adduser 

     create a new user for the system

     syntax: 

          adduser [opt] [user]

chfn 

     edit user information for editing or alter of group information, password and more

     syntax:

         chfn [opts] [user]

chsh 

     change login shell

     syntax:

          chsh [opts] [user]

edquota 

     edit the user's disk quota or allowed write disk size (allocation)

     syntax:

        equota [opts] [user]

        ex.:

            $ quota -v (view quota)

            $ quotaon -av (turn on quotas)

last 

     display on screen the list of last logged in users

     syntax:

          last [opts] [tty]

passwd 

     change password for a articular user

     syntax:

           passwd [opts] [user]

           ex.:

               $ passwd -l username (lock a user)

               $ passwd -u username (reverse the lock on the user)

sudo 

     allow root operations by specified users.

     syntax:

            sudo [opts] [command]

useradd 

     adding a New user or create a new user

     syntax:

         useradd [opts] [user]

     ex.:

         # useradd vins -p gu1tarplayer -s /bin/zsh -u 507

     note:

         a new user named vins had been added and his password is gu1tarplayer and his default shell is /bin/zsh and default UID is 507 

userdel 

     delete an existing user from the current user list

     syntax:

           userdel [opts] [user]

uname 

      this option will display the current O/S core version.

      ex.: 

         $ uname -r