minix man page for ifdef

IFDEF(1)						      General Commands Manual							  IFDEF(1)

NAME
       ifdef - remove #ifdefs from a file

SYNOPSIS
       ifdef [-t] [-dsymbol] [-Dsymbol] [-Usymbol] [-Isymbol] [file]

OPTIONS
       -D     Define symbol permanently

       -I     Ignore symbol

       -U     Undefine symbol permanently

       -d     Define symbol. It may be #undef'ed later

       -t     Produce a table of the symbols on stdout

EXAMPLES
       ifdef -DUNIX file.c >newfile.c
			   # Define UNIX

       ifdef -D_MINIX -UDOS <x.c >y.c
			   # Define

DESCRIPTION
       Ifdef  allows  conditional code [ #ifdef ... #endif ] to be selectively removed from C files, but at the same time leaving all other C pre-
       processor commands intact such as #define, #include etc.  Input to ifdef is either the file named as the last argument, or stdin if no file
       is named.  Output goes to stdout.

       Symbols	may be defined with the -d or -D flags just like cpp, except that the latter option ignores subsequent #undefs.  It is not permit-
       ted to give values to symbols.  Similarly, -U undefines a symbol and ignores subsequent #definess.  Symbols defined with  -I  are  ignored;
       any #ifdef using an ignored symbol will be left intact.

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