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32 .\" @(#)su.1 8.2 (Berkeley) 4/18/94
40 .Nd substitute user identity
46 .Op Ar login Op Ar args
50 utility requests appropriate user credentials via PAM
51 and switches to that user ID
52 (the default user is the superuser).
53 A shell is then executed.
55 PAM is used to set the policy
58 In particular, by default only users in the
60 group can switch to UID 0
62 This group requirement may be changed by modifying the
68 for details on how to modify this setting.
70 By default, the environment is unmodified with the exception of
78 are set to the target login's default values.
80 is set to the target login, unless the target login has a user ID of 0,
81 in which case it is unmodified.
82 The invoked shell is the one belonging to the target login.
83 This is the traditional behavior of
85 Resource limits and session priority applicable to the original user's
88 are also normally retained unless the target login has a user ID of 0.
90 The options are as follows:
93 If the invoked shell is
95 this option prevents it from reading the
99 Simulate a full login.
100 The environment is discarded except for
110 are modified as above.
112 is set to the target login.
115 .Dq Pa /bin:/usr/bin .
117 is imported from your current environment.
118 Environment variables may be set or overridden from the login class
119 capabilities database according to the class of the target login.
120 The invoked shell is the target login's, and
122 will change directory to the target login's home directory.
123 Resource limits and session priority are modified to that for the
124 target account's login class.
126 (no letter) The same as
129 Leave the environment unmodified.
130 The invoked shell is your login shell, and no directory changes are made.
131 As a security precaution, if the target user's shell is a non-standard
134 and the caller's real uid is
139 Set the MAC label to the user's default label as part of the user
141 Setting the MAC label may fail if the MAC label of the invoking process
142 is not sufficient to transition to the user's default MAC label.
143 If the label cannot be set,
147 Use the settings of the specified login class.
148 Only allowed for the super-user.
157 options are mutually exclusive; the last one specified
158 overrides any previous ones.
162 are provided on the command line, they are passed to the login shell of
164 Note that all command line arguments before the target login name are
167 itself, everything after the target login name gets passed to the login
170 By default (unless the prompt is reset by a startup file) the super-user
173 to remind one of its awesome power.
175 Environment variables used by
179 Default home directory of real user ID unless modified as
182 Default search path of real user ID unless modified as specified above.
184 Provides terminal type which may be retained for the substituted
187 The user ID is always the effective ID (the target user ID) after an
189 unless the user ID is 0 (root).
192 .Bl -tag -width ".Pa /etc/pam.d/su" -compact
194 PAM configuration for
198 .Bl -tag -width 5n -compact
199 .It Li "su -m man -c catman"
200 Starts a shell as user
204 You will be asked for man's password unless your real UID is 0.
207 option is required since user
209 does not have a valid shell by default.
212 is passed to the shell of the user
214 and is not interpreted as an argument to
216 .It Li "su -m man -c 'catman /usr/share/man /usr/local/man'"
217 Same as above, but the target command consists of more than a
218 single word and hence is quoted for use with the
220 option being passed to the shell.
221 (Most shells expect the argument to
223 to be a single word).
224 .It Li "su -m -c staff man -c 'catman /usr/share/man /usr/local/man'"
225 Same as above, but the target command is run with the resource limits of
228 Note: in this example, the first
232 while the second is an argument to the shell being invoked.
234 Simulate a login for user foo.
238 Simulate a login for root.