getresuid(2) - BetterMan

getresuid(2)

get real, effective, and saved user/group IDs

distropkg manpages-dev@6.9.1-1dataset 2026-04-01T06:19:02Z+debian+ec4110e+mandoc:1.14.6-4

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
);

—

Options · 1

EFAULT

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

NAME

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

SYNOPSIS

bash

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

bash

int getresuid(uid_t *\nruid\n, uid_t *\neuid\n, uid_t *\nsuid\n);\n
\nint getresgid(gid_t *\nrgid\n, gid_t *\negid\n, gid_t *\nsgid\n);

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 to indicate the error.

ERRORS

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

STANDARDS

None. These calls also appear on HP-UX and some of the BSDs.

HISTORY

Linux 2.1.44, glibc 2.3.2.

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 kernel versions.