login(1) [osx man page]

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

NAME

     login -- log into the computer

SYNOPSIS

     login [-pq] [-h hostname] [user]
     login -f [-lpq] [-h hostname] [user [prog [args...]]]

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 configurable via pam(8).	Password authentication is the default.

     The following options are available:

     -f      When a user name is specified, this option indicates 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.

	     With the -f option, an alternate program (and any arguments) may be run instead of the user's default shell.  The program and argu-
	     ments follows the user name.

     -h      Specify 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.

     -l      Tells the program executed by login that this is not a login session (by convention, a login session is signalled to the program with
	     a hyphen as the first character of argv[0]; this option disables that), and prevents it from chdir(2)ing to the user's home direc-
	     tory.  The default is to add the hyphen (this is a login session).

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

     -q      This forces quiet logins, as if a .hushlogin is present.

     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.  -q
     is specified, 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 utmpx(5) and the like, and executes the user's command interpreter (or the program specified on the command line if -f is speci-
     fied).

     The login utility 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).

     Some shells may provide a builtin login command which is similar or identical to this utility.  Consult the builtin(1) manual page.

     The login utility will submit an audit record when login succeeds or fails.  Failure to determine the current auditing state will result in
     an error exit from login.

FILES

     /etc/motd		message-of-the-day
     /etc/nologin	disallows logins
     /var/run/utmpx	current logins
     /var/mail/user	system mailboxes
     .hushlogin 	makes login quieter
     /etc/pam.d/login	pam(8) configuration file
     /etc/security/audit_user
			user flags for auditing
     /etc/security/audit_control
			global flags for auditing

SEE ALSO

     builtin(1), chpass(1), newgrp(1), passwd(1), rlogin(1), getpass(3), utmpx(5), environ(7)

HISTORY

     A login utility appeared in Version 6 AT&T UNIX.

BSD
								September 13, 2006							       BSD

SU(1)							    BSD General Commands Manual 						     SU(1)

NAME

     su -- substitute user identity

SYNOPSIS

     su [-] [-flm] [login [args]]

DESCRIPTION

     The su utility requests appropriate user credentials via PAM and switches to that user ID (the default user is the superuser).  A shell is
     then executed.

     PAM is used to set the policy su(1) will use.  In particular, by default only users in the ``admin'' or ``wheel'' groups can switch to UID 0
     (``root'').  This group requirement may be changed by modifying the ``pam_group'' section of /etc/pam.d/su.  See pam_group(8) for details on
     how to modify this setting.

     By default, the environment is unmodified with the exception of USER, HOME, and SHELL.  HOME and SHELL are set to the target login's default
     values.  USER is set to the target login, unless the target login has a user ID of 0, in which case it is unmodified.  The invoked shell is
     the one belonging to the target login.  This is the traditional behavior of su.

     The options are as follows:

     -f      If the invoked shell is csh(1), this option prevents it from reading the ``.cshrc'' file.

     -l      Simulate a full login.  The environment is discarded except for HOME, SHELL, PATH, TERM, and USER.  HOME and SHELL are modified as
	     above.  USER is set to the target login.  PATH is set to ``/bin:/usr/bin''.  TERM is imported from your current environment.  The
	     invoked shell is the target login's, and su will change directory to the target login's home directory.

     -	     (no letter) The same as -l.

     -m      Leave the environment unmodified.	The invoked shell is your login shell, and no directory changes are made.  As a security precau-
	     tion, if the target user's shell is a non-standard shell (as defined by getusershell(3)) and the caller's real uid is non-zero, su
	     will fail.

     The -l (or -) and -m options are mutually exclusive; the last one specified overrides any previous ones.

     If the optional args are provided on the command line, they are passed to the login shell of the target login.  Note that all command line
     arguments before the target login name are processed by su itself, everything after the target login name gets passed to the login shell.

     By default (unless the prompt is reset by a startup file) the super-user prompt is set to ``#'' to remind one of its awesome power.

ENVIRONMENT

     Environment variables used by su:

     HOME  Default home directory of real user ID unless modified as specified above.

     PATH  Default search path of real user ID unless modified as specified above.

     TERM  Provides terminal type which may be retained for the substituted user ID.

     USER  The user ID is always the effective ID (the target user ID) after an su unless the user ID is 0 (root).

FILES

     /etc/pam.d/su  PAM configuration for su.

EXAMPLES

     su man -c catman
	    Runs the command catman as user man.  You will be asked for man's password unless your real UID is 0.
     su man -c 'catman /usr/share/man /usr/local/man'
	    Same as above, but the target command consists of more than a single word and hence is quoted for use with the -c option being passed
	    to the shell.  (Most shells expect the argument to -c to be a single word).
     su -l foo
	    Simulate a login for user foo.
     su - foo
	    Same as above.
     su -   Simulate a login for root.

SEE ALSO

     csh(1), sh(1), group(5), passwd(5), environ(7), pam_group(8)

HISTORY

     A su command appeared in Version 1 AT&T UNIX.

BSD
								September 13, 2006							       BSD