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.\"     @(#)setreuid.2	6.4 (Berkeley) 3/10/91
.\"
.Dd March 10, 1991
.Dt SETREUID 2
.Os BSD 4
.Sh NAME
.Nm setreuid
.Nd set real and effective user ID's
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
.Fn setreuid "int ruid" "int euid"
.Sh DESCRIPTION
The real and effective user ID's of the
current process are set according to the arguments.
If
.Fa ruid
or 
.Fa euid
is -1, the current uid is filled in by the system.
Unprivileged users may change the real user
ID to the effective user ID and vice-versa; only the super-user may
make other changes.
.Sh RETURN VALUES
Upon successful completion, a value of 0 is returned.  Otherwise,
a value of -1 is returned and
.Va errno
is set to indicate the error.
.Sh ERRORS
.Bl -tag -width [EPERM]
.It Bq Er 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.
.El
.Sh SEE ALSO
.Xr getuid 2 ,
.Xr setregid 2 ,
.Xr setuid 3
.Sh HISTORY
The
.Nm
function call appeared in
.Bx 4.2 .