login —
log into the computer
login |
[ -fp
]
[-h
hostname
]
[-L
local-addr
]
[-R
remote-addr
]
[-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.
-
-
-h
hostname- Specifies the host from which the connection was received. This option may
only be used by the superuser.
-
-
-L
local-addr- The
-L option specifies the local
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 option disables
this behavior.
-
-
-R
remote-addr- The
-R option specifies the remote
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 option 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.
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 database.
-
-
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.
-
-
MAIL- The user's mailbox.
-
-
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/log/failedlogin
- failed login account records
- /var/log/lastlog
- last login account records
- /var/log/wtmp
- login account records
- /var/mail/user
- system mailboxes
- /var/run/utmp
- current logins
- .hushlogin
- makes login quieter
chpass(1),
passwd(1),
su(1),
telnet(1),
readpassphrase(3),
setusercontext(3),
fbtab(5),
login.conf(5),
utmp(5),
environ(7)
A
login utility appeared in
Version 3 AT&T UNIX.
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