@aral Your standards are what you condone through your silence.

@ekaitz_zarraga `touch` a lock-file before editing and remove it afterward, waiting if it's already present? Or did you already rule that out?
The other thing that springs to mind is to write the file under another name, maybe involving the pid and a timestamp in the filename, then `mv` it over the top of the canonical filepath. Last edit wins, but it's at least atomic.
And that's how you know I'm a sysadmin who writes code, not a pro developer who's been known to administer systems :)