Sudo file explained

In the following 

 entry:

superadm  ALL=(ALL)   ALL

there are four fields:

• The first one specifies a user that will be granted privileges for some command(s).
• The second one is rarely used. It’s a list of hostnames on which this sudo entry will be effective. On standard setups only one host is relevant (localhost) so this field is usually left as 
  ALL

  .

• The fourth field is the list of commands 
  superadm

   will be able to run with elevated privileges. 

  ALL

   means all commands. Otherwise use a comma-separated list of commands.

• The third field (the one written 
  (…)

   that is optional) specifies which users (and groups) the 

  superadm

   user will be able to run the following commands as. 

  ALL

   means they can chose anything (unrestricted). It this field is omitted, it means the same as 

  (root)

  .

Example:

alan   ALL = (root, bin : operator, system) /bin/ls, /bin/kill

Here, 

 is allowed to run the two commands 

 and 

 as 

 (or 

), possibly with additional 

 or 

 groups privileges.

So 

 may chose to run 

 as the 

 user and with 

‘s group privileges like this:

sudo -u bin -g operator /bin/ls /whatever/directory

If 

 is omitted, it’s the same as 

. If 

 is omitted, no additional group privileges are granted.