Annotation of src/usr.bin/su/su.1, Revision 1.2
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32: .\" from: @(#)su.1 6.12 (Berkeley) 7/29/91
1.2 ! deraadt 33: .\" $Id: su.1,v 1.1.1.1 1995/10/18 08:46:09 deraadt Exp $
1.1 deraadt 34: .\"
35: .Dd July 29, 1991
36: .Dt SU 1
37: .Os
38: .Sh NAME
39: .Nm su
40: .Nd substitute user identity
41: .Sh SYNOPSIS
42: .Nm su
43: .Op Fl Kflm
44: .Op Ar login Op Ar "shell arguments"
45: .Sh DESCRIPTION
46: .Nm Su
47: requests the Kerberos password for
48: .Ar login
49: (or for
50: .Dq Ar login Ns .root ,
51: if no login is provided), and switches to
52: that user and group ID after obtaining a Kerberos ticket granting ticket.
53: A shell is then executed, and any additional
54: .Ar "shell arguments"
55: after the login name
56: are passed to the shell.
57: .Nm Su
58: will resort to the local password file to find the password for
59: .Ar login
60: if there is a Kerberos error.
61: If
62: .Nm su
63: is executed by root, no password is requested and a shell
64: with the appropriate user ID is executed; no additional Kerberos tickets
65: are obtained.
66: .Pp
67: Alternately, if the user enters the password "s/key", they will be
68: authenticated using the S/Key one-time password system as described in
69: .Xr skey 1 .
70: S/Key is a Trademark of Bellcore.
71: .Pp
72: By default, the environment is unmodified with the exception of
73: .Ev USER ,
74: .Ev HOME ,
75: and
76: .Ev SHELL .
77: .Ev HOME
78: and
79: .Ev SHELL
80: are set to the target login's default values.
81: .Ev USER
82: is set to the target login, unless the target login has a user ID of 0,
83: in which case it is unmodified.
84: The invoked shell is the target login's.
85: This is the traditional behavior of
86: .Nm su .
87: .Pp
88: The options are as follows:
89: .Bl -tag -width Ds
90: .It Fl K
91: Do not attempt to use Kerberos to authenticate the user.
92: .It Fl f
93: If the invoked shell is
94: .Xr csh 1 ,
95: this option prevents it from reading the
96: .Dq Pa .cshrc
97: file.
98: .It Fl l
99: Simulate a full login.
100: The environment is discarded except for
101: .Ev HOME ,
102: .Ev SHELL ,
103: .Ev PATH ,
104: .Ev TERM ,
105: and
106: .Ev USER .
107: .Ev HOME
108: and
109: .Ev SHELL
110: are modified as above.
111: .Ev USER
112: is set to the target login.
113: .Ev PATH
114: is set to
115: .Dq Pa /bin:/usr/bin .
116: .Ev TERM
117: is imported from your current environment.
118: The invoked shell is the target login's, and
119: .Nm su
120: will change directory to the target login's home directory.
121: .It Fl m
122: Leave the environment unmodified.
123: The invoked shell is your login shell, and no directory changes are made.
124: As a security precaution, if the target user's shell is a non-standard
125: shell (as defined by
126: .Xr getusershell 3 )
127: and the caller's real uid is
128: non-zero,
129: .Nm su
130: will fail.
131: .El
132: .Pp
133: The
134: .Fl l
135: and
136: .Fl m
137: options are mutually exclusive; the last one specified
138: overrides any previous ones.
139: .Pp
1.2 ! deraadt 140: If group 0 (normally
1.1 deraadt 141: .Dq wheel )
1.2 ! deraadt 142: has users listed then only those users can
! 143: .Nm su
! 144: to
! 145: .Dq root .
! 146: Otherwise, anyone can
1.1 deraadt 147: .Nm su
148: to
149: .Dq root .
150: .Pp
151: By default (unless the prompt is reset by a startup file) the super-user
152: prompt is set to
153: .Dq Sy \&#
154: to remind one of its awesome power.
155: .Sh SEE ALSO
156: .Xr csh 1 ,
157: .Xr login 1 ,
158: .Xr sh 1 ,
159: .Xr skey 1 ,
160: .Xr kinit 1 ,
161: .Xr kerberos 1 ,
162: .Xr passwd 5 ,
163: .Xr group 5 ,
164: .Xr environ 7
165: .Sh ENVIRONMENT
166: Environment variables used by
167: .Nm su :
168: .Bl -tag -width HOME
169: .It Ev HOME
170: Default home directory of real user ID unless modified as
171: specified above.
172: .It Ev PATH
173: Default search path of real user ID unless modified as specified above.
174: .It Ev TERM
175: Provides terminal type which may be retained for the substituted
176: user ID.
177: .It Ev USER
178: The user ID is always the effective ID (the target user ID) after an
179: .Nm su
180: unless the user ID is 0 (root).
181: .El
182: .Sh HISTORY
183: A
184: .Nm
185: command appeared in
186: .At v7 .
187: The version described
188: here is an adaptation of the
189: .Tn MIT
190: Athena Kerberos command.
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