Unix Resolution Installation Speed

Question

Is there a significant difference in speed between adding / subtracting permission and setting it explicitly?

For instance:

chmod a+r

against

chmod 755

Answer 1

Yes, there is a difference. Absolute configuration requires one system call ( chmod()). An incremental parameter requires two calls: one to obtain the current permissions ( stat()), and then chmod()to set them. A system call chmod()only works in absolute settings.

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