SETRESUID

Section: Linux Programmer's Manual (2)
Updated: 2007-07-26
Index Return to Main Contents

NAME

setresuid, setresgid - set real, effective and saved user or group ID

SYNOPSIS

#define _GNU_SOURCE
#include <unistd.h>

int setresuid(uid_t ruid, uid_t euid, uid_t suid);
int setresgid(gid_t rgid, gid_t egid, gid_t sgid);

DESCRIPTION

setresuid() sets the real user ID, the effective user ID, and the saved set-user-ID of the calling process.

Unprivileged user processes may change the real UID, effective UID, and saved set-user-ID, each to one of: the current real UID, the current effective UID or the current saved set-user-ID.

Privileged processes (on Linux, those having the CAP_SETUID capability) may set the real UID, effective UID, and saved set-user-ID to arbitrary values.

If one of the arguments equals -1, the corresponding value is not changed.

Regardless of what changes are made to the real UID, effective UID, and saved set-user-ID, the file system UID is always set to the same value as the (possibly new) effective UID.

Completely analogously, setresgid() sets the real GID, effective GID, and saved set-group-ID of the calling process (and always modifies the file system GID to be the same as the effective GID), with the same restrictions for non-privileged processes.

RETURN VALUE

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

ERRORS

EAGAIN: uid does not match the current UID and this call would bring that user ID over its RLIMIT_NPROC resource limit.
EPERM: The calling process is not privileged (did not have the CAP_SETUID capability) and tried to change the IDs to values that are not permitted.

VERSIONS

These calls are available under Linux since Linux 2.1.44.

CONFORMING TO

These calls are non-standard; they also appear on HP-UX and some of the BSDs.

NOTES

Under HP-UX and FreeBSD the prototype is found in <unistd.h>. Under Linux the prototype is provided by glibc since version 2.3.2.

COLOPHON

This page is part of release 3.05 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/.