Linux 学习笔记--碎片

1、include search path
By default, the preprocessor looks for header files included by the quote form of the directive #include "file" first relative to the directory of the current file, and then in a preconfigured list of standard system directories. For example, if /usr/include/sys/stat.h contains #include "types.h", GCC looks for types.h first in /usr/include/sys, then in its usual search path.

For the angle-bracket form #include , the preprocessor’s default behavior is to look only in the standard system directories. The exact search directory list depends on the target system, how GCC is configured, and where it is installed. You can find the default search directory list for your version of CPP by invoking it with the -v option.

For example, on tx2

shell: cpp -v /dev/null -o /dev/null

#include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/aarch64-linux-gnu/5/include
 /usr/local/include
 /usr/lib/gcc/aarch64-linux-gnu/5/include-fixed
 /usr/include/aarch64-linux-gnu
 /usr/include
End of search list.