chown: Change File Owner and Group

chown [OPTION]... [OWNER][:[GROUP]] FILE...
chown [OPTION]... --reference=RFILE FILE...

Argument Results
bob Changes the ownership of the file from its current owner to user bob
bob:users Changes the ownership of the file from its current owner to user bob a changes the file group owner to group users.
:admins Changes the group owner to the group admins. The file owner is unchanged
bob: Changes the file owner from the current owner to user bob and changes the group owner to the login group of user bob.

chgrp: Change Group Ownership

chgrp [OPTION]... GROUP FILE...
chgrp [OPTION]... --reference=RFILE FILE...