login(1) [opendarwin man page]

LOGIN(1)						    BSD General Commands Manual 						  LOGIN(1)

NAME

     login -- log into the computer

SYNOPSIS

     login [-fp] [-h hostname] [user]

DESCRIPTION

     The login utility logs users (and pseudo-users) into the computer system.

     If no user is specified, or if a user is specified and authentication of the user fails, login prompts for a user name.  Authentication of
     users is done via passwords.

     The options are as follows:

     -f      The -f option is used when a user name is specified to indicate that proper authentication has already been done and that no password
	     need be requested.  This option may only be used by the super-user or when an already logged in user is logging in as themselves.

     -h      The -h option specifies the host from which the connection was received.  It is used by various daemons such as telnetd(8).  This
	     option may only be used by the super-user.

     -p      By default, login discards any previous environment.  The -p option disables this behavior.

     If the file /etc/nologin exists, login dislays its contents to the user and exits.  This is used by shutdown(8) to prevent users from logging
     in when the system is about to go down.

     Immediately after logging a user in, login displays the system copyright notice, the date and time the user last logged in, the message of
     the day as well as other information.  If the file ``.hushlogin'' exists in the user's home directory, all of these messages are suppressed.
     This is to simplify logins for non-human users, such as uucp(1).  Login then records an entry in the wtmp(5) and utmp(5) files and executes
     the user's command interpreter.

     Login enters information into the environment (see environ(7)) specifying the user's home directory (HOME), command interpreter (SHELL),
     search path (PATH), terminal type (TERM) and user name (both LOGNAME and USER).

     The standard shells, csh(1) and sh(1), do not fork before executing the login utility.

FILES

     /etc/motd		message-of-the-day
     /etc/nologin	disallows logins
     /var/run/utmp	current logins
     /var/log/lastlog	last login account records
     /var/log/wtmp	login account records
     /var/mail/user	system mailboxes
     .hushlogin 	makes login quieter

SEE ALSO

     chpass(1), passwd(1), rlogin(1), getpass(3), utmp(5), environ(7),

HISTORY

     A login appeared in Version 6 AT&T UNIX.

4th Berkeley Distribution					    May 5, 1994 					 4th Berkeley Distribution

UTMP(5) 						      BSD File Formats Manual							   UTMP(5)

NAME

     utmp, wtmp, lastlog -- login records (DEPRECATED)

SYNOPSIS

     #include <utmp.h>

DESCRIPTION

     The interfaces in file <utmp.h> are all DEPRECATED and are only provided for compatibility with previous releases of Mac OS X.  See
     pututxline(3) and utmpx(5) for the supported interfaces.

     <utmp.h> declares the structures used to record information about current users in the file utmp, logins and logouts in the file wtmp, and
     last logins in the file lastlog.  The time stamps of date changes, shutdowns and reboots are also logged in the wtmp file.

     These files can grow rapidly on busy systems, daily or weekly rotation is recommended.  If any of these files do not exist, it is not cre-
     ated.  These files must be created manually and are normally maintained in either the script /etc/daily or the script /etc/weekly.  (See
     cron(8).)

	   #define _PATH_UTMP	   "/var/run/utmp"
	   #define _PATH_WTMP	   "/var/log/wtmp"
	   #define _PATH_LASTLOG   "/var/log/lastlog"

	   #define UT_NAMESIZE	   8
	   #define UT_LINESIZE	   8
	   #define UT_HOSTSIZE	   16

	   struct lastlog {
		   time_t  ll_time;
		   char    ll_line[UT_LINESIZE];
		   char    ll_host[UT_HOSTSIZE];
	   };

	   struct utmp {
		   char    ut_line[UT_LINESIZE];
		   char    ut_name[UT_NAMESIZE];
		   char    ut_host[UT_HOSTSIZE];
		   time_t  ut_time;
	   };

     Each time a user logs in, the login program looks up the user's UID in the file lastlog. If it is found, the timestamp of the last time the
     user logged in, the terminal line and the hostname are written to the standard output. (Providing the login is not quiet, see login(1).)  The
     login program then records the new login time in the file lastlog.

     After the new lastlog record is written , the file utmp is opened and the utmp record for the user inserted.  This record remains there until
     the user logs out at which time it is deleted.  The utmp file is used by the programs rwho(1), users(1), w(1), and who(1).

     Next, the login program opens the file wtmp, and appends the user's utmp record.  The same utmp record, with an updated time stamp is later
     appended to the file when the user logs out. (See launchd(8).)  The wtmp file is used by the programs last(1) and ac(8).

     In the event of a date change, a shutdown or reboot, the following items are logged in the wtmp file.

     reboot
     shutdown	 A system reboot or shutdown has been initiated.  The character '~' is placed in the field ut_line, and reboot or shutdown in the
		 field ut_name.  (See shutdown(8) and reboot(8).)

     date	 The system time has been manually or automatically updated.  (See date(1).)  The command name date is recorded in the field
		 ut_name.  In the field ut_line, the character '|' indicates the time prior to the change, and the character '{' indicates the new
		 time.

FILES

     (These files no longer exist in 10.5 or later.)

     /var/run/utmp     The utmp file.
     /var/log/wtmp     The wtmp file.
     /var/log/lastlog  The lastlog file.

SEE ALSO

     last(1), login(1), who(1), ac(8), launchd(8)

HISTORY

     A utmp and wtmp file format appeared in Version 6 AT&T UNIX.  The lastlog file format appeared in 3.0BSD.

4th Berkeley Distribution					  March 17, 1994					 4th Berkeley Distribution