Later update: I stopped using Mutate and switched to Ulauncher. You can find out more here: Ulauncher is my new favorite app launcher for Linux.
I'm using a Macbook when I'm in the office, but at home I'm a happy Linux user. My distro of choice is Linux Mint Debian 2 (LMDE2).
While the lack of keyboard shortcuts on OS X bothers me from time to time, when I'm on Linux I miss Alfred a lot. Today I spent some time looking for alternatives. I remembered that a few years ago I saw a friend using something similar for Ubuntu, so there must be something for my distro as well.
That's how I discovered Mutate. LMDE doesn't support PPAs, so I tried the .deb package and it worked. The only thing I had to configure was the shortcut. By default it uses Ctrl + D for general search and Ctrl + T for Google Translate. I found the second one quite annoying (that's the shorcut to open tabs) and the first one only after I opened preferences. To change them, open Mutate (any of the shortcuts above) and type "Preferences". I removed both shortcuts and added Ctrl + Space for default search.
Update: If you also added the program to startup list, you might find it annoying that the mutate UI opens after you login. Apparently this can be solved by calling the following command:
Found on GitHub issue 64.