freebsd-skq/usr.bin/unifdef/unifdef.1

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.\" 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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.\"     @(#)unifdef.1	8.2 (Berkeley) 4/1/94
.\"	$dotat: things/unifdef.1,v 1.25 2002/09/24 19:16:29 fanf2 Exp $
.\" $FreeBSD$
.\"
.Dd September 24, 2002
.Dt UNIFDEF 1
.Os
.Sh NAME
.Nm unifdef , unifdefall
.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
.Nm unifdefall
.Op Fl I Ns Ar path
.Ar ...
.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.
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
are handled,
and anything more complicated is passed through unharmed.
.Ic #ifdef
and
.Ic #ifndef
directives are only processed
if the symbol is specified on the command line,
otherwise they are also passed through unchanged.
Constant
.Ic #if
and
.Ic #elif
expressions are passed through by default,
or they may be processed by specifying the
.Fl k
flag.
.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
A script called
.Nm unifdefall
can be used to remove all conditional
.Xr cpp 1
directives from a file.
It uses
.Nm Fl s
and
.Nm cpp Fl dM
to get lists of all the controlling symbols
and their definitions (or lack thereof),
then invokes
.Nm
with appropriate arguments to process the file.
.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.
.Pp
.It Fl I Ns Ar path
Specifies to
.Nm unifdefall
an additional place to look for
.Ic #include
files.
This option is ignored by
.Nm
for compatibility with
.Xr cpp 1
and to simplify the implementation of
.Nm unifdefall .
.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 .