[apple/shell_cmds.git] / su / su.1

.\" Copyright (c) 1988, 1990, 1993, 1994
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"	from: @(#)su.1	8.2 (Berkeley) 4/18/94
.\"	$NetBSD: su.1,v 1.14 1997/10/19 23:31:52 lukem Exp $
.\"
.Dd April 18, 1994
.Dt SU 1
.Os
.Sh NAME
.Nm su
.Nd substitute user identity
.Sh SYNOPSIS
.Nm
.Op Fl flm
.Op Ar login 
.Op Ar -c shell arguments
.Sh DESCRIPTION
.Nm
requests the password for
.Ar login
and switches to
that user and group ID after obtaining proper authentication.
A shell is then executed, and any additional
.Ar "shell arguments"
after the login name
are passed to the shell.
If
.Nm
is executed by root, no password is requested and a shell
with the appropriate user ID is executed.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl c
Invoke the following command in a subshell as the specified user.
.It Fl f
If the invoked shell is
.Xr csh 1 ,
this option prevents it from reading the
.Dq Pa .cshrc
file.
.It Fl l
Simulate a full login.
The environment is discarded except for
.Ev HOME ,
.Ev SHELL ,
.Ev PATH ,
.Ev TERM ,
and
.Ev USER .
.Ev HOME
and
.Ev SHELL
are modified as above.
.Ev USER
is set to the target login.
.Ev PATH
is set to
.Dq Pa /bin:/usr/bin .
.Ev TERM
is imported from your current environment.
The invoked shell is the target login's, and
.Nm
will change directory to the target login's home directory.
This option is identical to just passing "-", as in "su -".
.It Fl m
Leave the environment unmodified.
The invoked shell is your login shell, and no directory changes are made.
As a security precaution, if the target user's shell is a non-standard
shell (as defined by
.Xr getusershell 3 )
and the caller's real uid is
non-zero,
.Nm
will fail.
.El
.Pp
The
.Fl l
and
.Fl m
options are mutually exclusive; the last one specified
overrides any previous ones.
.Pp
Only users in group
.Dq wheel
(normally gid 0)
or group
.Dq admin
(normally gid 20) can
.Nm
to
.Dq root .
.Pp
By default (unless the prompt is reset by a startup file) the super-user
prompt is set to
.Dq Sy \&#
to remind one of its awesome power.
.Sh SEE ALSO
.Xr csh 1 ,
.Xr login 1 ,
.Xr sh 1 ,
.Xr skey 1 ,
.Xr kinit 1 ,
.Xr kerberos 1 ,
.Xr passwd 5 ,
.Xr group 5 ,
.Xr environ 7
.Sh ENVIRONMENT
Environment variables used by
.Nm 
:
.Bl -tag -width "HOME"
.It Ev HOME
Default home directory of real user ID unless modified as
specified above.
.It Ev PATH
Default search path of real user ID unless modified as specified above.
.It Ev TERM
Provides terminal type which may be retained for the substituted
user ID.
.It Ev USER
The user ID is always the effective ID (the target user ID) after an
.Nm
unless the user ID is 0 (root).
.El
.Sh HISTORY
A
.Nm
command appeared in
.At v7 .
Commit	Line	Data
44bd5ea7 A	1	.\" Copyright (c) 1988, 1990, 1993, 1994
	2	.\" The Regents of the University of California. All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	11	.\" documentation and/or other materials provided with the distribution.
	12	.\" 3. All advertising materials mentioning features or use of this software
	13	.\" must display the following acknowledgement:
	14	.\" This product includes software developed by the University of
	15	.\" California, Berkeley and its contributors.
	16	.\" 4. Neither the name of the University nor the names of its contributors
	17	.\" may be used to endorse or promote products derived from this software
	18	.\" without specific prior written permission.
	19	.\"
	20	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	.\" SUCH DAMAGE.
