unifdef(1)						      General Commands Manual							unifdef(1)

NAME

       unifdef - Removes #ifdefed lines

SYNOPSIS

       unifdef [-tlc] [-Dsymbol] [-idsymbol] [-iusymbol] [file] [-Usymbol]

       The unifdef command partially simulates the behavior of the C preprocessor 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.  Speci-
       fies 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.  Pro-
       cesses 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 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
       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

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  every-
       thing  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)