setresuid, setresgid - set real, effective and saved user
or group ID
int setresuid(uid_t ruid, uid_t euid, uid_t suid);
int setresgid(gid_t rgid, gid_t egid, gid_t sgid);
setresuid (introduced in Linux 2.1.44) sets the real user
ID, the effective user ID, and the saved set-user-ID of
the current process.
Unprivileged user processes (i.e., processes with each of
real, effective and saved user ID nonzero) may change the
real, effective and saved user ID, each to one of: the
current uid, the current effective uid or the current
The super-user may set real, effective and saved user ID
to arbitrary values.
If one of the parameters equals -1, the corresponding
value is not changed.
Completely analogously, setresgid sets the real, effective
and saved group ID's of the current process, with the same
restrictions for processes with each of real, effective
and saved user ID nonzero.
On success, zero is returned. On error, -1 is returned,
and errno is set appropriately.
EPERM The current process was not privileged and tried to
change the IDs is a not allowed way.
This call is Linux-specific.
getuid(2), setuid(2), getreuid(2), setreuid(2), getre