getresuid(2) System Calls Manual getresuid(2) getresuid, getresgid - , C (libc, -lc) #define _GNU_SOURCE /* . feature_test_macros(7) */ #include int getresuid(uid_t *ruid, uid_t *euid, uid_t *suid); int getresgid(gid_t *rgid, gid_t *egid, gid_t *sgid); getresuid() (real), (effective) (saved) set-user-ID ruid, euid suid, . getresgid() . 0. -1, errno . EFAULT . POSIX.1-2024 XSI. Linux 2.1.44, glibc 2.3.2, POSIX.1-2024 XSI. getresuid() getresgid() Linux 16- . Linux 2.4 getresuid32() getresgid32(), 32- . glibc getresuid() getresgid() . getuid(2), setresuid(2), setreuid(2), setuid(2), credentials(7) () Azamat Hackimov , Dmitry Bolkhovskikh , Vladislav , Yuri Kozlov ; GNU (GNU General Public License - GPL, 3 ) , - . - , , () () () . Linux man-pages 6.18 8 2026 . getresuid(2)