Login command fails and closes connection

Question

I’m trying to execute the login command but it fails.

As root (via SSH) I get:

root@server:~# login
Connection to 192.168.0.50 closed.

The SSH connection is closed. In a “physical” TTY the session is closed and I go back to the login screen.

As a regular user using sudo:

bilbax@server:~$ sudo login
Password: 

[1]+  Stopped                 sudo login

Just before this bug appeared, I tried to use the login command as usual, it worked, it asked for the password. I typed it wrong, I retried, but the command froze. I tried ^C, without success. So, as root, I executed killall login; didn't worked too. I rebooted the system and now I have to bug described above.

Did I do something wrong by killing the command?

I’m on Arch Linux x86_64 (kernel 3.4.7-1-ARCH).

Answer 1

The problem with su will be that it doesn't chown the tty to the new user. That doesn't matter when you're su'ing to root, but for other users not owning the tty leads to difficulty.

Running login from the shell used to be a normal (or at least acceptable) thing to do. Shells treated it specially, implicitly doing an exec. Modern shells don't seem to do that any more. Running exec login explicitly might help. Adding -f username is another thing to try.

When you do it as a non-root user, it only works if login is setuid-root, which used to be the standard setup but isn't so common anymore. The sudo version might also work if preceded by exec, assuming sudo is smart enough to get out of the way (i.e. do a direct exec itself, not a fork+exec+wait)

After going through all that I wonder why you don't just ssh host -l minecraft and cut out the middleman