I have failed to install various programs on Ubuntu 20.04.3 LTS without knowing what's going on. Today I tried installing Zoom and got a clue about where the problem may be:
Malformed entry 53 in list file $ sudo apt update
E: Malformed entry 53 in list file /etc/apt/sources.list (URI parse)
E: The list of sources could not be read.
$ sudo -H gedit /etc/apt/sources.list"I went in that file with: sudo -H gedit /etc/apt/sources.list expecting to erase a bad line (53), but what I found was a long list of messages describing a problem with the original installation and all the Ubuntu Repository Sources being restricted as result:
MAIN LIST FILE CONTENTS
# deb cdrom:[Ubuntu 20.04.3 LTS _Focal Fossa_ - Release amd64 (20210819)]/ focal main restricted
# See for how to upgrade to
# newer versions of the distribution.
# deb-src focal main restricted
## Major bug fix updates produced after the final release of the
## distribution.
# deb-src focal-updates main restricted
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
# deb-src focal universe
# deb-src focal-updates universe...........................*** Longer links list that I cant post because stack exchange limit of 10 ***
1 Reset to default
