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.  Analogous remarks hold for setegid(), with the difference that
       the change in implementation from setregid(-1, egid) to setresgid(-1, egid, -1) occurred in glibc 2.2  or
       2.3 (dependeing on the hardware architecture).

       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

       This page is part of release 3.54 of the Linux man-pages project.  A  description  of  the  project,  and
       information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.

Linux                                              2012-07-02                                         SETEUID(2)