setreuid - set real and effective user IDs
int setreuid(uid_t ruid, uid_t euid);
The setreuid() function sets the real and effective user IDs of the
current process to the values specified by the ruid and euid
arguments. If ruid or euid is -1, the corresponding effective or real
user ID of the current process is left unchanged.
A process with appropriate privileges can set either ID to any value.
An unprivileged process can only set the effective user ID if the euid
argument is equal to either the real, effective, or saved user ID of
It is unspecified whether a process without appropriate privileges is
permitted to change the real user ID to match the current real,
effective or saved user ID of the process.
Upon successful completion, 0 is returned. Otherwise, -1 is returned
and errno is set to indicate the error.
The setreuid() function will fail if:
[EINVAL] The value of the ruid or euid argument
is invalid or out-of-range.
[EPERM] The current process does not have
appropriate privileges, and either an
attempt was made to change the effective
user ID to a value other than the real
user ID or the saved set-user-ID or an
attempt was made to change the real user
ID to a value not permitted by the
getuid(2), setuid(2), <unistd.h>.
First released in Issue 4, Version 2.
Hewlett-Packard Company - 1 - HP-UX Release 11i: November 2000