I'll just clarify:
The commands are for system administration and are placed in /sbin or sometimes /usr/sbin.
You can only run programs that you specify the path to, or are in directories that are specified in your $PATH variable.
To change to root and execute root's logon scripts, which should let you run these commands without speficy the path manually use this command:
As you need to be root to make use of those commands anyway there is no point in adding /sbin to your normal user $PATH.