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I tried to find the default include path of the C compiler in Mac OS X (Mavericks) by using gcc -v:

$ gcc -v
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/c++/4.2.1
Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)
Target: x86_64-apple-darwin13.0.0
Thread model: posix

It seems to tell me the path is /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/c++/4.2.1, but I'm afraid it is not the true path. I think the true path for including standard C library is /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include because <sys/syscall.h> locates in the later path, which is /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/sys/syscall.h

Does anyone have ideas about how to view all the default include path of C library in Mac OS X?

Hanfei Sun
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1 Answers1

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You need to ask the preprocessor, not gcc, for telling the default include path.

You can say:

`gcc -print-prog-name=cc1` -v

In order to list default include path for both C and C++:

`gcc -print-prog-name=cc1plus` -v

(The path that you've listed above is the one that was used to configure GCC while building.)

Another way to list the default include path would be:

gcc -x c -v -E /dev/null

gcc -x c++ -v -E /dev/null     # (for C/C++)
devnull
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    That doesn't work on OS X Mavericks (Xcode 5) since `gcc` actually invokes `cc` which is `clang`. And they all return `cc1` which doesn't actually exist. – Ned Deily Nov 08 '13 at 06:12
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    I tried your ways and found that only `gcc -x c++ -v -E /dev/null` works for Mac OS 10.12.5. – Robert Oct 10 '17 at 14:49