Hi @wowwhy, the Debian packages install Bitsquare under the so-called “application software packages” directory, exactly under /opt/Bitsquare, which is not in the user’s $PATH environment variable, thus you must either add that directory to your $PATH or provide the full path to the Bitsquare binary when running it, i.e. /opt/Bitsquare/Bitsquare instead of bitsquare.
Or you may use the provided desktop menu entry and forget about command line issues.