+.\" Copyright (c) 1985, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" Dave Yost.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\" notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\" notice, this list of conditions and the following disclaimer in the
+.\" documentation and/or other materials provided with the distribution.
+.\" 3. All advertising materials mentioning features or use of this software
+.\" must display the following acknowledgement:
+.\" This product includes software developed by the University of
+.\" California, Berkeley and its contributors.
+.\" 4. Neither the name of the University nor the names of its contributors
+.\" may be used to endorse or promote products derived from this software
+.\" without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" @(#)unifdef.1 6.5 (Berkeley) 4/23/91
+.\"
+.Dd April 23, 1991
+.Dt UNIFDEF 1
+.Os BSD 4.3
+.Sh NAME
+.Nm unifdef
+.Nd remove ifdef'ed lines
+.Sh SYNOPSIS
+.Nm unifdef
+.Oo
+.Fl t l c
+.Fl D Ns Ar sym
+.Fl U Ns Ar sym
+.Fl iD Ns Ar sym
+.Fl iD Ns Ar sym
+.Oc
+.Ar ...
+.Op Ar file
+.Sh DESCRIPTION
+.Nm Unifdef
+is useful for removing ifdef'ed lines
+from a file while otherwise leaving the file alone.
+.Nm Unifdef
+acts on
+#ifdef, #ifndef, #else, and #endif lines,
+and it knows only enough about C
+to know when one of these is inactive
+because it is inside
+a comment,
+or a single or double quote.
+Parsing for quotes is very simplistic:
+when it finds an open quote,
+it ignores everything (except escaped quotes)
+until it finds a close quote, and
+it will not complain if it gets
+to the end of a line and finds no backslash for continuation.
+.Pp
+Available options:
+.Bl -tag -width Ds -compact
+.It Fl D Ns Ar sym
+.It Fl U Ns Ar sym
+Specify which symbols to define or undefine.
+and the lines inside those ifdefs will be copied to the output or removed as
+appropriate.
+The ifdef, ifndef, else, and endif lines associated with
+.Ar sym
+will also be removed.
+Ifdefs involving symbols you don't specify
+and ``#if'' control lines
+are untouched and copied out
+along with their associated
+ifdef, else, and endif lines.
+If an ifdef X occurs nested inside another ifdef X, then the
+inside ifdef is treated as if it were an unrecognized symbol.
+If the same symbol appears in more than one argument,
+the last occurrence dominates.
+.Pp
+.It Fl c
+If the
+.Fl c
+flag is specified,
+then the operation of
+.Nm unifdef
+is complemented,
+i.e. the lines that would have been removed or blanked
+are retained and vice versa.
+.Pp
+.It Fl l
+Replace removed lines with blank lines
+instead of deleting them.
+.It Fl t
+Disables parsing for
+C comments and quotes useful for plain text
+(not C code).
+.Pp
+.It Fl iD Ns Ar sym
+.It Fl iU Ns Ar sym
+Ignore ifdefs.
+If your C code uses ifdefs to delimit non-C lines,
+such as comments
+or code which is under construction,
+then you must tell
+.Nm unifdef
+which symbols are used for that purpose so that it won't try to parse
+for quotes and comments
+inside those ifdefs.
+One specifies ignored ifdefs with
+.Fl iD Ns Ar sym
+and
+.Fl iU Ns Ar sym
+similar to
+.Fl D Ns Ar sym
+and
+.Fl U Ns Ar sym
+above.
+.El
+.Pp
+.Nm Unifdef
+copies its output to
+.Em stdout
+and will take its input from
+.Em stdin
+if no
+.Ar file
+argument is given.
+.Pp
+.Nm Unifdef
+works nicely with the
+.Fl D Ns Ar sym
+option added to
+.Xr diff 1
+as of the 4.1 Berkeley Software Distribution.
+.Sh SEE ALSO
+.Xr diff 1
+.Sh DIAGNOSTICS
+Inappropriate else or endif.
+.br
+Premature
+.Tn EOF
+with line numbers of the unterminated #ifdefs.
+.Pp
+Exit status is 0 if output is exact copy of input, 1 if not, 2 if trouble.
+.Sh BUGS
+Should try to deal with ``#if'' lines.
+.Pp
+Doesn't work correctly if input contains null characters.
+.Sh HISTORY
+The
+.Nm
+command appeared in
+.Bx 4.3 .
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