| UNIFDEF(1) | General Commands Manual | UNIFDEF(1) |
unifdef, unifdefall —
unifdef |
[-ceklst]
[-Ipath]
[-Dsym[=val]]
[-Usym]
[-iDsym[=val]]
[-iUsym]
... [-o
output] [file] |
unifdefall |
[-Ipath]
... file |
unifdef utility selectively processes conditional
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.
The unifdef utility acts on
#if, #ifdef,
#ifndef, #elif,
#else, and #endif lines, and
it understands only the commonly-used subset of the expression syntax for
#if and #elif lines. It
handles integer values of symbols defined on the command line, the
defined() operator applied to symbols defined or
undefined on the command line, the operators !,
<, >,
<=, >=,
==, !=,
&&, ||, and
parenthesized expressions. Anything that it does not understand is passed
through unharmed. It only processes #ifdef and
#ifndef directives if the symbol is specified on the
command line, otherwise they are also passed through unchanged. By default,
it ignores #if and #elif
lines with constant expressions, or they may be processed by specifying the
-k flag on the command line.
The unifdef utility also understands just
enough about C to know when one of the directives is inactive because it is
inside a comment, or affected by a backslash-continued line. It spots
unusually-formatted preprocessor directives and knows when the layout is too
odd to handle.
A script called unifdefall can be used to
remove all conditional cpp(1)
directives from a file. It uses unifdef
-s and cpp
-dM to get lists of all the controlling symbols and
their definitions (or lack thereof), then invokes
unifdef with appropriate arguments to process the
file.
Available options:
-Dsym[=val]#if and
#elif directives.-Usym-c-c flag is specified, then the operation of
unifdef is complemented, i.e., the lines that
would have been removed or blanked are retained and vice versa.-eunifdef processes its input one line at a
time, it cannot remove preprocessor directives that span more than one
line. The most common example of this is a directive with a multi-line
comment hanging off its right hand end. By default, if
unifdef has to process such a directive, it will
complain that the line is too obfuscated. The -e
option changes the behaviour so that, where possible, such lines are left
unprocessed instead of reporting an error.-k#if and #elif
lines with constant expressions. By default, sections controlled by such
lines are passed through unchanged because they typically start
“#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.-l-o
output-sunifdef to produce a list of symbols that appear
in expressions that unifdef understands. It is
useful in conjunction with the -dM option of
cpp(1) for creating
unifdef command lines.-t-iDsym[=val]-iUsym#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
unifdef which symbols are used for that purpose so
that it will not try to parse comments and line continuations inside those
#ifdefs. One specifies ignored symbols with
-iDsym[=val]
and -iUsym similar to
-Dsym[=val]
and -Usym above.-Ipathunifdefall an additional place to
look for #include files. This option is ignored by
unifdef for compatibility with
cpp(1) and to simplify the
implementation of unifdefall.The unifdef utility copies its output to
stdout and will take its input from
stdin if no file argument is
given.
The unifdef utility works nicely with the
-Dsym option of
diff(1).
#elif, #else
or #endif.EOF (with the line number of the most
recent unterminated #if).EOF
in comment.The unifdef utility exits 0 if the output
is an exact copy of the input, 1 if not, and 2 if in trouble.
unifdef command appeared in
4.3BSD. ANSI C support was added in
FreeBSD 4.7.
Preprocessor control lines split across more than one physical line (because of comments or backslash-newline) cannot be handled in every situation.
Trigraphs are not recognized.
There is no support for symbols with different definitions at different points in the source file.
The text-mode and ignore functionality does not correspond to modern cpp(1) behaviour.
| June 5, 2009 | NetBSD 9.2 |