shell脚本安装python、pip--这种写法是错误的---每一个命令执行完都要判断是否执行成功，否则无法进行下一步

shell脚本安装python、pip--不需要选择安装项目--不管用总报错，必须带上判断符号，while没有这种用法，写在这里为了以后少走弯路,
所以不要用下面的执行了

首先把pip-18.0.tar.gz 、Python-3.6..tgz 安装包放在 /usr/local 下面，按照顺序先安装pip，再安装python。不要先安装或只安装python，否则很容易出错，

#!/bin/bash
func1(){
    while true
    do
        echo "安装依赖包"
        yum -y install zlib-devel bzip2-devel openssl-devel ncurses-devel sqlite-devel readline-devel tk-devel gdbm-devel db4-devel libpcap-devel xz-devel
        echo "安装pip"
        yum remove pip -y && cd /usr/local/ && tar -xf pip-18.0.tar.gz && cd pip-18.0/ && python setup.py install
        echo "安装python"
        cd /usr/local/ && tar -zxvf Python-3.6..tgz && mv Python-3.6. python3 && cd python3 && ./configure && make && make install
        mv /usr/bin/python /usr/bin/python.bak
        ln -s /usr/local/bin/python3 /usr/bin/python && ln -s /usr/local/python3/bin/pip3 /usr/bin/pip3
        whereis pip && /usr/local/bin/pip3. install --upgrade pip && /usr/local/bin/pip install paramiko
        sed -i "1c #!/usr/bin/python2.7" /usr/bin/yum
        sed -i "1c #!/usr/bin/python2.7" /usr/libexec/urlgrabber-ext-down
        sed -i "1c #!/usr/bin/python2.7" /usr/sbin/firewalld

        echo "全部安装完毕"
        exit
    done
}
func1