yum install git 安装的版本比较底，下载代码时有可能报错： 

error: while accessing http://github.com/...
fatal: HTTP request failed
需要卸载旧版本,下载最新安装版本 


#卸载
yum remove git
#安装依赖
yum install curl-devel expat-devel gettext-devel openssl-devel zlib-devel asciidoc
yum install  gcc

#从这里查看最新版本http://mirrors.edge.kernel.org/pub/software/scm/git/
cd /usr/local/src/

wget http://mirrors.edge.kernel.org/pub/software/ scm/git/git-2.24.1.tar.gz

tar -zvxf git-2.24.1.tar.gz

cd git-2.24.1

make prefix=/usr/local/git all

make prefix=/usr/local/git install

echo "export PATH=$PATH:/usr/local/git/bin" >> /etc/profile

source /etc/profile


配置SSH 
ssh-keygen -t rsa -C "邮箱"

确认路径按1次回车，提示：Enter passphrase（输入密码），不用输密码再按2次回车即可。生成的密钥存放目录 /root/.ssh/
id_rsa：私钥 ，id_rsa.pub：公钥
在github上添加ssh key(http://github.com/settings/keys),把id_rsa.pub的内容复制过去