How can I add a default include path for GCC in Linux?

I’d like GCC to include files from $HOME/include in addition to the usual include directories, but there doesn’t seem to be an analogue to $LD_LIBRARY_PATH.

I know I can just add the include directory at command line when compiling (or in the makefile), but I’d really like a universal approach here, as in the library case.

Answer

Try setting C_INCLUDE_PATH (for C header files) or CPLUS_INCLUDE_PATH (for C++ header files) environment variables.

As Ciro mentioned, CPATH will set the path for both C and C++ (and any other language).

On Windows these may be set to semicolon-separated lists. On most other platforms they may be set to colon-separated lists.

More details in GCC’s documentation.