Linux · ACLs, Special Bits & Attributes

The setgid bit means one thing on an executable and something completely different on a directory. What are the two behaviors?

Answer locked. Get the free KnowCard app to reveal it — plus spaced-repetition review so it actually sticks.

This is one card from the KnowCard library — thousands more across SAP, Linux, Python and more. In the app you get the answer, AI explanations, and cards that come back right before you would forget them. Free to start on iOS, Android or the web.

More in ACLs, Special Bits & Attributes

An unprivileged user runs passwd and successfully edits /etc/shadow, a file only root can write. How is that possible without giving the user root?

In ls -l you see -rwsr-xr-x on a binary. What does the s mean, what octal bit produced it, and how do you list every such program?

You add a setuid bit to a Python script hoping it will run as root. Why does it silently fail to give root privileges?

/tmp is world-writable, yet one user cannot delete another user's temp files. What mechanism enforces that?

In ls -l output, an uppercase S or T appears instead of a lowercase s or t. What does the capital letter signal?

You run chmod 0770 on a directory to strip its setgid bit, but ls -l shows the bit is still there. Why, and how do you actually remove it?

Start learning today

Free to start — download the app or use it in your browser.