What does the 's' attribute in file permissions mean?
That is the "setuid" bit, which tells the OS to execute that program with the userid of its owner. This is typically used with files owned by root to allow normal users to execute them as root with no external tools (such as
You can set the suid bit using
chmod 4755 which will give a file give the normal permissions 755 does (
rwxr-xr-x) and add the suid bit to give
You can clear the setuid bit by issuing a normal chmod command with a 0 prepended to it. For example, to set permissions back to
rwxr-xr-x you would use
Precisely the opposite, you don't need to use sudo or switch to root, the executable does it for you.