www.makemkv.com

Hello,
i installed makemkv on Debian 7, if i type makemkv in the command line, I get this error:
makemkv: cannot connect to X server
Where is the problem?

Do you have X running? If not, there is no X server to connect to, so the graphic interface can't run.

The console version has a different file name.

also are you trying to run it as root if so try using sux instead of su or sudo. Some distros only allow you to launch X applications as root using sux in terminal when logged in as another user.