UNIFDEF(1) BSD General Commands Manual UNIFDEF(1)NAMEunifdef — remove ifdef'ed lines
SYNOPSISunifdef [-clt] [-Dsym -Usym -iDsym -iDsym] ... [file]
Unifdef is useful for removing ifdef'ed lines from a file while otherwise
leaving the file alone. Unifdef acts on #ifdef, #ifndef, #else, and
#endif lines, and it knows only enough about C to know when one of these
is inactive because it is inside a comment, or a single or double quote.
Parsing for quotes is very simplistic: when it finds an open quote, it
ignores everything (except escaped quotes) until it finds a close quote,
and it will not complain if it gets to the end of a line and finds no
backslash for continuation.
-Usym Specify which symbols to define or undefine. 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 and ``#if'' control lines 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, the last occur‐
-c If the -c flag 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.
-l Replace removed lines with blank lines instead of deleting them.
-t Disables parsing for C comments and quotes, which is useful for
-iUsym Ignore ifdefs. If your C code uses ifdefs to delimit non-C
lines, such as comments or code which is under construction, then
you must tell unifdef which symbols are used for that purpose so
that it won't try to parse for quotes and comments inside those
ifdefs. One specifies ignored ifdefs with -iDsym and -iUsym sim‐
ilar to -Dsym and -Usym above.
Unifdef copies its output to stdout and will take its input from stdin if
no file argument is given.
Unifdef works nicely with the -Dsym option added to diff(1) as of the 4.1
Berkeley Software Distribution.
Inappropriate else or endif.
Premature EOF with line numbers of the unterminated #ifdefs.
Exit status is 0 if output is exact copy of input, 1 if not, 2 if trou‐
Should try to deal with ``#if'' lines.
Doesn't work correctly if input contains null characters.
The unifdef command appeared in 4.3BSD.
4.3 Berkeley Distribution April 1, 1994 4.3 Berkeley Distribution