users
- adduser
- /etc/skel
- add them to a group
  + addgroup
  + adduser joe sudo
  + edit /etc/group file
- ownership
  + chown
- permissions
  + traditionally 3 digits (0755)
  + read = r = 4, write = w = 2, execute = x = 1
  + chmod
    * octal = 755 
    * symbolic =  chmod u=rwx,g=rx,o=rx
    * result= rwxr-xr-x
  + sticky bit = only set on directories, only the user that created can delete (1)
  + setuid = sets the user id..., for a file, ensures the file runs as the user that owns the file (4)
  + setgid =  applies to dir, new files will automatically be owned by the group (2)
- umask
  + what permission are denied?
  + what permissions are subtracted from the default
    - files: 666 (rw-rw-rw-)
      umask: 037 (----wxrwx)
      result:    (rw-r-----)(640)
    - dirs: 777 (rwxrwxrwx)
      umask: 037(----wxrwx)
      result:   (rwxr-----)(740)
  + set in /etc/skel  (applies to new users, created adduser)

Good luck.