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 either sh(1) or csh(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).

Login times out and exits if its prompt for input is not answered within some ‘reasonable’ time. 

When the Bourne Shell (sh(1)) starts up, it reads a file called .profile from the user’s home directory.  When the C-Shell (sh(1)) starts up, it reads a file called .login from the user’s home directory, and reads a file called .cshrc from the user’s home directory every time a new C-Shell is started.  Note that the Shells only read these files if they are owned by the person who is logging in — these files are not read when login is being used to change user i.d. 

FILES

/etc/utmpaccounting
/usr/adm/wtmpaccounting
/usr/spool/mail/∗mail
/etc/motdmessage-of-the-day
/etc/passwdpassword file
/etc/nologinstops logins
.hushloginmakes login quieter

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”: ask your system administrator for assistance.

Sun Release 2.0  —  Last change: 1 February 1985