#!/bin/sh
#
# witness - watch a file for changes & run a command

file="$1"
shift
command="$@"

get_access_time() {
    stat -c %Z "$1"
}

ltime="$(get_access_time "$file")"

while true; do
    atime="$(get_access_time "$file")"
    if [ "$atime" != "$ltime" ]; then
        printf "witness: '%s' changed, running '%s'\n" "$file" "$command"
        $command
	ltime="$atime"
    fi
    sleep 0.5
done