Level 18 -> 19

$ man ssh

-t      Force pseudo-terminal allocation.  This can be used to execute arbitrary screen-based programs on a
        remote machine, which can be very useful, e.g. when implementing menu services.  Multiple -t options
        force tty allocation, even if ssh has no local tty.

$ ssh bandit18@bandit.labs.overthewire.org -p 2220 -t "ls -la"

This is a OverTheWire game server. More information on http://www.overthewire.org/wargames

bandit18@bandit.labs.overthewire.org's password: 
total 24
drwxr-xr-x  2 root     root     4096 May  7  2020 .
drwxr-xr-x 41 root     root     4096 May  7  2020 ..
-rw-r--r--  1 root     root      220 May 15  2017 .bash_logout
-rw-r-----  1 bandit19 bandit18 3549 May  7  2020 .bashrc
-rw-r--r--  1 root     root      675 May 15  2017 .profile
-rw-r-----  1 bandit19 bandit18   33 May  7  2020 readme
Connection to bandit.labs.overthewire.org closed.

$ ssh bandit18@bandit.labs.overthewire.org -p 2220 -t "cat ~/readme"

This is a OverTheWire game server. More information on http://www.overthewire.org/wargames

bandit18@bandit.labs.overthewire.org's password:
IuekXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Connection to bandit.labs.overthewire.org closed.

Password = IuekXXXXXXXXXXXXXXXXXXXXXXXXXXXX

bandit