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LOGIN(1)                    General Commands Manual                   LOGIN(1)



NAME
       login - log in to the system

SYNOPSIS
       login [ -p ] [ username ]

DESCRIPTION
       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
       passwd(1).

       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
       in /etc/ttytab.

       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-
       ging in.

OPTIONS
       -p     Preserve any existing environment variables  and  their  values;
              otherwise the previous environment is discarded.

FILES
       /etc/utmp           accounting
       /var/adm/wtmp       accounting
       /var/adm/lastlog    time of last login
       /etc/ttytab         terminal types
       /usr/ucb/quota      quota check
       /var/spool/mail/*   mail
       /etc/motd           message-of-the-day
       /etc/passwd         password file
       /etc/nologin        stop login, print message
       ~/.hushlogin        makes login quieter
       .login
       .profile

SEE ALSO
       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),
       shutdown(8)

DIAGNOSTICS
       Login incorrect     If the name or the password is bad (or mistyped).

       No Shell

       cannot open password file

       no directory        Ask your system administrator for assistance.

NOTES
       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
       was received.

       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-
          word.



                                 12 June 1988                         LOGIN(1)