This is another GNU Radio and RTL2832U Software Defined Radio tutorial based on the article I did on Ubuntu 18.04. ElementaryOS is one of Ubuntu based operating system. The ElementaryOS is designed to be easy to use and the user interface is a lot like the macOS. This ElementaryOS GNU Radio installation tutorial is made for people who just started using Linux so they can transition painlessly to using Linux for RTL SDR and GNU Radio purposes.
Installing the GNU Radio and GNU Radio Companion
Installing GNU Radio and the GNU Radio companion is as easy on ElementaryOS as it is on Ubuntu 18.04, all we need is to access the gnuradio package from APT.
# apt install gnuradio
The package installation takes a while, after finishing the GNU Radio 3.7.11-10 is finally installed on the computer. You can access the GNU Radio Companion program via Terminal or via Application Launcher.
$ gnuradio-companion
Now, we can use GNU Radio and the GNU Radio Companion, the next step of this tutorial is to install the RTL SDR package to use with GNU Radio. This will allow us to receive the IQ data from RTL SDR and use the GNU Radio to process the data as we need.

GNU Radio Source
As we can see on the Terminal output of gnuradio installation, the rtl-sdr driver is already installed, the only thing needed to be installed is the GNU Radio Blocks for RTL-SDR via the gr-osmosdr package. The gr-osmosdr is already available in the APT in ElementaryOS.
# apt install gr-osmosdr
After installing the GNU OsmoSDR module, we can access the RTL-SDR source block on GNU Radio Companion under the Sources category.

This concludes the tutorial on how to install GNU Radio Companion on ElementaryOS. Other Ubuntu based operating system should work the same, the APT can be used as a simple way to install the GNU Radio. However, it may not be the latest version, if you need the latest version always use the source and compile your own version by CMake.