UNIX command for changing permissions. Each file is assigned permissions based upon the ownership, the group membership, and the accessibility of the file to non-authenticated users. Permissions are assigned in a combination of three variants: Read permission (assigned a numeric value of 4) allows a user to view the contents of a file or a directory. Write permission (assigned a numeric value of 2) allows a user to view and make changes to a file. Execute permission (assigned a numeric value of 1) allows a user to run the program contained in a file. Only the owner of the file or directory can change permissions UNIX clients can modify permissions through an F.T.P. client, such as CuteFTP or WS-FTP.