Helloe, i have a bash script that i need help with:

#!/bin/bash
if [ -f "/suid.old" ]
then
find / -perm -4000 -o -perm -2000 ls > suid.old
else
find / -perm 4000 -o -perm -2000 ls > suid.new

diff suid.old suid.new > newchanges.list
fi

when i run it it gives me an error saying: diff: suid.old: No such file or directory.

My script should say, if suid.old does not exist, then use the find command to create one, or else use find command to do whatever it needs to with the suid.new. after find any changes it made and redirect it to newchanges.list

please help,