给公司测试服务器搭环境，手工安装gcc-4.9.0颇费功夫，记录如下。
1、安装gcc、g++，系统源默认安装版本为4.4.7；
2、安装依赖包GMP、MPFR、MPC，注意安装顺序；
3、修改动态库链接路径，加入GMP、MPFR、MPC;
4、编译安装Gcc-4.9，新创建目录gcc-build来存放Make过程产生文件；
5、拷贝Gcc-4.9的头文件至目录/usr/include/c++；
6、修改LD_LIBRARY_PATH、PATH和CPLUS_INCLUDE_PATH，保存到/etc/profile；
7、建立新的Gcc、G++软连接。
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yum -y install gcc
yum -y install gcc-c++
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mkdir /usr/local/gmp-4.3.
./configure --prefix=/usr/local/gmp-4.3./
make
make install mkdir /usr/local/mpfr-2.4.
./configure --prefix=/usr/local/mpfr-2.4. --with-gmp=/usr/local/gmp-4.3.
make
make install mkdir /usr/local/mpc-0.8.
./configure --prefix=/usr/local/mpc-0.8. --with-gmp=/usr/local/gmp-4.3. --with-mpfr=/usr/local/mpfr-2.4.
make
make install
、
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/gmp-4.3./lib:/usr/local/mpfr-2.4./lib:/usr/local/mpc-0.8./lib
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mkdir gcc-bulid
cd gcc-build
../gcc-4.9./configure --prefix=/usr/local/gcc-4.9. --exec-prefix=/usr/local/gcc --enable-languages=c,c++ --with-gmp=/usr/local/gmp-4.3. --with-mpfr=/usr/local/mpfr-2.4. --with-mpc=/usr/local/mpc-0.8. --disable-multilib
make
make install
、
cp -r /usr/local/gcc-4.9./include/c++/4.9. /usr/include/c++
、
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/gmp-4.3./lib:/usr/local/mpfr-2.4./lib:/usr/local/mpc-0.8./lib:/usr/local/gcc/lib64
export PATH=$PATH:/usr/local/gcc/bin
export CPLUS_INCLUDE_PATH=$CPLUS_INCLUDE_PATH:/usr/include/c++/4.9.:/usr/include/c++/4.9./x86_64-unknown-linux-gnu
、
mv gcc gcc-4.4.
ln -s /usr/local/gcc/bin/gcc ./gcc mv g++ g++-4.4.
ln -s /usr/local/gcc/bin/g++ g++