轉自：

方法：

對於C

C_INCLUDE_PATH=/new/include/dir 
export C_INCLUDE_PATH

對於C++

CPLUS_INCLUDE_PATH=/new/include/dir 
export CPLUS_INCLUDE_PATH

檢視新增結果：

對於C

echo | gcc -v -x c++ -E -

對於C++

echo | g++ -v -x c++ -E -

執行後會看到類似下面的結果，藍色標記的是新新增的include路徑

Using built-in specs.
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib --with-ppl --with-cloog --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
gcc version 4.4.6 20120305 (Red Hat 4.4.6-4) (GCC)
COLLECT_GCC_OPTIONS='-v' '-E' '-shared-libgcc' '-mtune=generic'
 /usr/libexec/gcc/x86_64-redhat-linux/4.4.6/cc1plus -E -quiet -v -D_GNU_SOURCE - -mtune=generic
ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/4.4.6/include-fixed"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../x86_64-redhat-linux/include"
#include "..." search starts here:
#include <...> search starts here:
 /new/include/dir

 /usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6
 /usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/x86_64-redhat-linux
 /usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/backward
 /usr/local/include
 /usr/lib/gcc/x86_64-redhat-linux/4.4.6/include
 /usr/include
End of search list.
# 1 "<stdin>"
# 1 "<built-in>"
# 1 "<command-line>"
# 1 "<stdin>"
COMPILER_PATH=/usr/libexec/gcc/x86_64-redhat-linux/4.4.6/:/usr/libexec/gcc/x86_64-redhat-linux/4.4.6/:/usr/libexec/gcc/x86_64-redhat-linux/:/usr/lib/gcc/x86_64-redhat-linux/4.4.6/:/usr/lib/gcc/x86_64-redhat-linux/:/usr/libexec/gcc/x86_64-redhat-linux/4.4.6/:/usr/libexec/gcc/x86_64-redhat-linux/:/usr/lib/gcc/x86_64-redhat-linux/4.4.6/:/usr/lib/gcc/x86_64-redhat-linux/
LIBRARY_PATH=/usr/lib/gcc/x86_64-redhat-linux/4.4.6/:/usr/lib/gcc/x86_64-redhat-linux/4.4.6/:/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../lib64/:/lib/../lib64/:/usr/lib/../lib64/:/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-E' '-shared-libgcc' '-mtune=generic'

注意：

該方法只對當前ssh session有效，重新連線後，新加的include路徑，gcc/g++將不儲存