neo's solution?

gistfile1.sh

#!/usr/bin/env bash

MYCOMMAND='while [ true ]; do sleep 1; echo "beje"; done'

# This will take down the whole process tree on ctrl+c
trap "exit" INT TERM
trap "kill 0" EXIT

while true; do
    sleep 1;
    NEW_OUTPUT=`find . -name \*.coffee -exec openssl sha1 {} \;`;
    
    if [ "$NEW_OUTPUT" != "$OLD_OUTPUT" ]
    then
        # echo "changed!";
        if [ "$MYPID" ]; then kill -9 $MYPID; fi
        bash -c "$MYCOMMAND" &  # command will output to stdout
        MYPID=$!
        OLD_OUTPUT="$NEW_OUTPUT";
    fi

done