.\"	$OpenBSD: unifdef.1,v 1.10 2002/12/02 07:18:50 deraadt Exp $
.\" Copyright (c) 1985, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Dave Yost. Support for #if and #elif was added by Tony Finch.
.\"
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.\" modification, are permitted provided that the following conditions
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.\"    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.
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\"     @(#)unifdef.1	8.2 (Berkeley) 4/1/94
.\"	$dotat: things/unifdef.1,v 1.26 2002/09/24 19:44:12 fanf2 Exp $
.\" $FreeBSD: src/usr.bin/unifdef/unifdef.1,v 1.15 2002/09/24 19:48:39 fanf Exp $
.\"
.Dd September 24, 2002
.Dt UNIFDEF 1
.Os
.Sh NAME
.Nm unifdef
.Nd remove preprocessor conditionals from code
.Sh SYNOPSIS
.Nm
.Op Fl cklst
.Oo
.Fl I Ns Ar path
.Fl D Ns Ar sym
.Ns Op = Ns Ar val
.Fl U Ns Ar sym
.Fl iD Ns Ar sym
.Ns Op = Ns Ar val
.Fl iU Ns Ar sym
.Oc
.Ar ...
.Op Ar file
.Sh DESCRIPTION
The
.Nm
utility selectively processes conditional
.Xr cpp 1
directives.
It removes from a file
both the directives
and any additional text that they specify should be removed,
while otherwise leaving the file alone.
.Pp
The
.Nm
utility acts on
.Ic #if , #ifdef , #ifndef , #elif , #else ,
and
.Ic #endif
lines,
and it understands only the commonly-used subset
of the expression syntax for
.Ic #if
and
.Ic #elif
lines.
It handles
integer values of symbols defined on the command line,
the
.Fn defined
operator applied to symbols defined or undefined on the command line,
the operators
.Ic \&! , < , > , <= , >= , == , != , && , || ,
and parenthesized expressions.
Anything that it does not understand is passed through unharmed.
It only processes
.Ic #ifdef
and
.Ic #ifndef
directives if the symbol is specified on the command line,
otherwise they are also passed through unchanged.
By default, it ignores
.Ic #if
and
.Ic #elif
lines with constant expressions,
or they may be processed by specifying the
.Fl k
flag on the command line.
.Pp
The
.Nm
utility also understands just enough about C
to know when one of the directives 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 indent -compact
.It Fl D Ns Ar sym
.Ns Op = Ns Ar val
Specify that a symbol is defined,
and optionally specify what value to give it
for the purpose of handling
.Ic #if
and
.Ic #elif
directives.
.Pp
.It Fl U Ns Ar sym
Specify that a symbol is undefined.
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
is complemented,
i.e., the lines that would have been removed or blanked
are retained and vice versa.
.Pp
.It Fl k
Process
.Ic #if
and
.Ic #elif
lines with constant expressions.
By default, sections controlled by such lines are passed through unchanged
because they typically start
.Li #if 0
and are used as a kind of comment to sketch out future or past development.
It would be rude to strip them out, just as it would be for normal comments.
.Pp
.It Fl l
Replace removed lines with blank lines
instead of deleting them.
.Pp
.It Fl s
Instead of processing the input file as usual,
this option causes
.Nm
to produce a list of symbols that appear in expressions
that
.Nm
understands.
It is useful in conjunction with the
.Fl dM
option of
.Xr cpp 1
for creating
.Nm
command lines.
.Pp
.It Fl t
Disables parsing for C comments and quotes, which is useful
for plain text.
.Pp
.It Fl iD Ns Ar sym
.Ns Op = Ns Ar val
.It Fl iU Ns Ar sym
Ignore
.Ic #ifdef Ns s .
If your C code uses
.Ic #ifdef Ns s
to delimit non-C lines,
such as comments
or code which is under construction,
then you must tell
.Nm
which symbols are used for that purpose so that it will not try to parse
for quotes and comments
inside those
.Ic #ifdef Ns s .
One specifies ignored symbols with
.Fl iD Ns Ar sym
.Ns Oo = Ns Ar val Oc
and
.Fl iU Ns Ar sym
similar to
.Fl D Ns Ar sym
.Ns Op = Ns Ar val
and
.Fl U Ns Ar sym
above.
.El
.Pp
The
.Nm
utility copies its output to
.Em stdout
and will take its input from
.Em stdin
if no
.Ar file
argument is given.
.Pp
The
.Nm
utility works nicely with the
.Fl D Ns Ar sym
option of
.Xr diff 1 .
.Sh SEE ALSO
.Xr cpp 1 ,
.Xr diff 1
.Sh DIAGNOSTICS
.Bl -item
.It
Inappropriate elif, else or endif.
.It
Premature
.Tn EOF
with line numbers of the unterminated
.Ic #ifdef Ns s .
.El
.Pp
The
.Nm
utility exits 0 if the output is an exact copy of the input,
1 if not, and 2 if in trouble.
.Sh BUGS
Expression evaluation is very limited.
.Pp
Does not work correctly if input contains nul characters.
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.3 .