フリー問題

問題文

A default file creation mask of 022 is in effect. A program creates a regular file requesting mode 666. What permissions does the resulting file have, and why?

選択肢

1. Mode 666, because the mask applies only to directories, and a regular file keeps every bit the program requested.
2. Mode 644, because the bits present in the mask are turned off from the requested mode.
3. Mode 022, because the mask replaces the requested mode entirely whenever the requesting program does not have administrative privileges, which is why unprivileged programs cannot create files with permissive modes.
4. Mode 755, because the execute bit is added for the owner on every new file, and the mask is applied afterward only to the group and other bits.