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



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
       This page is part of release 3.25 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                                                      2009-10-17                                                 SETEUID(2)