login(1) C2 Trusted DG/UX 5.4.2T 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.
login asks for your user name (if it is not supplied as an argument).
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 your password has expired and you have failed to change it, the
message
Service denied
is printed, and a new login prompt appears.
If you do not complete the login successfully within a certain period
of time (normally, 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) and applicable security parameters are
initialized. These parameters are found in the Authentication and
Authorization (A&A) database entries for the user. 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. The process name
of the command interpreter is "-" followed by the last component of
the interpreter's path name (e.g., -sh).
The basic environment is initialized to:
HOME=your-login-directory
LOGNAME=your-login-name
PATH=/usr/bin
SHELL=command-interpreter-pathname
MAIL=/var/mail/your-login-name
TZ=timezone-specification
The environment may be expanded or modified by supplying additional
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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 who log 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.
HZ Default value for the HZ (hertz) environment variable.
If not set, the value of HZ defaults to 100.
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". Note that on a
Trusted system, the superuser may not login. The only
way to become the superuser is to use the su(1) command.
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,
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 077.
On a Trusted DG/UX system, agents such as ttymon or rlogind that exec
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login must supply the options -s servicename, -n locationname, and -a
locationdescription. The -s servicename option identifies the
service for which login is being invoked, and for which the user's
authorization will be checked. If -s servicename is not supplied,
login will default the service name to "", which will normally cause
the login to be refused. The -n locationname option identifies the
location from which the user is logging in. If -n locationname is
not supplied, login will default the location name to that of the tty
or pseudo-tty attached to stdin. This default is appropriate for
access to direct-connect terminals via ttymon, for example, but
inappropriate for access from a network -- knowing the pseudo-tty
name tells little or nothing about the actual location of the user.
The -a locationdescription option gives an ASCII name used to
identify the type of locationname in a syslog message whenever a
login attempt fails. If -a locationdescription is not supplied,
login failures will not be recorded in syslog.
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
0.DT
DIAGNOSTICS
Login incorrect
This is the general message that appears if the user cannot login,
e.g. when the name and the password cannot be matched.
Service denied
This message appears if your password has expired, and you have
failed to change it.
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.
If this message appears, see your system administrator.
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) in the Programmer's Reference for the DG/UX System.
Security Features User's Guide for the Trusted DG/UX System
Trusted Facility Manual for the C2 Trusted DG/UX System
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