使用shell脚本实现自动SSH互信功能

 说假设有一个1000台节点的Hadoop集群，要配置节点之间的SSH免密码登录，该如何用shell脚本实现？

#!/bin/expect

#循环1000台机器的IP地址，生成密钥文件authorized_keys

for ip in {cat ip.list}
do
    ssh user@$ip ssh-keygen -t rsa  &>/dev/null
    expect{
                "yes/no" { send "yes\r";exp_continue}
                "password:"{send "$passwd\r";exp_continue}
              }
    cat ~/.ssh/id_rsa.pub > ~/.ssh/authorized_keys &> /dev/null  
    exit
    if [ !-f ~/.ssh/authorized_keys ];
    then
       touch ~/.ssh/authorized_keys
    fi
    ssh user@$ip cat ~/.ssh/authorized_keys >> ~/.ssh/authorized_keys  &> /dev/null
    expect{
                "yes/no" { send "yes\r";exp_continue}
                "password:"{send "$passwd\r";exp_continue}
              }   
done

#scp authorized_keys 文件到各台机器上面。
for ip in {cat ip.list}
do
   scp ~/.ssh/authorized_keys user@$ip:~/.ssh/ 
    expect{
                "yes/no" { send "yes\r";exp_continue}
                "password:"{send "$passwd\r";exp_continue}
              }  
done