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CompTIA Linux+ XK0-006 · Domain 3: Security

Special permissions: SUID, SGID, sticky bit; ACLs with setfacl and getfacl

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Last reviewed September 30, 2026 · Leer en español

Beyond the basic rwx bits, Linux has three special permission bits and optional ACLs (access control lists). They solve real problems, such as letting users change their own password or share a directory safely, but they also create risk if misused, so the exam covers both their use and their security implications. Each special bit appears as a letter in one of the three execute positions of ls -l.

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