编辑：准确地放置所做的事情。
我需要在localhost没有密码的情况下通过SSH 连接，通常的做法（使用公钥）不起作用。
user@PC:~$ rm -rf .ssh/*
user@PC:~$ ssh-keygen -t rsa > /dev/null
Enter file in which to save the key (/home/user/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
user@PC:~$ ls .ssh/
id_rsa id_rsa.pub
user@PC:~$ ssh-copy-id -i localhost
The authenticity of host 'localhost (::1)' can't be established.
RSA key fingerprint is f7:87:b5:4e:31:a1:72:11:8e:5f:d2:61:bd:b3:40:1a.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'localhost' (RSA) to the list of known hosts.
user@localhost's password: …