1SETREUID(2)                Linux Programmer's Manual               SETREUID(2)
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NAME

6       setreuid, setregid - set real and/or effective user or group ID
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SYNOPSIS

9       #include <sys/types.h>
10       #include <unistd.h>
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12       int setreuid(uid_t ruid, uid_t euid);
13       int setregid(gid_t rgid, gid_t egid);
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15   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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17       setreuid(), setregid(): _BSD_SOURCE || _XOPEN_SOURCE >= 500
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DESCRIPTION

20       setreuid() sets real and effective user IDs of the calling process.
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22       Supplying a value of -1 for either the real or effective user ID forces
23       the system to leave that ID unchanged.
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25       Unprivileged processes may only set the effective user ID to  the  real
26       user ID, the effective user ID or the saved set-user-ID.
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28       POSIX:  It  is  unspecified  whether unprivileged processes may set the
29       real user ID to the real user ID, the effective user ID  or  the  saved
30       set-user-ID.
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32       Linux:  Unprivileged  users  may  only set the real user ID to the real
33       user ID or the effective user ID.
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35       Linux: If the real user ID is set or the effective user ID is set to  a
36       value  not  equal  to  the previous real user ID, the saved set-user-ID
37       will be set to the new effective user ID.
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39       Completely analogously, setregid() sets real and effective  group  ID's
40       of the calling process, and all of the above holds with "group" instead
41       of "user".
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RETURN VALUE

44       On success, zero is returned.  On error, -1 is returned, and  errno  is
45       set appropriately.
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ERRORS

48       EPERM  The  calling process is not privileged (Linux: does not have the
49              CAP_SETUID capability in the case of setreuid(), or the CAP_SET‐
50              GID  capability  in  the  case of setregid()) and a change other
51              than (i) swapping the effective user (group) ID  with  the  real
52              user  (group)  ID, or (ii) setting one to the value of the other
53              or (iii) setting the effective user (group) ID to the  value  of
54              the saved set-user-ID (saved set-group-ID) was specified.
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CONFORMING TO

57       POSIX.1-2001,  4.3BSD  (the  setreuid()  and  setregid() function calls
58       first appeared in 4.2BSD).
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NOTES

61       Setting the effective user (group) ID to the saved  set-user-ID  (saved
62       set-group-ID) is possible since Linux 1.1.37 (1.1.38).
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SEE ALSO

65       getgid(2),  getuid(2),  seteuid(2), setgid(2), setresuid(2), setuid(2),
66       capabilities(7)
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COLOPHON

69       This page is part of release 3.22 of the Linux  man-pages  project.   A
70       description  of  the project, and information about reporting bugs, can
71       be found at http://www.kernel.org/doc/man-pages/.
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75Linux                             2007-07-26                       SETREUID(2)
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