ifdef.1

Unix操作系统minix 2.0源码

.TH IFDEF 1
.SH NAME
ifdef \- remove #ifdefs from a file
.SH SYNOPSIS
\fBifdef \fR[\fB\-t\fR] [\fB\-d\fIsymbol\fR] [\fB\-D\fIsymbol\fR] [\fB\-U\fIsymbol\fR] [\fB\-I\fIsymbol\fR] [file]\fR
.br
.de FL
.TP
\\fB\\$1\\fR
\\$2
..
.de EX
.TP 20
\\fB\\$1\\fR
# \\$2
..
.SH OPTIONS
.FL "\-D" "Define symbol permanently"
.FL "\-I" "Ignore symbol"
.FL "\-U" "Undefine symbol permanently"
.FL "\-d" "Define symbol. It may be #undef'ed later"
.FL "\-t" "Produce a table of the symbols on \fIstdout\fR"
.SH EXAMPLES
.EX "ifdef \-DUNIX file.c >newfile.c" "Define \fIUNIX\fR"
.EX "ifdef \-D_MINIX \-UDOS <x.c >y.c "Define \fI_MINIX\fR, undefine \fIDOS\fR"
.SH DESCRIPTION
.PP
\fIIfdef\fR
allows conditional code [ #ifdef ... #endif ]
to be selectively removed from C files, but at the same time leaving
all other C preprocessor commands intact such as #define, #include etc.
Input to
.I ifdef
is either the file named as the last argument, or \fIstdin\fR if no file
is named.
Output goes to \fIstdout\fR.
.PP
Symbols may be defined with the \fB\-d\fR or \fB\-D\fR flags just like
\fIcpp\fR, except that the latter option ignores subsequent \fI#undefs\fR.
It is not permitted to give values to symbols.
Similarly, \fB\-U\fR undefines a symbol and ignores subsequent 
\fI#defines\fRs.
Symbols defined with \fB\-I\fR are ignored; any \fI#ifdef\fR using an
ignored symbol will be left intact.