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

6       seteuid, setegid - set 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 seteuid(uid_t euid);
13       int setegid(gid_t egid);
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15   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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17       seteuid(), setegid(): _BSD_SOURCE || _POSIX_C_SOURCE >= 200112L ||
18       _XOPEN_SOURCE >= 600
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DESCRIPTION

21       seteuid() sets the effective user ID of the calling process.   Unprivi‐
22       leged  user  processes  may  only set the effective user ID to the real
23       user ID, the effective user ID or the saved set-user-ID.
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25       Precisely the same holds for setegid() with "group" instead of "user".
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RETURN VALUE

28       On success, zero is returned.  On error, -1 is returned, and  errno  is
29       set appropriately.
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ERRORS

32       EPERM  The  calling process is not privileged (Linux: does not have the
33              CAP_SETUID capability in the case of seteuid(), or the  CAP_SET‐
34              GID capability in the case of setegid()) and euid (respectively,
35              egid) is not the  real  user  (group)  ID,  the  effective  user
36              (group) ID, or the saved set-user-ID (saved set-group-ID).
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CONFORMING TO

39       4.3BSD, POSIX.1-2001.
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NOTES

42       Setting  the  effective user (group) ID to the saved set-user-ID (saved
43       set-group-ID) is possible since Linux 1.1.37 (1.1.38).  On an arbitrary
44       system one should check _POSIX_SAVED_IDS.
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46       Under  libc4,  libc5  and  glibc  2.0  seteuid(euid)  is  equivalent to
47       setreuid(-1, euid) and hence may change the saved  set-user-ID.   Under
48       glibc  2.1  and  later  it is equivalent to setresuid(-1, euid, -1) and
49       hence does not change the saved set-user-ID.  Similar remarks hold  for
50       setegid().
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52       According to POSIX.1, seteuid() (setegid()) need not permit euid (egid)
53       to be the same value as the current effective user (group) ID, and some
54       implementations do not permit this.
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SEE ALSO

57       geteuid(2), setresuid(2), setreuid(2), setuid(2), capabilities(7), cre‐
58       dentials(7)
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COLOPHON

61       This page is part of release 3.25 of the Linux  man-pages  project.   A
62       description  of  the project, and information about reporting bugs, can
63       be found at http://www.kernel.org/doc/man-pages/.
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67Linux                             2009-10-17                        SETEUID(2)
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