Chown
chown changes the user and/or group ownership of a file or directory.
Examples:
chown bob myfile.txt Changes the owner of myfile.txt to bob
chown :office myfile.txt Change just the group of myfile.txt to office.
chown bob:office myfile.txt Change the owner of myfile.txt to bob, and change the group to office
chown bob. myfile.txt Change the owner of myfile.txt to bob, and change the group to the bob group.