GETRESUID(2)              (2017-09-15)               GETRESUID(2)

     NAME
          getresuid, getresgid - get real, effective and saved
          user/group IDs

     SYNOPSIS
          #define _GNU_SOURCE         /* See feature_test_macros(7) */
          #include <unistd.h>

          int getresuid(uid_t *ruid, uid_t *euid, uid_t *suid
          int getresgid(gid_t *rgid, gid_t *egid, gid_t *sgid

     DESCRIPTION
          getresuid() returns the real UID, the effective UID, and the
          saved set-user-ID of the calling process, in the arguments
          ruid, euid, and suid, respectively.  getresgid() performs
          the analogous task for the process's group IDs.

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

     ERRORS
          EFAULT
               One of the arguments specified an address outside the
               calling program's address space.

     VERSIONS
          These system calls appeared on Linux starting with kernel
          2.1.44.

          The prototypes are given by glibc since version 2.3.2, pro-
          vided _GNU_SOURCE is defined.

     CONFORMING TO
          These calls are nonstandard; they also appear on HP-UX and
          some of the BSDs.

     NOTES
          The original Linux getresuid() and getresgid() system calls
          supported only 16-bit user and group IDs.  Subsequently,
          Linux 2.4 added getresuid32() and getresgid32(), supporting
          32-bit IDs.  The glibc getresuid() and getresgid() wrapper
          functions transparently deal with the variations across ker-
          nel versions.

     SEE ALSO
          getuid(2), setresuid(2), setreuid(2), setuid(2),
          credentials(7)

     COLOPHON

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     GETRESUID(2)              (2017-09-15)               GETRESUID(2)

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          found at https://www.kernel.org/doc/man-pages/.

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