The shell is your interface to UNIX. If you make a bad mistake when you change your, or your password, it can be tough to log in and fix things.
Before you change your setup, it's a good idea to start a login session to the same account from somewhere else. Use that session for making your changes. Log in again elsewhere to test your changes.
vi .cshrc...Make edits to the file... somehost%
rlogin localhost...Logs you in to your same account...
An error messagesomehost%
logoutConnection closed. somehost%
vi .cshrc...Edit to fix mistake...