standard in must be a tty

今天执行一个脚本，报如下错误：
[yx@test]$ ./case.sh ssh_date_auth
standard in must be a tty
standard in must be a tty
standard in must be a tty
standard in must be a tty
standard in must be a tty
standard in must be a tty
standard in must be a tty

原因是脚本里面有
su - yx <     com1;
    com2;
    .....
eof

所以会出现那个问题，换成root用户执行,或者配置yx用户有sudo权限用sudo  ./case.sh ssh_date_auth 也可以解决