tab键：
CentOS7系统tab命令补全
bash-completion
在新安装的CentOS7系统中，如果没有安装命令补全的话，在systemctl管理服务的时候就没法用tab来自动补全，因此在安装完系统后，我们要再安装命令补全这个软件：
yum -y install bash-completion
注意，再安装完之后还需要重新登陆一次shell终端才能生效哦！！
1、拷贝文件到系统opt文件夹下
2、解压
命令：tar -jxvf gcc-linaro-arm-linux-gnueabihf-4.7-2013.03-20130313_linux.tar.bz2
3、配置系统环境变量
命令：vim /etc/profile
命令：i
在末尾添加
export PATH=$PATH:/opt/gcc-linaro-arm-linux-gnueabihf-4.7-2013.03-20130313_linux/bin
命令：esc键》：》wq》回车
4、使命令生效
source /etc/profile 使环境变量生效
5、安装32位的库要和本地的64位版本一直
查看那个库含文件：yum provides libstdc++.so.6
然后把本机的版本升级
error：
Protected multilib versions: libstdc++-4.8.5-44.el7.i686 != libstdc++-4.8.5-39.el7.x86_64
yum update libstdc++-4.8.5-44.el7.x86_64 -y
yum update libstdc++-8.5.0-44.el7.x86_64 -y
安装：
yum install libstdc++-4.8.5-44.el7.i686
errot
Error: Failed to download metadata for repo 'appstream': Cannot prepare internal mirrorlist: No URLs in mirrorlist
centos8 Repository epel is listed more than once in the configuration - _海阔天空 - 博客园
centos镜像-centos下载地址-centos安装教程-阿里巴巴开源镜像站
CentOS，是基于 Red Hat Linux 提供的可自由使用源代码的企业级 Linux 发行版本；是一个稳定，可预测，可管理和可复制的免费企业级计算平台。
下载地址: 阿里云开源镜像站资源目录
阿里云开源镜像站资源目录
配置方法
1. 备份
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
2. 下载新的 CentOS-Base.repo 到 /etc/yum.repos.d/
CentOS 6
wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-6.repo
或者
curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-6.repo
CentOS 7
wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo
或者
curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo
centos8（centos8官方源已下线，建议切换centos-vault源）
wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-vault-8.5.2111.repo
或者
curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-vault-8.5.2111.repo
3. 运行 yum makecache 生成缓存
4. 其他
非阿里云ECS用户会出现 Couldn't resolve host 'mirrors.cloud.aliyuncs.com' 信息，不影响使用。用户也可自行修改相关配置: eg:
sed -i -e '/mirrors.cloud.aliyuncs.com/d' -e '/mirrors.aliyuncs.com/d' /etc/yum.repos.d/CentOError: Transaction check error: 安装的32位版本和本地64位版本不一致
file /usr/share/gcc-8/python/libstdcxx/v6/__pycache__/printers.cpython-36.opt-1.pyc from install of libstdc++-8.3.1-5.1.el8.i686 conflicts with file from package libstdc++-8.2.1-3.5.el8.x86_64
file /usr/share/gcc-8/python/libstdcxx/v6/__pycache__/printers.cpython-36.pyc from install of libstdc++-8.3.1-5.1.el8.i686 conflicts with file from package libstdc++-8.2.1-3.5.el8.x86_64
file /usr/share/gcc-8/python/libstdcxx/v6/__pycache__/xmethods.cpython-36.opt-1.pyc from install of libstdc++-8.3.1-5.1.el8.i686 conflicts with file from package libstdc++-8.2.1-3.5.el8.x86_64
file /usr/share/gcc-8/python/libstdcxx/v6/__pycache__/xmethods.cpython-36.pyc from install of libstdc++-8.3.1-5.1.el8.i686 conflicts with file from package libstdc++-8.2.1-3.5.el8.x86_64
file /usr/share/gcc-8/python/libstdcxx/v6/printers.py from install of libstdc++-8.3.1-5.1.el8.i686 conflicts with file from package libstdc++-8.2.1-3.5.el8.x86_64
file /usr/share/gcc-8/python/libstdcxx/v6/xmethods.py from install of libstdc++-8.3.1-5.1.el8.i686 conflicts with file from package libstdc++-8.2.1-3.5.el8.x86_64
error
-bash: /opt/gcc-linaro-arm-linux-gnueabihf-4.7-2013.03-20130313_linux/bin/arm-linux-gnueabihf-gcc: /lib/ld-linux.so.2: bad ELF interpreter: No such file or directory
命令：sudo yum install glibc.i686
6. /bin/arm-linux-gnueabihf-gcc: No such file or directory
得按装32位库
Centos8安装32位编译环境
Centos8安装32位编译环境
安装32位glibc库文件命令：(安装C库文件)
sudo yum install glibc-devel.i686
安装32位glibc++库文件命令
sudo yum install libstdc++-devel.i6865、查看命令生效情况
在终端上输入命令arm-linux-gnueabihf-gcc -v
看到下面内容说明成功了
Using built-in specs.
