usr/man/man2/setreuid.2

.TH SETREUID 2 "12 February 1983"
.UC 4
.SH NAME
setreuid \- set real and effective user ID's
.SH SYNOPSIS
.ft B
.nf
setreuid(ruid, euid)
int ruid, euid;
.fi
.ft R
.SH DESCRIPTION
The real and effective user ID's of the
current process are set according to the arguments.
If
.I ruid
or
.I euid
is \-1, the current uid is filled in by the system.
Only the super-user may modify the real uid of
a process.  Users other than the super-user may
change the effective uid of a process only to the
real uid.
.SH "RETURN VALUE
Upon successful completion, a value of 0 is returned.  Otherwise,
a value of \-1 is returned and \fIerrno\fP is set to indicate the error.
.SH "ERRORS
.TP 15
[EPERM]
The current process is not the super-user and a change
other than changing the effective user-id to the real user-id
was specified.
.SH "SEE ALSO"
getuid(2), setregid(2), setuid(3)