Header absolute paths for GCC

Question

I am looking to print a list of absolute paths to a specific header file used by gcc without compiling anything (or specifying a particular compile target, like with gcc -M). E.g., the following would print a list of absolute paths with all matches for limits.h found in the appropriate directories:

gcc <flag/command> limits.h

A (non-)solution that returns only working header files is to simply create a check.c, #include all desired header names there, and run gcc -M check.c.

Another solution, (albeit using bash stuff) is found in this answer and here.

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Related questions that didn't quite have what I want:

• How can I see the location of a header included with #include?
• Where does gcc look for C and C++ header files?
• How to I find the filename of a library via the library name?
• How can I find the full file path given a library name like libfoo.so.1?
• gcc -print-file-name=libc.a prints absolute path in the strange form

Answer 1

It looks like you could use this answer and a little shell scripting to do what you want; e.g:

$ gcc -xc -E -v - < /dev/null 2>&1 |
  sed -n '/#include <...>/,/End of search list/ {/#include/d; /End/d; p};' |
  xargs -IPATH find PATH -name limits.h
/usr/lib/gcc/x86_64-redhat-linux/14/include/limits.h
/usr/include/c++/14/tr1/limits.h
/usr/include/linux/limits.h
/usr/include/limits.h

Or alternatively, maybe something like this:

$ echo '#include <limits.h>' | gcc -E - | grep '/limits.h' | cut -f2 -d'"' | sort -u
/usr/include/limits.h
/usr/include/linux/limits.h
/usr/lib/gcc/x86_64-redhat-linux/14/include/limits.h