else

   echo "No process on port $1."

   echo "No process on port $port."

fi

exit 0