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28 .\" @(#)su.1 8.2 (Berkeley) 4/18/94
36 .Nd substitute user identity
42 .Op Ar login Op Ar args
46 utility requests appropriate user credentials via PAM
47 and switches to that user ID
48 (the default user is the superuser).
49 A shell is then executed.
51 PAM is used to set the policy
54 In particular, by default only users in the
56 group can switch to UID 0
58 This group requirement may be changed by modifying the
64 for details on how to modify this setting.
66 By default, the environment is unmodified with the exception of
74 are set to the target login's default values.
76 is set to the target login, unless the target login has a user ID of 0,
77 in which case it is unmodified.
78 The invoked shell is the one belonging to the target login.
79 This is the traditional behavior of
81 Resource limits and session priority applicable to the original user's
84 are also normally retained unless the target login has a user ID of 0.
86 The options are as follows:
89 Use the settings of the specified login class.
90 The login class must be defined in
92 Only allowed for the super-user.
94 If the invoked shell is
96 this option prevents it from reading the
100 Simulate a full login.
101 The environment is discarded except for
111 are modified as above.
113 is set to the target login.
116 .Dq Pa /bin:/usr/bin .
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
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.
127 (no letter) The same as
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
135 and the caller's real uid is
140 Set the MAC label to the user's default label as part of the user
142 Setting the MAC label may fail if the MAC label of the invoking process
143 is not sufficient to transition to the user's default MAC label.
144 If the label cannot be set,
155 options are mutually exclusive; the last one specified
156 overrides any previous ones.
160 are provided on the command line, they are passed to the login shell of
162 Note that all command line arguments before the target login name are
165 itself, everything after the target login name gets passed to the login
168 By default (unless the prompt is reset by a startup file) the super-user
171 to remind one of its awesome power.
173 Environment variables used by
177 Default home directory of real user ID unless modified as
180 Default search path of real user ID unless modified as specified above.
182 Provides terminal type which may be retained for the substituted
185 The user ID is always the effective ID (the target user ID) after an
187 unless the user ID is 0 (root).
190 .Bl -tag -width ".Pa /etc/pam.d/su" -compact
192 PAM configuration for
196 .Bl -tag -width 5n -compact
197 .It Li "su -m man -c catman"
198 Starts a shell as user
202 You will be asked for man's password unless your real UID is 0.
205 option is required since user
207 does not have a valid shell by default.
210 is passed to the shell of the user
212 and is not interpreted as an argument to
214 .It Li "su -m man -c 'catman /usr/share/man /usr/local/man'"
215 Same as above, but the target command consists of more than a
216 single word and hence is quoted for use with the
218 option being passed to the shell.
219 (Most shells expect the argument to
221 to be a single word).
222 .It Li "su -m -c staff man -c 'catman /usr/share/man /usr/local/man'"
223 Same as above, but the target command is run with the resource limits of
226 Note: in this example, the first
230 while the second is an argument to the shell being invoked.
232 Simulate a login for user foo.
236 Simulate a login for root.