121. Installing Mono for Ubuntu 18.04 (i386, amd64, armhf, arm64, ppc64el)
http://www.mono-project.com/download/stable/
$ sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
$ echo "deb https://download.mono-project.com/repo/ubuntu stable-bionic main" | sudo tee /etc/apt/sources.list.d/mono-official-stable.list
$sudo apt update
122. Installing Sound works
http://rtlsdr.org/softwarelinux
$ sudo apt-get install libportaudio2
123. Build SDR#
http://github.com/cgommel/sdrsharp
$ git clone http://github.com/cgommel/sdrsharp
$ cd sdrsharp
$ xbuild /p:TargetFrameworkVersion="v4.5" /p:Configuration=Release
124. Softlinks for Mono executable find Audio libraries
http://www.scivision.co/sdr-sharp-ubuntu/
$ cd Release
$ ln -s /usr/lib/x86_64-linux-gnu/libportaudio.so.2 libportaudio.so
$ ln -s /usr/lib/x86_64-linux-gnu/librtlsdr.so.0 librtlsdr.dll
125. Add one line in \Home\sdrsharp\Release\SDRSharp.exe.config
<add key="RTL-SDR (USB)" value="SDRSharp.RTLSDR.RtlSdrIO,SDRSharp.RTLSDR" />
126. Compile it so that it may run a bit faster
$ mono --aot --optimize=all --optimize=float32 SDRSharp.exe
127. Run SDR# using Mono
$ mono SDRSharp.exe