LOGIN(1) General Commands Manual LOGIN(1)
login - log in to the system
login [ -p ] [ username ]
login signs username on to the system initially; login may also be used
at any time to change from one user ID to another.
When used with no argument, login requests a user name and password (if
appropriate). Echoing is turned off (if possible) while typing the
password. Note: the number of significant characters in a password is
8. See passwd(1).
If password aging is enabled and the password corresponding to the user
name has expired, the user will be prompted for a new password. The
user has to successfully modify his password for login to proceed. See
When successful, login updates accounting files, prints disk usage and
limits (by running quota(1),) prints the message of the day, informs
you of the existence of any mail, and displays the time you last logged
in. None of these messages is printed if there is a .hushlogin file in
your home directory. This is mostly used to make life easier for non-
human users, such as uucp(1C).
login initializes the user and group IDs and the working directory,
then starts a command interpreter shell (usually either sh(1) or
csh(1)) according to specifications found in the file /etc/passwd.
Argument 0 of the command interpreter is the name of the command inter-
preter with a leading dash (`-') prepended.
login also modifies the environment (environ(5V)) with information
specifying home directory, command interpreter, terminal-type (if
available) and username. The -p argument preserves the remainder of
the environment, otherwise any previous environment is discarded.
The super-user root may only log in on those terminals marked as
"secure" in the /etc/ttytab file. Otherwise, the super-user must log
in as an ordinary user and become super-user using su(1v). For exam-
ple, if the file contained:
console "/etc/getty Console-9600" sun on secure
tty00 "/etc/getty Console-9600" sun on
the super-user could only log in directly on the console. See
ttytab(5) for a discussion of "secure" and other getty(8) options used
If the file /etc/nologin exists, login prints its contents on the
user's terminal and exits. This is used by shutdown(8) to stop logins
when the system is about to go down.
The login command, recognized by sh(1) and csh(1), is executed directly
(without forking), and terminates that shell. To resume working, you
must log in again.
login times out and exits if its prompt for input is not answered
within a reasonable time.
When the Bourne shell (sh) starts up, it reads a file called .profile
from your home directory (that of the username you use to log in).
When the C shell (csh) starts up, it reads a file called .cshrc from
your home directory, and then reads a file called .login.
The shells read these files only if they are owned by the person log-
-p Preserve any existing environment variables and their values;
otherwise the previous environment is discarded.
/var/adm/lastlog time of last login
/etc/ttytab terminal types
/usr/ucb/quota quota check
/etc/passwd password file
/etc/nologin stop login, print message
~/.hushlogin makes login quieter
csh(1), mail(1), passwd(1), quota(1), rlogin(1C), sh(1), uucp(1C), env-
iron(5V), fbtab(5), passwd(5), svdtab(5), utmp(5V), getty(8), init(8),
Login incorrect If the name or the password is bad (or mistyped).
cannot open password file
no directory Ask your system administrator for assistance.
The following options are undocumented, and not intended for the user.
The -r option is used by the remote login server, rlogind(8C) to force
login to enter into an initial connection protocol. -h is used by tel-
netd(8C) and other servers to list the host from which the connection
The following warnings apply when login account names contain charac-
ters outside the range of 7-bit ASCII:
o A user cannot rlogin to account-name containing 8-bit characters
from a system that does not handle 8-bit characters.
o A user cannot log in to account-name containing 8-bit characters
from a 7-bit ASCII terminal (through a modem, for example).
o Several parts of the C library are not tested for 8-bit user names.
o Codeset mapping can vary between systems, so an 8-bit pattern can
represent different characters on different sytems.
o Password algorithms do not work with 8-bit characters in the pass-
12 June 1988 LOGIN(1)