Is this guaranteed to be atomic on all filesystems?
For POSIX, yes.
https://rcrowley.org/2010/01/06/things-unix-can-do-atomicall...
Windows has a deep well of POSIX in the kernel (plus hard file locks), and it appears to hold there.
https://en.wikipedia.org/wiki/Microsoft_POSIX_subsystem
alt Hacker News
For POSIX, yes.
https://rcrowley.org/2010/01/06/things-unix-can-do-atomicall...
Windows has a deep well of POSIX in the kernel (plus hard file locks), and it appears to hold there.
https://en.wikipedia.org/wiki/Microsoft_POSIX_subsystem