Restart a binary upon change (bash script)

watch.sh

#!/bin/bash

# ---------------------------------------
# EXAMPLE USE:
#
#      ./watch.sh target/debug/my-server-app
# ---------------------------------------

kill_prev_pid () {
  echo Killing prev pid $(cat .pid)
  kill $(cat .pid) 2>/dev/null
}

kill_and_exit () {
  echo Exiting watch...
  kill_prev_pid
  exit 0
}

trap kill_and_exit 1 2 3 6

while :
do
    kill_prev_pid
    $1 &
    PID=$!
    echo New pid $PID
    echo $PID > .pid
    inotifywait $1
    echo Executable file changed - restarting pid $PID
    sleep 2
done