unifdef(1)unifdef(1)NAMEunifdef - Removes #ifdefed lines
SYNOPSISunifdef [-tlc] [-Dsymbol] [-idsymbol] [-iusymbol] [file] [-Usymbol]
The unifdef command partially simulates the behavior of the C pre‐
processor in processing #ifdef conditionals.
OPTIONS
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 cer‐
tain #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.
DESCRIPTION
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 out‐
put 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 unfin‐
ished 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
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.) Under‐
stood 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
NOTES
The unifdef command cannot process cpp constructs such as:
#if defined(X) || defined(Y)DIAGNOSTICS
The unifdef command can fail for several reasons: a premature end of
file, or an inappropriate else, elif, or endif.
EXIT STATUS
Exit status is 0 if output is an exact copy of input, 1 if not, 2 if
the unifdef command fails.
EXAMPLES
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.
SEE ALSO
Commands: diff(1)unifdef(1)
