xref: /freebsd/usr.bin/login/login.1 (revision bdcbfde31e8e9b343f113a1956384bdf30d1ed62)

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.Dd September 29, 2022
.Dt LOGIN 1
.Os
.Sh NAME
.Nm login
.Nd log into the computer
.Sh SYNOPSIS
.Nm
.Op Fl fp
.Op Fl h Ar hostname
.Op Ar user
.Sh DESCRIPTION
The
.Nm
utility logs users (and pseudo-users) into the computer system.
.Pp
If no user is specified, or if a user is specified and authentication
of the user fails,
.Nm
prompts for a user name.
Authentication of users is configurable via
.Xr pam 8 .
Password authentication is the default.
.Pp
The following options are available:
.Bl -tag -width indent
.It Fl f
When a user name is specified, this option indicates that proper
authentication has already been done and that no password need be
requested.
This option may only be used by the super-user or when an already
logged in user is logging in as themselves.
.It Fl h
Specify the host from which the connection was received.
It is used by various daemons such as
.Nm telnetd .
This option may only be used by the super-user.
.It Fl p
By default,
.Nm
discards any previous environment.
The
.Fl p
option disables this behavior.
.El
.Pp
Login access can be controlled via
.Xr login.access 5
or the login class in
.Xr login.conf 5 ,
which provides
allow and deny records based on time, tty and remote host name.
.Pp
If the file
.Pa /etc/fbtab
exists,
.Nm
changes the protection and ownership of certain devices specified in this
file.
.Pp
Immediately after logging a user in,
.Nm
displays the system copyright notice, the date and time the user last
logged in, the message of the day as well as other information.
If the file
.Pa .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
.Xr uucp 1 .
.Pp
The
.Nm
utility enters information into the environment (see
.Xr 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).
Other environment variables may be set due to entries in the login
class capabilities database, for the login class assigned in the
user's system passwd record.
The login class also controls the maximum and current process resource
limits granted to a login, process priorities and many other aspects of
a user's login environment.
.Pp
Some shells may provide a builtin
.Nm
command which is similar or identical to this utility.
Consult the
.Xr builtin 1
manual page.
.Pp
The
.Nm
utility will submit an audit record when login succeeds or fails.
Failure to determine the current auditing state will
result in an error exit from
.Nm .
.Sh FILES
.Bl -tag -width ".Pa /etc/security/audit_control" -compact
.It Pa /etc/fbtab
changes device protections
.It Pa /etc/login.conf
login class capabilities database
.It Pa /var/run/motd
message-of-the-day
.It Pa /var/mail/user
system mailboxes
.It Pa \&.hushlogin
makes login quieter
.It Pa /etc/pam.d/login
.Xr pam 8
configuration file
.It Pa /etc/security/audit_user
user flags for auditing
.It Pa /etc/security/audit_control
global flags for auditing
.El
.Sh SEE ALSO
.Xr builtin 1 ,
.Xr chpass 1 ,
.Xr csh 1 ,
.Xr newgrp 1 ,
.Xr passwd 1 ,
.Xr rlogin 1 ,
.Xr getpass 3 ,
.Xr fbtab 5 ,
.Xr login.access 5 ,
.Xr login.conf 5 ,
.Xr environ 7
.Sh HISTORY
A
.Nm
utility appeared in
.At v6 .