unifdef - remove ifdef'ed lines
unifdef [ -t -l -c -Dsym -Usym -idsym -iusym ] ... [ file ]
Unifdef is useful for removing ifdef'ed lines from a file while otherwise leaving the file
alone. Unifdef is like a stripped-down C preprocessor: it is smart enough to deal with
the nested ifdefs, comments, single and double quotes of C syntax so that it can do its
job, but it doesn't do any including or interpretation of macros. Neither does it strip
out comments, though it recognizes and ignores them. You specify which symbols you want
defined -Dsym or undefined -Usym and the lines inside those ifdefs will be copied to the
output or removed as appropriate. The ifdef, ifndef, else, and endif lines associated
with sym will also be removed. Ifdefs involving symbols you don't specify are untouched
and copied out along with their associated ifdef, else, and endif lines. If an ifdef X
occurs nested inside another ifdef X, then the inside ifdef is treated as if it were an
unrecognized symbol. If the same symbol appears in more than one argument, only the first
occurrence is significant.
The -l option causes unifdef to replace removed lines with blank lines instead of deleting
If you use ifdefs to delimit non-C lines, such as comments or code which is under con-
struction, then you must tell unifdef which symbols are used for that purpose so that it
won't try to parse for quotes and comments in those ifdef'ed lines. You specify that you
want the lines inside certain ifdefs to be ignored but copied out with -idsym and -iusym
similar to -Dsym and -Usym above.
If you want to use unifdef for plain text (not C code), use the -t option. This makes
unifdef refrain from attempting to recognize comments and single and double quotes.
Unifdef copies its output to stdout and will take its input from stdin if no file argument
is given. If the -c argument 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.
Premature EOF, inappropriate else or endif.
Exit status is 0 if output is exact copy of input, 1 if not, 2 if trouble.
Does not know how to deal with cpp consructs such as
#if defined(X) || defined(Y)
4.3 Berkeley Distribution April 29, 1985 UNIFDEF(1)