setreuid, setregid - set real and/or effective user or group ID
- include __
int setreuid(uid_t ruid, uid_t
int setregid(gid_t rgid, gid_t
setreuid sets real and effective user IDs of the
current process. Unprivileged users may only set the real
user ID to the real user ID or the effective user ID, and
may only set the effective user ID to the real user ID, the
effective user ID or the saved user ID.
Supplying a value of -1 for either the real or effective
user ID forces the system to leave that ID
If the real user ID is set or the effective user ID is set
to a value not equal to the previous real user ID, the saved
user ID will be set to the new effective user
Completely analogously, setregid sets real and
effective group ID's of the current process, and all of the
above holds with
On success, zero is returned. On error, -1 is returned, and
errno is set appropriately.
The current process is not the super-user and changes other
than (i) swapping the effective user (group) ID with the
real user (group) ID, or (ii) setting one to the value of
the other or (iii) setting the effective user (group) ID to
the value of the saved user (group) ID was
Setting the effective user (group) ID to the saved user ID
is possible since Linux 1.1.37 (1.1.38).
BSD 4.3 (the setreuid and setregid function
calls first appeared in 4.2BSD).
getuid(2), getgid(2), setuid(2),