What does it mean for a file to be “setuid?” How do keep track of all setuid enabled file?
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. You need to use the ls -l or find command to see setuid programs. All setuid programs displays S or s in the permission bit (owner-execute) of the ls command. Type the following command:
ls -l /usr/bin/passwd
-rwsr-xr-x 1 root root 42856 2009-07-31 19:29 /usr/bin/passwd