Comment by the8472

Basic atomic filesystem operations support consensus numbers[0] 1 or 2 (via rename and RENAME_EXCHANGE, respectively), but for some concurrent algorithms one needs higher ones. File locks are the only way to get those (if we ignore IPC), and those APIs are a pain.

[0] https://en.wikipedia.org/wiki/Read%E2%80%93modify%E2%80%93wr...