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NAME

       seteuid, setegid - set effective user or group ID

SYNOPSIS

       #include <sys/types.h>
       #include <unistd.h>

       int seteuid(uid_t euid);
       int setegid(gid_t egid);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       seteuid(), setegid(): _BSD_SOURCE || _POSIX_C_SOURCE >= 200112L ||
       _XOPEN_SOURCE >= 600

DESCRIPTION

       seteuid()  sets  the  effective  user  ID  of  the   calling   process.
       Unprivileged  user  processes may only set the effective user ID to the
       real user ID, the effective user ID or the saved set-user-ID.

       Precisely the same holds for setegid() with "group" instead of  "user".

RETURN VALUE

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

ERRORS

       EPERM  The calling process is not privileged (Linux: does not have  the
              CAP_SETUID   capability   in  the  case  of  seteuid(),  or  the
              CAP_SETGID  capability  in  the  case  of  setegid())  and  euid
              (respectively,  egid)  is  not  the  real  user  (group) ID, the
              effective user (group) ID, or the saved set-user-ID (saved  set-
              group-ID).

CONFORMING TO

       4.3BSD, POSIX.1-2001.

NOTES

       Setting  the  effective user (group) ID to the saved set-user-ID (saved
       set-group-ID) is possible since Linux 1.1.37 (1.1.38).  On an arbitrary
       system one should check _POSIX_SAVED_IDS.

       Under  libc4,  libc5  and  glibc  2.0  seteuid(euid)  is  equivalent to
       setreuid(-1, euid) and hence may change the saved  set-user-ID.   Under
       glibc  2.1  and  later  it is equivalent to setresuid(-1, euid, -1) and
       hence does not change the saved set-user-ID.  Similar remarks hold  for
       setegid().

       According to POSIX.1, seteuid() (setegid()) need not permit euid (egid)
       to be the same value as the current effective user (group) ID, and some
       implementations do not permit this.

SEE ALSO

       geteuid(2),   setresuid(2),  setreuid(2),  setuid(2),  capabilities(7),
       credentials(7)

COLOPHON

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