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SETRESUID(2) Linux Programmer's Manual SETRESUID(2)
setresuid, setresgid - set real, effective and saved user or group ID
#define _GNU_SOURCE /* See feature_test_macros(7) */
#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);
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
unprivileged processes.
On success, zero is returned. On error, -1 is returned, and errno is set
appropriately.
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.
These calls are available under Linux since Linux 2.1.44.
These calls are nonstandard; they also appear on HP-UX and some of the BSDs.
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.
The original Linux setresuid() and setresgid() system calls supported only
16-bit user and group IDs. Subsequently, Linux 2.4 added setresuid32() and
setresgid32(), supporting 32-bit IDs. The glibc setresuid() and setresgid()
wrapper functions transparently deal with the variations across kernel
versions.
getresuid(2), getuid(2), setfsgid(2), setfsuid(2), setreuid(2), setuid(2),
capabilities(7), credentials(7)
This page is part of release 3.32 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 2010-11-22 SETRESUID(2)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface