Unix
Users kirk and picard are members of the captains group. User worf is a member of the klingons group. # touch x.x # echo hello >> x.x # chown kirk:captains x.x # chmod 640 x.x # ls -l x.x -rw-r----- 1 kirk captains 6 Mar 17 09:33 x.x kirk $ cat x.x hello ...