unifdef - Removes #ifdefed lines
unifdef [-tlc] [-Dsymbol] [-idsymbol] [-iusymbol] [file]
[-Usymbol]
The unifdef command partially simulates the behavior of
the C preprocessor in processing #ifdef conditionals.
Complements the action of unifdef; retains lines that
would normally be removed and removes lines that would
normally be retained. Specifies symbol as a defined
#ifdef symbol. Specifies defined lines inside certain
#ifdefs to be ignored but copied out. Specifies undefined
lines inside certain #ifdefs to be ignored and not copied
out. Replaces removed lines with blank lines instead of
deleting them. Processes plain text (rather than C code)
input. The unifdef command does not try to recognize comments,
single quotes, and double quotes. Specifies symbol
as an undefined #ifdef symbol.
The unifdef command recognizes nested #ifdefs, comments,
single and double quotes of C syntax so that it can function
correctly, but does not include files or interpret
macros. The unifdef command recognizes, but does not
remove comments.
The unifdef command takes its input from stdin if no file
argument is given, and copies its output to stdout.
You specify the symbols you want defined with -Dsymbol or
undefined with -Usymbol and the lines inside those #ifdefs
are copied to the output or removed, as appropriate. The
#ifdef, #ifndef, #else, #elif, and endif lines associated
with symbol are also removed. The #ifdefs involving
unspecified symbols are untouched and copied out along
with their associated #ifdef, #else, elif, and #endif
lines. If the same symbol appears in more than one argument,
only the first occurrence is significant. For
instance, if an #ifdef X occurs nested inside another
#ifdef X, the inside #ifdef is considered an unrecognized
symbol.
If you use #ifdefs to delimit non-C lines, such as comments
or unfinished code, it is necessary to specify which
symbols are to be used for that purpose. Otherwise, the
unifdef command tries to parse for quotes and comments in
those #ifdef lines.
Keywords [Toc] [Back]
The following keywords can be used with the unifdef command:
ifdef ifndef else endif elif
The unifdef command uses the elif keyword as follows.
(Note that "Understood" means unifdef knows how to convert
elif to if.) Understood Not understood Not understood
For example:
# ifdef X x # elif defined (Y) y # elif defined (A) ||
defined (B) a # else default # endif
The following list shows the results of using the elif
keyword with variables:
-DX x
-UX # if defined (Y) y # elif defined (A) || defined (B)
a # else default # endif -UX -DY y
-UY -UX # if defined (Y) y # elif defined (A) || defined
(B) a # else default # endif
-UY -UX -DA # if defined (Y) y # elif defined (A) ||
defined (B) a # else default # endif
The unifdef command cannot process cpp constructs such as:
#if defined(X) || defined(Y)
The unifdef command can fail for several reasons: a premature
end of file, or an inappropriate else, elif, or
endif.
Exit status is 0 if output is an exact copy of input, 1 if
not, 2 if the unifdef command fails.
The following command line causes the unifdef command to
read the file original.c and remove the #ifdef A lines.
It then removes everything following an #elif/#else associated
with the #ifdef A down to the #endif: unifdef -DA
original.c > modified.c The following command line causes
the unifdef command to read the file original.c, and
remove the #ifdef A down to either its associated
#elif/#else, or its associated #endif: unifdef -UA original.c
> modified.c
In the case of the #elif, the #elif is replaced
with #if. In the case of #else, the #else is
deleted along with its associated #endif.
Commands: diff(1)
unifdef(1)
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