	31	.\"
	32	.\" from: @(#)su.1 8.2 (Berkeley) 4/18/94
	33	.\" $NetBSD: su.1,v 1.14 1997/10/19 23:31:52 lukem Exp $
	34	.\"
	35	.Dd April 18, 1994
	36	.Dt SU 1
	37	.Os
	38	.Sh NAME
	39	.Nm su
	40	.Nd substitute user identity
	41	.Sh SYNOPSIS
	42	.Nm
c0fcf4e1 A	43	.Op Fl flm
	44	.Op Ar login
	45	.Op Ar -c shell arguments
44bd5ea7 A	46	.Sh DESCRIPTION
44bd5ea7 A	47	.Nm
c0fcf4e1	48	requests the password for
44bd5ea7	49	.Ar login
c0fcf4e1 A	50	and switches to
c0fcf4e1 A	51	that user and group ID after obtaining proper authentication.
44bd5ea7 A	52	A shell is then executed, and any additional
	53	.Ar "shell arguments"
	54	after the login name
	55	are passed to the shell.
44bd5ea7 A	56	If
	57	.Nm
	58	is executed by root, no password is requested and a shell
c0fcf4e1	59	with the appropriate user ID is executed.
44bd5ea7 A	60	.Pp
	61	The options are as follows:
	62	.Bl -tag -width Ds
c0fcf4e1 A	63	.It Fl c
c0fcf4e1 A	64	Invoke the following command in a subshell as the specified user.
44bd5ea7 A	65	.It Fl f
	66	If the invoked shell is
	67	.Xr csh 1 ,
	68	this option prevents it from reading the
	69	.Dq Pa .cshrc
	70	file.
	71	.It Fl l
	72	Simulate a full login.
	73	The environment is discarded except for
	74	.Ev HOME ,
	75	.Ev SHELL ,
	76	.Ev PATH ,
	77	.Ev TERM ,
	78	and
	79	.Ev USER .
	80	.Ev HOME
	81	and
	82	.Ev SHELL
	83	are modified as above.
	84	.Ev USER
	85	is set to the target login.
	86	.Ev PATH
	87	is set to
	88	.Dq Pa /bin:/usr/bin .
	89	.Ev TERM
	90	is imported from your current environment.
	91	The invoked shell is the target login's, and
	92	.Nm
	93	will change directory to the target login's home directory.
c0fcf4e1	94	This option is identical to just passing "-", as in "su -".
44bd5ea7 A	95	.It Fl m
	96	Leave the environment unmodified.
	97	The invoked shell is your login shell, and no directory changes are made.
	98	As a security precaution, if the target user's shell is a non-standard
	99	shell (as defined by
	100	.Xr getusershell 3 )
	101	and the caller's real uid is
	102	non-zero,
	103	.Nm
	104	will fail.
	105	.El
	106	.Pp
	107	The
	108	.Fl l
	109	and
	110	.Fl m
	111	options are mutually exclusive; the last one specified
	112	overrides any previous ones.
	113	.Pp
	114	Only users in group
	115	.Dq wheel
c0fcf4e1 A	116	(normally gid 0)
	117	or group
	118	.Dq admin
	119	(normally gid 20) can
44bd5ea7 A	120	.Nm
	121	to
	122	.Dq root .
	123	.Pp
	124	By default (unless the prompt is reset by a startup file) the super-user
	125	prompt is set to
	126	.Dq Sy \&#
	127	to remind one of its awesome power.
	128	.Sh SEE ALSO
	129	.Xr csh 1 ,
	130	.Xr login 1 ,
	131	.Xr sh 1 ,
	132	.Xr skey 1 ,
	133	.Xr kinit 1 ,
	134	.Xr kerberos 1 ,
	135	.Xr passwd 5 ,
	136	.Xr group 5 ,
	137	.Xr environ 7
	138	.Sh ENVIRONMENT
	139	Environment variables used by
	140	.Nm
	141	:
	142	.Bl -tag -width "HOME"
	143	.It Ev HOME
	144	Default home directory of real user ID unless modified as
	145	specified above.
	146	.It Ev PATH
	147	Default search path of real user ID unless modified as specified above.
	148	.It Ev TERM
	149	Provides terminal type which may be retained for the substituted
	150	user ID.
	151	.It Ev USER
	152	The user ID is always the effective ID (the target user ID) after an
	153	.Nm
	154	unless the user ID is 0 (root).
	155	.El
	156	.Sh HISTORY
	157	A
	158	.Nm
	159	command appeared in
	160	.At v7 .