How to break out of a loop in Bash?
It's not that different in bash.
workdone=0
while : ; do
...
if [ "$workdone" -ne 0 ]; then
break
fi
done
: is the no-op command; its exit status is always 0, so the loop runs until workdone is given a non-zero value.
There are many ways you could set and test the value of workdone in order to exit the loop; the one I show above should work in any POSIX-compatible shell.
while true ; do
...
if [ something ]; then
break
fi
done