I'm accessing a linux system [Ubuntu16.04 LTS] remotely. A lot of things seem to be messed up. I need to install libgmp-dev, which gives E: Sub-process /usr/bin/dpkg returned an error code (1) error. After trying a few things, I thought apt-get update might help, but sudo apt-get update gives error:
Err:18 http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial/main amd64 Packages
404 Not Found
W: The repository 'http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Failed to fetch http://ppa.launchpad.net/mc3man/trusty-media/ubuntu/dists/xenial/main/binary-amd64/Packages 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.
Read a few posts and it seems removing the ppa is the solution, however I'm not sure how to do that from the command line. This popular answer suggests sudo apt-get install ppa-purge before removing the ppa. But running sudo apt-get install ppa-purge again gives error E: Sub-process /usr/bin/dpkg returned an error code (1).
I want to try the solution sudo add-apt-repository --remove ppa:whatever/ppa but embarrassing enough I'm not sure what to put in place of whatever because I never installed these ppas (I only just got access to this system).
Output of ls /etc/apt/sources.list.d is:
aheck-ubuntu-ppa-xenial.list mc3man-ubuntu-xerus-media-xenial.list nccl-2.1.15-ga-cuda8.0.list.save
aheck-ubuntu-ppa-xenial.list.save multiverse.list opennms.list
blahota-ubuntu-texstudio-xenial.list multiverse.list.save sublime-text.list
blahota-ubuntu-texstudio-xenial.list.save myppa.list sublime-text.list.save
mc3man-ubuntu-trusty-media-xenial.list myppa.list.save
mc3man-ubuntu-trusty-media-xenial.list.save nccl-2.1.15-ga-cuda8.0.list
EDIT:
When I run apt-get update a lot of ppas from mc3man don't give any error, except the one (amd64), is it safe to remove all of these files which come as output of grep mc3man * inside /etc/apt/sources.list.d/?
mc3man-ubuntu-trusty-media-xenial.list:deb http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial main
mc3man-ubuntu-trusty-media-xenial.list:# deb-src http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial main
mc3man-ubuntu-trusty-media-xenial.list.save:deb http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial main
mc3man-ubuntu-trusty-media-xenial.list.save:# deb-src http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial main
mc3man-ubuntu-xerus-media-xenial.list:deb http://ppa.launchpad.net/mc3man/xerus-media/ubuntu xenial main
mc3man-ubuntu-xerus-media-xenial.list:# deb-src http://ppa.launchpad.net/mc3man/xerus-media/ubuntu xenial main
EDIT2:
mv mc3man-ubuntu-trusty-media-xenial.list mc3man-ubuntu-trusty-media-xenial.list.bak worked because I'm behind a proxy, now the error is:
E: Could not get lock /var/lib/apt/lists/lock - open (11: Resource temporarily unavailable)
E: Unable to lock directory /var/lib/apt/lists/