系统:CentOS-6.5-x86_64-minimal
为了使用c++11特性，升级gcc.
wget http://ftp.tsukuba.wide.ad.jp/software/gcc/releases/gcc-4.9.2/gcc-4.9.2.tar.bz2 tar -xjvf gcc-4.9.2.tar.bz2 cd gcc-4.9.2.tar.bz2 ./configure
wget下载慢，服务器也是日本的，可以用QQ旋风或迅雷下载，再psftp上传，
出现错误:
configure: error: Building GCC requires GMP 4.2+, MPFR 2.4.0+ and MPC 0.8.0+. Try the --with-gmp, --with-mpfr and/or --with-mpc options to specify their locations. Source code for these libraries can be found at their respective hosting sites as well as at ftp://gcc.gnu.org/pub/gcc/infrastructure/.
安装gmp、mpfr、mpc
下载地址：
http://ftp.tsukuba.wide.ad.jp/software/gcc/infrastructure/gmp-4.3.2.tar.bz2 http://ftp.tsukuba.wide.ad.jp/software/gcc/infrastructure/mpfr-2.4.2.tar.bz2 http://ftp.tsukuba.wide.ad.jp/software/gcc/infrastructure/mpc-0.8.1.tar.gz
解压后逐个安装，
./configure
make
make install
再次错误，
The following languages will be built: c,c++,fortran,java,lto,objc *** This configuration is not supported in the following subdirectories: gnattools target-libada target-libgo target-libbacktrace (Any other directories should still work fine.) checking for default BUILD_CONFIG... bootstrap-debug checking for --enable-vtable-verify... no /usr/bin/ld: crt1.o: No such file: No such file or directory collect2: ld returned 1 exit status configure: error: I suspect your system does not have 32-bit developement libraries (libc and headers).
If you have them, rerun configure with --enable-multilib.
If you do not have them, and want to build a 64-bit-only compiler, rerun configure with --disable-multilib.
系统没有32位开发支持库,可以运行yum install glibc-devel.i686安装，不过我这里不需要编译32位程序，直接
./configure --disable-multilib
这回配置完成，
make
出现错误，
checking whether build environment is sane... configure: error: newly created file is older than distributed files! Check your system clock make[2]: *** [configure-stage1-zlib] Error 1 make[2]: Leaving directory `/root/gcc-4.9.2' make[1]: *** [stage1-bubble] Error 2 make[1]: Leaving directory `/root/gcc-4.9.2' make: *** [all] Error 2
更新时间，
ntpdate cn.pool.ntp.org
继续
make
约半小时后，出现错误，
checking for suffix of object files... configure: error: in `/root/gcc-4.9.2/x86_64-unknown-linux-gnu/libgcc': configure: error: cannot compute suffix of object files: cannot compile See `config.log' for more details. make[2]: *** [configure-stage1-target-libgcc] Error 1 make[2]: Leaving directory `/root/gcc-4.9.2' make[1]: *** [stage1-bubble] Error 2 make[1]: Leaving directory `/root/gcc-4.9.2' make: *** [all] Error 2
查看config.log，发现在配置libgcc时出错了，yum list libgcc，发现已安装libgcc.x86_64，难道要装i686的？go~
yum install libgcc.i686
继续
make
约四小时这样子就编译完成了,
make install
几分钟就安装完成。
看效果
gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-unknown-linux-gnu/4.9.2/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: ./configure --disable-multilib Thread model: posix gcc version 4.9.2 (GCC)