如何使用shell脚本通过expect实现自动单边无密登录功能？

EXPECT=/usr/bin/expect 

$EXPECT <<EOF 
spawn ssh-keygen -t rsa 
expect "*ssh/id_rsa*" { 
 send -- "\r" 
 expect "*for no passphrase*" 
 send -- "\r" 
 expect "*passphrase again*" 
 send -- "\r" 
 exp_continue 
} 
EOF 
iplist=`cat /root/ip.list` 
for ip in $iplist 
do 
 $EXPECT <<EOF 
 spawn ssh-copy-id root@$ip 
 expect "*(yes/no)?*" { 
  send -- "yes\r" 
  expect "*?assword:*" 
  send -- "$PASSWD\r" 
 } "*?assword:*" { 
  send -- "$PASSWD\r" 
  exp_continue 
 } 
EOF 
done