login(1) General Commands Manual login(1)
login - Signs the user on to the system
login [-p] [-h host] [[-f] user]
The login command is used when a user initially signs on to the system and also by daemons, such as ftp, to create a user's environment.
This security-sensitive command uses the Security Integration Architecture (SIA) routine as an interface to the security mechanism(s) that
perform the actual user validation. See the matrix.conf(4) reference page for more information.
With the exception of -p, these options are available only to the superuser. Used by telnetd and other servers to list the host from which
the connection was received. Used with a user name user on the command line to indicate that proper authentication was already done, and
that no password needs to be requested. Causes the remainder of the environment to be preserved; otherwise, any previous environment is
The invocation of login for initial signon is made by a system program or server using the privileged -h and -f forms of the login command.
If login is invoked without an argument, it asks for a user name, and, if appropriate, a password. Echoing is turned off (if possible)
during the entering of the password, so it will not appear on the written record of the session.
After a successful login, accounting files are updated. You are informed of the existence of mail, and the message of the day and the time
of last login are displayed. The mail message, the message of the day, and the last login time are suppressed if there is a file in the
home directory; this is mostly used to make life easier for users such as uucp.
If you have enhanced security installed on your system, the login command prints the last successful and unsuccessful login times and ter-
minal devices. If the account does not have a password and the authentication profile for the account requires one, login starts the
passwd command to establish one for the account.
The login command prohibits you from logging in if any of the following are true: The password for the account has expired and you cannot
successfully change the password. The password lifetime for the account has passed. The administrative lock on the account was set. The
maximum number of unsuccessful login attempts for the account was exceeded. The maximum number of unsuccessful login attempts for the ter-
minal was exceeded. The administrative lock on the terminal was set. The terminal has an authorized user list and you are not on it. The
terminal has time of day restrictions and the current time is not within them. The account was retired by the system administrator.
The login command initializes the user and group IDs and the working directory, and then executes a command interpreter according to spec-
ifications found in the password file. Argument 0 (zero) of the command interpreter is the name of the command interpreter with a leading -
The login command also modifies the environment with information specifying home directory, command interpreter, terminal type (if avail-
able), and user name.
If you have enhanced security installed on your system, the login command always allows root to log in at the console to avoid the situa-
tion where all accounts and terminals are locked.
If either /etc/nologin_hostname or /etc/nologin exists, login prints the contents on your terminal and exits. The shutdown command creates
/etc/nologin_hostname (or /etc/nologin in the case of a clusterwide shutdown) to stop users from logging in when the system or cluster is
about to go down.
Login is recognized by sh, csh, and ksh and executed directly (without forking).
The user name or the password is invalid. Consult your system administrator.
If you have enhanced security installed on your system, you may see the following diagnostic messages: The login command cannot
invoke the passwd program. The passwd program is invoked, the user is unable to change the password, and the account requires one.
The login command is allowing a root login at the system console, despite a condition that would normally not allow such a login.
The account is locked for one of the reasons previously listed. The terminal is locked for one of the reasons previously listed.
You are not on the authorized user list for the terminal. The current time is not within the current time-of-day restrictions for
After an unsuccessful login attempt, login waits a specified (configurable) amount of time before it prompts for another login
If the account's password was changed by another user, login prints the time the password was changed and the user who changed it.
If your password is about to expire, login warns you of the time of the impending expiration. Your system administrator sets the
Contains user and accounting information. Contains login history. Contains last login time stamps. Mail directory. Message of the day.
Contains user information. Stops logins. In a cluster, /etc/nologin is used instead. Suppresses mail notification, message of the day,
and last login time.
Commands: binmail(1), chfn(1), chsh(1), getty(8), init(8), Mail(1), mail(1), mailx(1), passwd(1), rlogin(1), shutdown(8)
Files: matrix.conf(4), passwd(4), utmp(4)