COLLECT_GCC=arm-linux-gnueabihf-gcc
COLLECT_LTO_WRAPPER=/opt/gcc-linaro-arm-linux-gnueabihf-4.7-2013.03-20130313_linux/bin/../libexec/gcc/arm-linux-gnueabihf/4.7.3/lto-wrapper
Target: arm-linux-gnueabihf
Configured with: /cbuild/slaves/oorts/crosstool-ng/builds/arm-linux-gnueabihf-linux/.build/src/gcc-linaro-4.7-2013.03/configure --build=i686-build_pc-linux-gnu --host=i686-build_pc-linux-gnu --target=arm-linux-gnueabihf --prefix=/cbuild/slaves/oorts/crosstool-ng/builds/arm-linux-gnueabihf-linux/install --with-sysroot=/cbuild/slaves/oorts/crosstool-ng/builds/arm-linux-gnueabihf-linux/install/arm-linux-gnueabihf/libc --enable-languages=c,c++,fortran --enable-multilib --with-arch=armv7-a --with-tune=cortex-a9 --with-fpu=vfpv3-d16 --with-float=hard --with-pkgversion='crosstool-NG linaro-1.13.1-4.7-2013.03-20130313 - Linaro GCC 2013.03' --with-bugurl=https://bugs.launchpad.net/gcc-linaro --enable-__cxa_atexit --enable-libmudflap --enable-libgomp --enable-libssp --with-gmp=/cbuild/slaves/oorts/crosstool-ng/builds/arm-linux-gnueabihf-linux/.build/arm-linux-gnueabihf/build/static --with-mpfr=/cbuild/slaves/oorts/crosstool-ng/builds/arm-linux-gnueabihf-linux/.build/arm-linux-gnueabihf/build/static --with-mpc=/cbuild/slaves/oorts/crosstool-ng/builds/arm-linux-gnueabihf-linux/.build/arm-linux-gnueabihf/build/static --with-ppl=/cbuild/slaves/oorts/crosstool-ng/builds/arm-linux-gnueabihf-linux/.build/arm-linux-gnueabihf/build/static --with-cloog=/cbuild/slaves/oorts/crosstool-ng/builds/arm-linux-gnueabihf-linux/.build/arm-linux-gnueabihf/build/static --with-libelf=/cbuild/slaves/oorts/crosstool-ng/builds/arm-linux-gnueabihf-linux/.build/arm-linux-gnueabihf/build/static --with-host-libstdcxx='-L/cbuild/slaves/oorts/crosstool-ng/builds/arm-linux-gnueabihf-linux/.build/arm-linux-gnueabihf/build/static/lib -lpwl' --enable-threads=posix --disable-libstdcxx-pch --enable-linker-build-id --enable-gold --with-local-prefix=/cbuild/slaves/oorts/crosstool-ng/builds/arm-linux-gnueabihf-linux/install/arm-linux-gnueabihf/libc --enable-c99 --enable-long-long --with-mode=thumb
Thread model: posix
6、安装编译共享32位库
在centos6.7 X64位机器上：
yum install xulrunner.i686
yum install libXtst.i686
错误：
在使用yum命令时
No match for argument:
Error: Unable to find a match
问题应该是没有配置 yum 源，所以解决办法就是：安装 EPEL 源
centos8:
yum install https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm