Enabling SETUID and SETGID Permissions

Setuid and setgid   permissions can be set within the chmod command through using numeric or symbolic notation for files. Numeric notation needs four octal numbers whenever specifying the setuid or setgid and uses the left-most number to refer to these special permissions.

Table

For executable files

# chmod    4755 setuid_executable file

# chmod    2755 setgid_executable file

For shared directories

#chmod           g+s shared_directory

The setgid bits on a directory have to be set or modified using symbolic notation.

The file or directory which is set to a setuid/setgid program can be checked using the ls command as given below.

$ls -l  setuid_executable file

-rwsr-xr-x        1          root      other    567      Mar      18        19.25 setuid_executable file

-rwxr-sr-x        1          root      other    678      Mar      18        19.27

setgid_executable file

Note: Within some cases "S" (capital S) alter of "s" could be found in the output of ls -l command for a setuid or setgid file that display an error condition in which the setuid or setgid bit is set but the execute bit is off.