NAME

login − sign on

DESCRIPTION

The login command is used at the beginning of each terminal session and allows you to identify yourself to the system.  It can no longer be invoked explicitly, but is invoked by the system when a connection is first established, or after the previous user has logged out by sending an “end-of-file” (control−D) to his or her initial shell.  (See How to Get Started at the beginning of this volume for instructions on how to dial up initially.) 

Login asks for your user name, and, if appropriate, your password.  Echoing is turned off (where possible) during the typing of your password, so it will not appear on the written record of the session. 

At some installations, an option may be invoked that will require you to enter a second “external” password.  This will occur only for dial-up connections, and will be prompted by the message “External security:”.  Both passwords are required for a successful login. 

If password aging has been invoked by the super-user on your behalf, your password may have expired.  In this case, you will be shunted into passwd(1) to change it, after which you may attempt to login again.

If you do not complete the login successfully within a certain period of time (e.g., one minute), you are likely to be silently disconnected. 

After a successful login, accounting files are updated, you will be informed of the existence (if any) of mail, and the profiles (i.e., /etc/profile and $HOME/.profile) (if any) are executed (see profile(5)). Login initializes the user and group IDs and the working directory, then executes a command interpreter (usually sh(1)) according to specifications found in the /etc/passwd file.  Argument 0 of the command interpreter is − followed by the last component of the interpreter’s path name.  The environment (see environ(7)) is initialized to:

HOME=your-login-directory
PATH=:/bin:/usr/bin
LOGNAME=your-login-name

FILES

/etc/utmpaccounting
/usr/adm/wtmpaccounting
/usr/mail/your-name mailbox for user your-name
/etc/motdmessage-of-the-day
/etc/passwdpassword file
/etc/profilesystem profile
$HOME/.profilepersonal profile

SEE ALSO

mail(1), newgrp(1), sh(1), passwd(1), su(1), passwd(5), profile(5), environ(7), getty(8). 

DIAGNOSTICS

Login incorrect
if the user name or the password is incorrect.

No shell, cannot open password file, no directory:
consult a UNIX programming counselor. 

Your password has expired. Choose a new one.
if password aging is implemented.

May 16, 1980