When user logged on, type "Login". Comes back with "password", type
password comes back again with "Password" type password again. Comes
back "login" incorrect. After successful login by typing login name
instead of password, Keyboard key strokes are not echoed until <CR> is
pressed. Pressing just <CR> does not echo Line Feed <LF>.
Unlike other un*xes, the Linux login is responsible for maintaining a
PAM session, and so cannot support use from the command line.
Try "su - user" instead.