通过sed -i ，通过准备好的sh脚本，来设置linux iptable白名单

sed -i ‘/特定字符串/i 新行字符串‘ file

#!/bin/bash
del_stdin_buf()
{
    read -d ‘‘ -t 0.1
}
echo "Setting https enabled for remote access...."

https_port=`grep ‘dport 443‘ /etc/sysconfig/iptables | wc -l`
if [ $https_port -eq 0 ]
then 
     sed -i "/-A INPUT -j REJECT --reject-with icmp-host-prohibited/i -A INPUT -m state --state NEW -m tcp -p tcp --dport 443 -j ACCEPT" /etc/sysconfig/iptables
fi
http_port=`grep ‘dport 80‘ /etc/sysconfig/iptables | wc -l`
if [ $http_port -eq 0 ]
then 
     sed -i "/-A INPUT -j REJECT --reject-with icmp-host-prohibited/i -A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT" /etc/sysconfig/iptables
fi

service iptables restart
echo "Done."