LOGIN(1) BSD Reference Manual LOGIN(1)
login - log into the computer
login [-fp] [-h hostname] [-L local-ip-address] [-R remote-ip-address]
[-u username] [user]
The login utility logs users (and pseudo-users) into the computer system.
If no user is specified, or if a user is specified and authentication of
the user fails, login prompts for a user name. Authentication of users is
normally done via passwords, though external authentication mechanisms
may be used (see login.conf(5)). To specify the alternate authentication
mechanism style, the string :style is appended to the user name (i.e.,
user:style).
The options are as follows:
-f The -f option is used when a user name is specified to indicate
that proper authentication has already been done and that no
password need be requested. This option may only be used by the
superuser or when an already logged in user is logging in as
themselves.
-h hostname
Specifies the host from which the connection was received. This
option may only be used by the superuser.
-L The -L option specifies the local IP address of a socket. This
information is passed on to any classify script (see
login.conf(5)).
-p By default, login discards any previous environment. The -p op-
tion disables this behavior.
-R The -R option specifies the remote IP address of a socket. This
information is passed on to any classify script (see
login.conf(5)).
-u username
Specifies the remote user that initiated the connection. This op-
tion may only be used by the superuser.
If the file /etc/nologin exists (and the "ignorenologin" boolean is not
set in the user's login class), login displays its contents to the user
and exits. This is used by shutdown(8) to prevent users from logging in
when the system is about to go down.
If the file /etc/fbtab exists, login changes the protection and ownership
of certain devices specified in this file.
If the file /var/log/failedlogin exists, login will record failed login
attempts in this file.
Immediately after logging a user in, login displays the system copyright
notice, the date and time the user last logged in, the date and time of
the last unsuccessful login (if the file /var/log/failedlogin exists),
the message of the day as well as other information. If the file
".hushlogin" exists in the user's home directory, all of these messages
are suppressed. This is to simplify logins for non-human users, such as
uucp. login then records an entry in the wtmp(5) and utmp(5) files and
executes the user's command interpreter.
login enters information into the environment (see environ(7)) specifying
the user's home directory (HOME), command interpreter (SHELL), search
path (PATH), terminal type (TERM), and user name (both LOGNAME and USER).
The standard shells, csh(1) and sh(1), do not fork before executing the
login utility.
Note that if login is invoked by a non-root user, it will execute su(1)
in login emulation mode instead.
login sets the following environment variables:
HOME The user's home directory, as specified by the password data-
base.
SHELL The user's shell, as specified by the password database.
TERM The user's terminal type, if it can be determined.
LOGNAME The user's login name.
USER Same as LOGNAME.
REMOTEHOST The name of the host from which the user logged in, if the -h
flag was specified.
REMOTEUSER The name of the remote user who initiated the connection, if
the -u flag was specified.
Other environment variables may be specified in /etc/login.conf via the
"setenv" capability.
/etc/fbtab changes device protections
/etc/login.conf login configuration
/etc/motd message-of-the-day
/etc/nologin disallows logins
/var/run/utmp current logins
/var/log/failedlogin failed login account records
/var/log/lastlog last login account records
/var/log/wtmp login account records
/var/mail/user system mailboxes
.hushlogin makes login quieter
chpass(1), passwd(1), su(1), telnet(1), getpass(3), setusercontext(3),
fbtab(5), login.conf(5), utmp(5), environ(7)
A login utility appeared in Version 3 AT&T UNIX.
MirBSD #10-current May 5, 1994 1