Move the user's home directory to the new directory specified with the -d option. Specify the full pathname of the program that is used as the user's shell on login. The value of shell must be a valid executable file. It is generally a short description of the login, and is currently used as the field for the user's full name. This option is useful for creating temporary logins.
Normal values are positive integers.
A value of 0 defeats the status. A usage message for the usermod command is displayed. An invalid argument was provided to an option. The uid given with the -u option is already in use. The password files contain an error.