Find and remove obsolete PPA repositories

It happens sometimes , when running the update command

 sudo apt-get update

That we face some errors like :




This clearly indicates obsolete PPA repositories,To delete them, just run the following command :

1. List the obsolete PPA repositories  :

 sudo apt-get update | grep "Failed"

 E: The repository 'http://ppa.launchpad.net/colingille/freshlight/ubuntu bionic Release'    
 E: The repository 'http://ppa.launchpad.net/nilarimogard/webupd8/ubuntu bionic  Release'    

2. Find the files containing ths obsolete PPA repository in the sources.list.d :

 - 2.1 PPA repo : http://ppa.launchpad.net/colingille/freshlight/ubuntu

 grep -rnw '/etc/apt/sources.list.d' \

  -e 'http://ppa.launchpad.net/colingille/freshlight/ubuntu bionic'

/etc/apt/sources.list.d/colingille-ubuntu-freshlight-bionic.list:1:deb http://ppa.launchpad.net/colingille/freshlight/ubuntu bionic main
/etc/apt/sources.list.d/colingille-ubuntu-freshlight-bionic.list:2:# deb-src http://ppa.launchpad.net/colingille/freshlight/ubuntu bionic main
/etc/apt/sources.list.d/colingille-ubuntu-freshlight-bionic.list.save:1:deb http://ppa.launchpad.net/colingille/freshlight/ubuntu bionic main
/etc/apt/sources.list.d/colingille-ubuntu-freshlight-bionic.list.save:2:# deb-src http://ppa.launchpad.net/colingille/freshlight/ubuntu bionic main

Comment or delete the PPA repository in the different listed files.

 - 2.1 PPA repo : http://ppa.launchpad.net/nilarigomard/webupd8/ubuntu

 grep -rnw '/etc/apt/sources.list.d' \

   -e 'http://ppa.launchpad.net/nilarigomard/webupd8/ubuntu bionic'

/etc/apt/sources.list.d/nilarimogard-ubuntu-webupd8-bionic.list:1:deb http://ppa.launchpad.net/nilarimogard/webupd8/ubuntu bionic main 

/etc/apt/sources.list.d/nilarimogard-ubuntu-webupd8-bionic.list:2:# deb-src http://ppa.launchpad.net/nilarimogard/webupd8/ubuntu bionic main

Comment or delete the PPA repository in the different listed files.

That's it :-)