Bandit8
Website URL: http://overthewire.org/wargames/bandit/bandit8.html
Log in to the game server using credentials of bandit7 (see this for walkthrough for that level).

OverTheWire webpage for bandit8 says:
The password for the next level is stored in the file data.txt next to the word millionth
Let’s use ls -l in the home directory.
ls -l

The first thing you should note about the file is it’s size. The file is 4184396 bytes long, which is huge! So, it’s better if we don’t use cat command on the file.
The next logical option that should come to your mind is grep. According to what we know, the password should be near the word “millionth”. Let’s grep that.
grep "millionth" data.txt
And lo behold! We got it!