问创建ftp用户无法切换该用户，如何解决？

ubuntu@VM-0-5-ubuntu:/home$ sudo useradd -m -d /home/songyu -s /sbin/nologin songyu

ubuntu@VM-0-5-ubuntu:/home$ sudo passwd songyu

Enter new UNIX password:

Retype new UNIX password:

passwd: password updated successfully

ubuntu@VM-0-5-ubuntu:/home$ su songyu

Password:

Cannot execute /sbin/nologin: No such file or directory