login(1)
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login Command
sign on
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SYNTAX
login [ name [ env-var ... ]]
DESCRIPTION
The login command identifies you to the system. Generally, the
system is already running login when you first approach it. An
unoccupied terminal will be displaying
Login:
Type your username, then press NEW LINE. The system then
displays:
Password:
You type your password (it will not show on the screen). The
system will check your name and password, and either tell you to
try again (if an answer was wrong) or proceed to log you in.
When you log out (by typing Control-D at the command line
prompt), the system prepares for the next user by running the
login program, showing the login: prompt on the screen.
If you invoke login from the command line, it must replace the
initial command interpreter. Type "exec login" from the initial
shell.
Login asks for your user name (if not supplied as an argument),
and, if appropriate, your password. Echoing is turned off (where
possible) while you type your password, so it will not appear on
the written record of the session.
At some installations, an option may be invoked that will require
you to enter a second ``dialup'' password. This will occur only
for dial-up connections, and will be prompted by the message
"dialup password:". Both passwords are required.
If you do not complete the login successfully within one minute,
you are likely to be silently disconnected.
After a successful login, accounting files are updated and the
user ID, group ID, working directory, and command interpreter
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login(1)
(usually sh(1)) are initialized. If the initialized command
interpreter is sh, login instructs sh to perform the procedure
/etc/profile. In addition, if the file .profile exists in the
working directory, sh executes it as well. These specifications
are found in the /etc/passwd file entry for the user. The name
of the command interpreter is - followed by the last component of
the interpreter's pathname (i.e., -sh). If this field in the
password file is empty, then the default command interpreter
/bin/sh is used. If this field is *, then a chroot(2) is done to
the directory named in the directory field of the entry. At that
point login is re-executed at the new level which must have its
own root structure, including /etc/login and /etc/passwd.
The basic environment (see environ(5)) is initialized to:
HOME=your-login-directory
PATH=:/bin:/usr/bin
SHELL=last-field-of-passwd-entry
MAIL=/usr/mail/your-login-name
TZ=timezone-specification
You can change the environment by supplying additional arguments
to login, either at execution time or when login requests your
login name. The arguments may take either the form xxx or
xxx=yyy. Arguments without an equal sign are placed in the
environment as
Ln=xxx
where n is a number starting at 0 and is incremented each time a
new variable name is required. Variables containing an = are
placed into the environment without modification. If they
already appear in the environment, then they replace the older
value. There are two exceptions. The variables PATH and SHELL
cannot be changed. This prevents people, logging into restricted
shell environments, from spawning secondary shells that are not
restricted. Both login and getty understand simple single-
character enquoting conventions. Typing a backslash in front of
a character quotes it and lets you include such things as spaces
and tabs.
FILES
/etc/utmp Accounting
/etc/wtmp Accounting
/usr/mail/your-name Mailbox for user your-name
/etc/motd Message-of-the-day
/etc/passwd Password file
/etc/profile System profile
.profile User's login profile
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login(1)
SEE ALSO
mail(1), newgrp(1), sh(1), su(1).
passwd(4), profile(4), environ(5) in the Programmer's Reference
for the DG/UX System
DIAGNOSTICS
login incorrect
This message appears if the user name or the password cannot be
matched.
No shell, cannot open password file, or no directory
If these messages appear consult your system administrator.
No utmp entry. You must exec login from the lowest level sh.
This message appears if you attempted to execute login as a
command without using the shell's exec internal command or from
other than the initial shell.
Cannot open /dev/tty.
This message appears if login is unable to open /dev/tty to read
the password.
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