go run main.go
Then...
[root@m2np /]# ls
posts
followers
[root@m2np /]# login xxx xxx
login successful!
[root@m2np /]# cd posts
[root@m2np posts]# ls
output all posts of login user.
[root@m2np posts]# cd ../followers
[root@m2np followers]# ls
output all followers of login user.
[root@m2np followers]# exit
[root@m2np followers]# os
username: xxx
[root@m2np followers]# exit
Process finished with exit code 0