Include Linux header file

Question

How could I include a linux header file? I read from the web that the header file is in /usr/include. However, the header file I need is not in that directory; it is in /usr/src/kernels/2.6.32.../include/linux/.

I tried to include the file using the full path. However, the file itself includes other header files as well. Hence, the compiler couldn't find the other header files when I compile.

How could I include the header file in my program and compile the program?

Answer 1

If you are on Ubuntu, install libcpufreq-dev. This will give you the cpufreq.h header at /usr/include/cpufreq.h, which you can include from your code with #include <cpufreq.h>.

Answer 2

By default, gcc searches the following directories for header files:

/usr/local/include/
/usr/include/

and the following directories for libraries:

/usr/local/lib/
/usr/lib/

The compiler options -I and -L add new directories to the beginning of the include path and library search path respectively.