NAME

login − sign on

SYNOPSIS

login [ username ]

DESCRIPTION

Login signs username on to the system initially; login may also be used at any time to change from one user i.d. to another. 

If you use login without an argument, login requests a user name, and a password if appropriate.  Echoing is turned off (if possible) during the typing of the password, so it will not appear on the written record of the session. 

After a successful login, accounting files are updated, the user is informed of the existence of mail, and the message of the day is printed, as is the time he last logged in (unless he has a .hushlogin file in his home directory − this is mainly used to make life easier for non-human users, such as uucp).

Login initializes the user and group IDs and the working directory, then executes a command interpreter (usually sh(1)) according to specifications found in a password file. Argument 0 of the command interpreter is “−sh”, or more generally the name of the command interpreter with a leading dash (“−”) prepended.

Login also initializes the environment environ(5) with information specifying home directory, command interpreter, terminal type (if available) and user name.

If the file /etc/nologin exists, login prints its contents on the user’s terminal and exits. This is used by shutdown(8) to stop logins when the system is about to go down.

Login is recognized by sh(1) and csh(1) and executed directly (without forking).

FILES

/etc/utmpaccounting
/usr/adm/wtmpaccounting
/usr/spool/mail/∗mail
/etc/motdmessage-of-the-day
/etc/passwdpassword file
/etc/nologinstops logins
.hushloginmakes login quieter
/etc/securettylists ttys that root may log in on

SEE ALSO

init(8), getty(8), mail(1), passwd(1), passwd(5), environ(5), shutdown(8)

DIAGNOSTICS

“Login incorrect,” if the name or the password is bad (or mis-typed). 
“No Shell”, “cannot open password file”, “no directory”: consult a programming counselor.

Sun System Release 1.0  —  1 November 1983