-u FILE (conditional operator)

true if the file exists and its set-user-id bit is set, i.e. the SETUID bit. false if FILE does not exist or does not have the SETUID bit set.

-g is for the set-group-id bit.

Links

• setuid on Wikipedia
• Bash manual
• POSIX specification of test

Examples

Different ways to test if a file has the SETUID bit set:

1 2 3 4

test -u ~/bin/cmd && echo "SETUID set" [ -u ~/bin/cmd ] && echo "SETUID set" # Bash [[ -u ~/bin/cmd ]] && echo "SETUID set"

Set the SETUID bit:

1	chmod u+s /usr/local/bin/my-cmd