int setresuid(uid_t ruid, uid_t euid, uid_t suid); int setresgid(gid_t rgid, gid_t egid, gid_t sgid);
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.
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.
On success, zero is returned.
On error, -1 is returned, and
is set appropriately.
does not match the current UID and this call would
bring that user ID over its
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 non-standard;
they also appear on HP-UX and some of the BSDs.
Under HP-UX and FreeBSD the prototype is found in
Under Linux the prototype is provided by glibc since version 2.3.2.