-.\" $OpenBSD: unifdef.1,v 1.21 2014/04/30 06:06:09 jmc Exp $
+.\" $OpenBSD: unifdef.1,v 1.22 2014/05/03 14:13:52 jmc Exp $
.\" Copyright (c) 1985, 1991, 1993
.\" The Regents of the University of California. All rights reserved.
.\" Copyright (c) 2002 - 2013 Tony Finch <dot@dotat.at>. All rights reserved.
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
-.Dd $Mdocdate: April 30 2014 $
+.Dd $Mdocdate: May 3 2014 $
.Dt UNIFDEF 1
.Os
.Sh NAME
.Fl U
command line options or in
.Fl f
-definitions files.
+definition files.
A directive is processed
if the macro specifications are sufficient to provide
a definite value for its control expression.
.Ic #define
in a
.Fl f
-definitions file,
+definition file,
its arguments are ignored.
If a macro is explicitly undefined on the command line with the
.Fl U
.Ic #undef
in a
.Fl f
-definitions file,
+definition file,
it may not have any arguments since this leads to a syntax error.
.Pp
The
The
.Nm
utility works nicely with the
-.Fl D Ns Ar sym
+.Fl D
option of
.Xr diff 1 .
.Sh EXIT STATUS