LOGIN(1) UNIX Programmer's Manual LOGIN(1)
S
\bSY
\bYN
\bNO
\bOP
\bPS
\bSI
\bIS
\bS
l
\blo
\bog
\bgi
\bin
\bn [ -
\b-p
\bp ] [ username ]
l
\blo
\bog
\bgi
\bin
\bn [ -
\b-p
\bp ] [ -
\b-h
\bh hostname ] [ -
\b-f
\bf ] [ username ]
D
\bDE
\bES
\bSC
\bCR
\bRI
\bIP
\bPT
\bTI
\bIO
\bON
\bN
The _
\bl_
\bo_
\bg_
\bi_
\bn command is used when a user initially signs on.
It may also be used at any time to change from one user to
another. This case is the one summarized first above and
described here. See "How to Get Started" for how to connect
initially. The invocation of _
\bl_
\bo_
\bg_
\bi_
\bn for initial sign-on is
made by a system program or server using the latter form of
the command and is described below.
If _
\bl_
\bo_
\bg_
\bi_
\bn is invoked without an argument, it asks for a user
name, and, if appropriate, a password. Echoing is turned
off (if possible) during the typing of the password, so it
will not appear on the written record of the session.
After a successful login, accounting files are updated and
the user is informed of the existence of mail. The message
of the day is printed, as is the time of his last login.
Both are suppressed if he has a ".hushlogin" file in his
home directory; this is mostly used to make life easier for
non-human users, such as _
\bu_
\bu_
\bc_
\bp.
_
\bL_
\bo_
\bg_
\bi_
\bn initializes the user and group IDs and the working
directory, then executes a command interpreter (usually
_
\bc_
\bs_
\bh(1)) according to specifications found in a password
file. Argument 0 of the command interpreter is the name of
the command interpreter with a leading dash ("-").
Login also modifies the environment _
\be_
\bn_
\bv_
\bi_
\br_
\bo_
\bn(7) with informa-
tion specifying home directory, command interpreter, termi-
nal type (if available) and user name. The `-p' argument
causes the remainder of the environment to be preserved,
otherwise any previous environment is discarded.
If the file /etc/nologin exists, _
\bl_
\bo_
\bg_
\bi_
\bn prints its contents
on the user's terminal and exits. This is used by _
\bs_
\bh_
\bu_
\bt_
\b-
_
\bd_
\bo_
\bw_
\bn(8) to stop users logging in when the system is about to
Login is recognized by _
\bs_
\bh(1) and _
\bc_
\bs_
\bh(1) and executed
directly (without forking).
There are several additional options to _
\bl_
\bo_
\bg_
\bi_
\bn for use at
initial login. With one exception, these options are avail-
able only to the superuser. The -
\b-h
\bh option is used by
_
\bt_
\be_
\bl_
\bn_
\be_
\bt_
\bd(8C) and other servers to list the host from which
Printed 7/9/88 September 14, 1987 1
LOGIN(1) UNIX Programmer's Manual LOGIN(1)
the connection was received. The -
\b-f
\bf option is used with a
username on the command line to indicate that proper authen-
tication has already been done and that no password need be
requested. This option may be used by the superuser or by
the user specified on the command line.
/etc/motd message-of-the-day
/etc/passwd password file
/etc/nologin stops logins
.hushlogin makes login quieter
S
\bSE
\bEE
\bE A
\bAL
\bLS
\bSO
\bO
mail(1), passwd(1), rlogin(1), getpass(3), passwd(5),
utmp(5), environ(7), init(8), getty(8), shutdown(8),
D
\bDI
\bIA
\bAG
\bGN
\bNO
\bOS
\bST
\bTI
\bIC
\bCS
\bS
"Login incorrect," if the name or the password is bad.
"No Shell", "cannot open password file", "no directory":
consult a programming counselor.
An undocumented option, -
\b-r
\br is used by the remote login
server, _
\br_
\bl_
\bo_
\bg_
\bi_
\bn_
\bd(8) to force _
\bl_
\bo_
\bg_
\bi_
\bn to enter into an initial
Printed 7/9/88 September 14, 1987 2
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