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SU(1)				 User Commands				 SU(1)

       su - run a command with substitute user and group ID

       su [options...] [-] [user [args...]]

       su allows to run commands with substitute user and group ID.

       When  called  without  arguments	 su defaults to running an interactive
       shell as root.

       For backward compatibility su defaults to not change the current direc-
       tory  and  to  only  set the environment variables HOME and SHELL (plus
       USER and LOGNAME if the target user is not root).  It is recommended to
       always  use  the --login option (instead it's shortcut -) to avoid side
       effects caused by mixing environments.

       This version of su uses PAM for	authentication,	 account  and  session
       management.   Some  configuration options found in other su implementa-
       tions such as e.g. support of a wheel group have to be  configured  via

       -c command, --command=command
	      Pass command to the shell with the -c option.

	      Same as -c but do not create a new session (discouraged).

       -f, --fast
	      Pass -f to the shell which may or may not be useful depending on
	      the shell.

       -g, --group=group
	      specify the primary group, this option is allowed for root  user

       -G, --supp-group=group
	      specify  a  supplemental	group, this option is allowed for root
	      user only

       -, -l, --login
	      Starts the shell as login shell with an environment similar to a
	      real login:

		 o	clears all environment variables except for TERM

		 o	initializes  the  environment  variables  HOME, SHELL,

		 o	changes to the target user's home directory

		 o	sets argv[0] of the shell to '-' in order to make  the
			shell a login shell

       -m, -p, --preserve-environment
	      Preserves	 the  whole  environment, ie does not set HOME, SHELL,
	      USER nor LOGNAME.	 The option is ignored if the  option  --login
	      is specified.

       -s SHELL, --shell=SHELL
	      Runs  the	 specified shell instead of the default.  The shell to
	      run is selected according to the following rules in order:

		 o	the shell specified with --shell

		 o	The shell specified in the environment variable	 SHELL
			if the --preserve-environment option is used.

		 o	the  shell  listed  in	the passwd entry of the target

		 o	/bin/sh

	      If the target user has a restricted shell (i.e.  not  listed  in
	      /etc/shells)  the --shell option and the SHELL environment vari-
	      ables are ignored unless the calling user is root.

       --help Display help text and exit.

	      Display version information and exit.

       su reads the /etc/default/su and /etc/login.defs	 configuration	files.
       The following configuration items are relevant for su(1):

       FAIL_DELAY (number)
	   Delay in seconds in case of authentication failure.	Number must be
	   a non-negative integer.

       ENV_PATH (string)
	   Defines the PATH environment variable  for  a  regular  user.   The
	   default value is /usr/local/bin:/bin:/usr/bin.

       ENV_ROOTPATH (string)
       ENV_SUPATH (string)
	   Defines  the	 PATH environment variable for root. The default value
	   is /usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin.

       ALWAYS_SET_PATH (boolean)
	   If set to yes and --login and --preserve-environment were not spec-
	   ified su initializes PATH.

       su normally returns the exit status of the command it executed.	If the
       command was killed by a signal, su returns the  number  of  the	signal
       plus 128.

       Exit status generated by su itself:

		 1	Generic error before executing the requested command

		 126	The requested command could not be executed

		 127	The requested command could was not found

       /etc/pam.d/su	default PAM configuration file
       /etc/pam.d/su-l	PAM configuration file if --login is specified
       /etc/default/su	command specific logindef config file
       /etc/login.defs	global logindef config file

       runuser(8), pam(8), shells(5), login.defs(5)

       Derived	from  coreutils'  su which was based on an implementation from
       David MacKenzie.

       The su command is part of the util-linux package and is available  from
       Linux	Kernel	 Archive   <ftp://ftp.kernel.org/pub/linux/utils/util-

util-linux			   June 2012				 SU(1)