how about using a symbolic link?

For instance, suppose you have foo-1 and foo.link pointing to foo-1. To update it, first create foo-2, then change its permissions and finally point foo.link to foo-2.

The point is that foo.link can have more relaxed permissions, i.e., 644

In reply to Re^3: Writing to a file atomically without renaming by salva
in thread Writing to a file atomically without renaming by nomis80

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