cant install in ubuntu 18.04
I suppose, the culprit is your redis-server package. First check, if there is a currently running redis-server:
sudo service --status-all
...
[ + ] redis-server
....
If there is one, stop it manually:
sudo service redis-server stop
Then de-install and re-install the redis-server:
sudo apt-get purge redis-server
sudo apt-get update
sudo apt install redis-server
Check for any errors, i.e. redis trying to bind to an IPv6 interface where no IPv6 is active and such stuff. A look into the logfiles will help you to find the cause of the problems. If the installation of redis-server is successful, You can retry to install BigBlueButton in the usual way.
It might be an idea to change the installation scriptlets of the depending packages to check for a working redis-server, but I have no clue yet, how to accomplish this. Ideas are welcome.
Use this: https://github.com/bigbluebutton/bbb-install/issues/410 maybe help you