Hey Song, first of all, please always include the gcc-help mailing list in your replies > Seems the pipe [echo "" | gcc ] not been recognized by gcc as a valid input. Tried [touch tmp.c] then [gcc -xc -c -v tmp.c -o tmp.o], and it works. Yep, that's the alternative to do it in two steps > A curious question, actually 2: > 1. why search /usr/local/include before /usr/include? > 2. What is the intention of having a /usr/local in case we already have /usr to install all "user-specific-packages"? The /usr/local hierarchie is usually used to install 'local' programs meaning programs which aren't deployed by the distribution's package manager. Or said differently, self-compiled programs. I assume the /usr/local/include has been added to gcc's search paths to allow system administrators to easily overwrite the default include headers (available in /usr/include), e.g. for testing/debugging purpose. Why are you asking? Just for interest, or do you have any problems with the include search paths? Andi > > Best Regards, > > Song Du > > Application Processor System Engineering @ Marvell Technology Shanghai Ltd. > > -----Original Message----- > From: Andi Hellmund [mailto:mail@xxxxxxxxxxxxxxxx] > Sent: 2010Äê5ÔÂ17ÈÕ 20:57 > To: Song Du > Cc: mail@xxxxxxxxxxxxxxxx > Subject: RE: when GCC searches the system include directories, "/usr/include" first, or "usr/lib/gcc/include", "usr/local/lib/gcc/include" first? > > Hey Song, > >> For example, the GCC -v option copied from my Ubuntu desktop: >> Target: i486-linux-gnu >> Configured with: ../src/configure -v --with-pkgversion='Ubuntu >> 4.4.1-4ubuntu9' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs >> --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr > > Right, by using the -v option without any input files, you get only the > options passed to the configure script. [The --prefix option dictates > where the finaly executables will be installed to] > > Just try: > > # echo "" | gcc -c -v -x c - -o tmp.o > > #include "..." search starts here: > #include <...> search starts here: > /usr/local/include > /usr/lib/gcc/x86_64-unknown-linux-gnu/4.4.3/include > /usr/lib/gcc/x86_64-unknown-linux-gnu/4.4.3/include-fixed > /usr/include > > > @ALL: I'll add this type of question to the wiki-FAQ > > Best regards, > Andi
