How to break out of a loop in Bash?

while true ; do
    ...
    if [ something ]; then
        break
    fi
done

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.

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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.