login(1) DG/UX 5.4.2 login(1)
NAME
login - sign on
SYNOPSIS
login [ name [ environ ... ]]
DESCRIPTION
The login command is used at the beginning of each terminal session
and allows you to identify yourself to the system. It will be
invoked by the system when a connection is first established.
If login is invoked as a command it must replace the initial command
interpreter. This is accomplished by typing
exec login
from the initial shell.
login asks for your user name (if it is not supplied as an argument),
and if appropriate, your password. Echoing is turned off (where
possible) during the typing of your password, so it will not appear
on the written record of the session.
If there are no lower-case characters in the first line of input
processed, login assumes the connecting TTY is an upper-case-only
terminal and sets the port's termio(7) options to reflect this.
If you make any mistake in the login procedure, the message
Login incorrect
is printed and a new login prompt will appear.
If you do not complete the login successfully within a certain period
of time (e.g., one minute), you are likely to be silently
disconnected.
After a successful login, accounting files are updated, the
/etc/profile script is executed, /etc/motd is printed, the user-ID,
group-ID, supplementary group list, working directory, and command
interpreter (usually sh) 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. in the working directory
is executed, if it exists. 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
path name (e.g., -sh). If this field in the password file is empty,
then the default command interpreter, /usr/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 making it the root directory. 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 is initialized to:
HOME=your-login-directory
LOGNAME=your-login-name
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login(1) DG/UX 5.4.2 login(1)
PATH=/usr/bin
SHELL=last-field-of-passwd-entry
MAIL=/var/mail/your-login-name
TZ=timezone-specification
The environment may be expanded or modified 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 in
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 which are not restricted. login
understands simple single-character quoting conventions. Typing a
backslash in front of a character quotes it and allows the inclusion
of such characters as spaces and tabs.
The system administrator can modify the behavior of login by setting
variables in the /etc/default/login file. The following variables
are available:
ALTSHELL If set to "YES" the SHELL environment variable
containing the pathname of the user's shell will be
declared as part of the basic initial environment.
CONSOLE If set, superuser login is allowed only on the terminal
specified. E.g., "CONSOLE=/dev/console" restricts
superuser login to the console. If not set, no
restrictions are placed on superuser login.
HZ Default value for the HZ (hertz) environment variable.
If not set, the value of HZ defaults to 100.
PASSREQ If set to "YES" a password is required for all non-
superusers on the system. If a new user account is
added with no password, login will prompt for a password
the first time the user attempts to log in.
PATH Default value of PATH environment variable for all non-
superuser logins on the system. If not set, the default
is "/usr/bin".
SUPATH Default value of PATH environment variable for all
superuser logins on the system. If not set, the default
is "/sbin:/usr/sbin:/usr/bin:/etc".
TIMEOUT Maximum amount of time in seconds to wait on a
successful login attempt before disconnecting. The
maximum value allowed is 900 (15 minutes). If not set,
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login(1) DG/UX 5.4.2 login(1)
timeout period defaults to 60 seconds. Setting TIMEOUT
0 disables the timeout feature.
TIMEZONE Default value for the TZ (time zone) environment
variable. If not set, the value of TZ defaults to
"EST5EDT".
ULIMIT Maximum size allowed for user files (in blocks). If
ULIMIT is not set, no file size limit is enforced.
UMASK Default umask for system users. If UMASK is not set the
default umask will be 022.
FILES
/var/adm/utmp accounting
/var/adm/wtmp accounting
/var/mail/your-name mailbox for user your-name
/etc/default/login login system-wide default settings
/etc/motd message-of-the-day
/etc/passwd password file
/etc/profile system profile
.profile user's login profile
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 a shell other
than the initial shell.
Cannot open /dev/tty.
This message appears if login is unable to open /dev/tty to read the
password.
SEE ALSO
mail(1), newgrp(1M), sh(1), su(1M).
loginlog(4), passwd(4), profile(4), environ(5).
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