What does s permission means?

While i run ls -l command on /usr/bin/sudo, it shows

$ ls -l /usr/bin/sudo
-rwsr-xr-x 1 root root 121144 Feb 28 2013 /usr/bin/sudo

What does the s permission means for this sudo file?

1 Answer

s(setuid) means set user ID upon execution. If setuid bit turned on a file, user executing that executable file gets the permissions of the individual or group that owns the file.

$ ls -l /usr/bin/sudo
-rwsr-xr-x 1 root root 121144 Feb 28 2013 /usr/bin/sudo

In this s permission was given to owner, so it represents the file is executable and set-user-ID mode is set.

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