| blob | 6f905f5bf8d50b4ce92845c6c32fe4d16953d516 |
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 .\" @(#)su.1 8.2 (Berkeley) 4/18/94
33 .\" $FreeBSD: src/usr.bin/su/su.1,v 1.17.2.6 2002/06/21 15:29:18 charnier Exp $
34 .\" $DragonFly: src/usr.bin/su/su.1,v 1.6 2007/03/25 11:35:11 swildner Exp $
35 .\"
36 .Dd April 18, 1994
37 .Dt SU 1
38 .Os
39 .Sh NAME
40 .Nm su
41 .Nd substitute user identity
42 .Sh SYNOPSIS
43 .Nm
44 .Op Fl
45 .Op Fl Kflm
46 .Op Fl c Ar class
47 .Op Ar login Op Ar args
48 .Sh DESCRIPTION
49 The
50 .Nm
51 utility requests the Kerberos password for
52 .Ar login
53 (or for
54 .Dq Ar login Ns .root ,
55 if no login is provided), and switches to
56 that user and group ID after obtaining a Kerberos ticket granting ticket.
57 A shell is then executed.
58 The
59 .Nm
60 utility will resort to the local password file to find the password for
61 .Ar login
62 if there is a Kerberos error.
63 If
64 .Nm
65 is executed by root, no password is requested and a shell
66 with the appropriate user ID is executed; no additional Kerberos tickets
67 are obtained.
68 .Pp
69 By default, the environment is unmodified with the exception of
70 .Ev USER ,
71 .Ev HOME ,
72 and
73 .Ev SHELL .
74 .Ev HOME
75 and
76 .Ev SHELL
77 are set to the target login's default values.
78 .Ev USER
79 is set to the target login, unless the target login has a user ID of 0,
80 in which case it is unmodified.
81 The invoked shell is the target login's.
82 This is the traditional behavior of
83 .Nm .
84 Resource limits and session priority applicable to the original user's
85 login class (See
86 .Xr login.conf 5 )
87 are also normally retained unless the target login has a user ID of 0.
88 .Pp
89 The options are as follows:
90 .Bl -tag -width Ds
91 .It Fl K
92 Do not attempt to use Kerberos to authenticate the user.
93 .It Fl f
94 If the invoked shell is
95 .Xr csh 1 ,
96 this option prevents it from reading the
97 .Dq Pa .cshrc
98 file.
99 .It Fl l
100 Simulate a full login.
101 The environment is discarded except for
102 .Ev HOME ,
103 .Ev SHELL ,
104 .Ev PATH ,
105 .Ev TERM ,
106 and
107 .Ev USER .
108 .Ev HOME
109 and
110 .Ev SHELL
111 are modified as above.
112 .Ev USER
113 is set to the target login.
114 .Ev PATH
115 is set to
116 .Dq Pa /bin:/usr/bin .
117 .Ev TERM
118 is imported from your current environment.
119 Environment variables may be set or overridden from the login class
120 capabilities database according to the class of the target login.
121 The invoked shell is the target login's, and
122 .Nm
123 will change directory to the target login's home directory.
124 Resource limits and session priority are modified to that for the
125 target account's login class.
126 .It Fl
127 (no letter) The same as
128 .Fl l .
129 .It Fl m
130 Leave the environment unmodified.
131 The invoked shell is your login shell, and no directory changes are made.
132 As a security precaution, if the target user's shell is a non-standard
133 shell (as defined by
134 .Xr getusershell 3 )
135 and the caller's real uid is
136 non-zero,
137 .Nm
138 will fail.
139 .It Fl c Ar class
140 Use the settings of the specified login class.
141 Only allowed for the super-user.
142 .El
143 .Pp
144 The
145 .Fl l
146 (or
147 .Fl )
148 and
149 .Fl m
150 options are mutually exclusive; the last one specified
151 overrides any previous ones.
152 .Pp
153 If the optional
154 .Ar args
155 are provided on the command line, they are passed to the login shell of
156 the target login.
157 .Pp
158 Only users who are a member of group 0 (normally
159 .Dq wheel )
160 can
161 .Nm
162 to
163 .Dq root .
164 \ If group 0 is missing or empty, any user can
165 .Nm
166 to
167 .Dq root .
168 .Pp
169 By default (unless the prompt is reset by a startup file) the super-user
170 prompt is set to
171 .Dq Sy \&#
172 to remind one of its awesome power.
173 .Sh ENVIRONMENT
174 Environment variables used by
175 .Nm :
176 .Bl -tag -width HOME
177 .It Ev HOME
178 Default home directory of real user ID unless modified as
179 specified above.
180 .It Ev PATH
181 Default search path of real user ID unless modified as specified above.
182 .It Ev TERM
183 Provides terminal type which may be retained for the substituted
184 user ID.
185 .It Ev USER
186 The user ID is always the effective ID (the target user ID) after an
187 .Nm
188 unless the user ID is 0 (root).
189 .El
190 .Sh FILES
191 .Bl -tag -width /etc/auth.conf -compact
192 .It Pa /etc/auth.conf
193 configure authentication services
194 .El
195 .Sh EXAMPLES
196 .Bl -tag -width 5n -compact
197 .It Li "su man -c catman"
198 Runs the command
199 .Li catman
200 as user
201 .Li man ,
202 assuming man's shell supports the
203 .Fl c
204 option.
205 You will be asked for man's password unless your real UID is 0.
206 .It Li "su -m man -c catman"
207 Same as above, but use the shell and environment of the current
208 user instead of those of man.
209 This allows commands to be executed as user man even when man's shell is
210 .Xr nologin 8 .
211 .It Li "su -mf man -c catman"
212 Same as above, but do not re-evaluate the current user's
213 .Pa .cshrc
214 either.
215 .It Li "su -mf man -c 'catman /usr/share/man /usr/local/man /usr/pkg/xorg/man'"
216 Same as above, but the target command consists of more than a
217 single word and hence is quoted for use with the
218 .Fl c
219 option being passed to the shell. (Most shells expect the argument to
220 .Fl c
221 to be a single word).
222 .It Li "su -mf -c staff man -c 'catman /usr/share/man /usr/local/man /usr/pkg/xorg/man'"
223 Same as above, but the target command is run with the resource limits of
224 the login class
225 .Dq staff .
226 Note: in this example, the first
227 .Fl c
228 option applies to
229 .Nm
230 while the second is an argument to the shell being invoked.
231 .It Li "su -l foo"
232 Simulate a login for user foo.
233 .It Li "su - foo"
234 Same as above.
235 .It Li "su - "
236 Simulate a login for root.
237 .El
238 .Sh SEE ALSO
239 .Xr csh 1 ,
240 .Xr kinit 1 ,
241 .Xr login 1 ,
242 .Xr sh 1 ,
243 .Xr group 5 ,
244 .Xr login.conf 5 ,
245 .Xr passwd 5 ,
246 .Xr environ 7 ,
247 .Xr kerberos 8 ,
248 .Xr nologin 8
249 .Sh HISTORY
250 A
251 .Nm
252 command appeared in
253 .At v1 .