issue in installing gazenbo on ubuntu 20.0.4 using terminal

Question

line:wget https://packages.osrfoundation.org/gazebo.key -o- | sudo apt-key add -

gpg: no valid OpenPGP data found.

Answer 1

Your syntax is wrong. -o- should be -O -.

wget https://packages.osrfoundation.org/gazebo.key -O - | sudo apt-key add -

-o writes the log output to a file, not the downloaded content. And by setting -o - you basically redirect the log output back to stdout.