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1 .\" $NetBSD: setreuid.2,v 1.23 2008/05/02 18:11:05 martin Exp $
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58 .\" from: @(#)setreuid.2 6.4 (Berkeley) 3/10/91
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60 .Dd January 5, 2001
61 .Dt SETREUID 2
62 .Os
63 .Sh NAME
64 .Nm setreuid
65 .Nd set real and effective user ID's
66 .Sh LIBRARY
67 .Lb libc
68 .Sh SYNOPSIS
69 .In unistd.h
70 .Ft int
71 .Fn setreuid "uid_t ruid" "uid_t euid"
72 .Sh DESCRIPTION
73 .Bf -symbolic
74 This interface is made obsolete by the saved ID functionality in
75 .Xr setuid 2
76 and
77 .Xr seteuid 2 .
78 .Ef
79 .Pp
80 The real and effective user ID's of the
81 current process are set according to the arguments.
82 If the real user ID is changed, the saved user ID is changed to the new
83 value of the effective user ID.
84 .Pp
85 If
86 .Fa ruid
87 or
88 .Fa euid
89 is \-1, the current uid is filled in by the system.
90 Unprivileged users may change the real user
91 ID to the effective user ID, and may change the effective user ID to the
92 real user ID or the saved user ID; only the super-user may
93 make other changes.
94 .Pp
95 The
96 .Fn setreuid
97 function has been used to swap the real and effective user
98 IDs in set-user-ID programs to temporarily relinquish the set-user-ID
99 value.
100 This purpose is now better served by the use of the
101 .Fn seteuid
102 function (see
103 .Xr setuid 2 ) .
104 .Pp
105 When setting the real and effective user IDs to the same value, this
106 function is equivalent to the
107 .Fn setuid
108 function.
109 When setting only the effective user ID, this function is equivalent to
110 the
111 .Fn seteuid
112 function.
113 .Sh RETURN VALUES
114 Upon successful completion, a value of 0 is returned.
115 Otherwise, a value of \-1 is returned and
116 .Va errno
117 is set to indicate the error.
118 .Sh ERRORS
119 .Bl -tag -width Er
120 .It Bq Er EPERM
121 The current process is not the super-user and a change
122 other than changing the effective user-id to the real user-id
123 was specified.
124 .El
125 .Sh SEE ALSO
126 .Xr getuid 2 ,
127 .Xr seteuid 2 ,
128 .Xr setgid 2 ,
129 .Xr setuid 2
130 .Sh HISTORY
131 The
132 .Fn setreuid
133 function call appeared in
134 .Bx 4.2 .
135 An incompatible version was implemented in
136 .Bx 4.4 .
137 It was reimplemented in
138 .Nx 1.2
139 in a way compatible with
140 .Bx 4.3 ,
141 SunOS and Linux, but should not be used in new code.