Check out https://www.mono-project.com/download/stable/ and follow the instructions to add their repositories for Ubuntu 18.04. After running the
apt update step, you will have those versions of mono available to install via
You can also browse their repository manually if it's easier for you to find what you want. Just direct your browser to https://download.mono-project.com/repo/ubuntu/. If you're not familiar with how
apt repos work, you can look under https://download.mono-project.com/repo/ubuntu/dists for index files. These are text files that list what packages they have made available for a particular distribution/version. Each block of text is like the output from
apt show, for example,
Maintainer: Debian Mono Group <[email protected]>
Depends: libmono-corlib4.5-cil (>= 4.0.0~alpha1)
Description: Visual Basic 2012 Cecil libraries for Mono
This package contains the Cecil libraries for the Mono Visual Basic library,
aimed at the specifications / features of the Visual Basic 2012.
Mono is a platform for running and developing applications based on the
ECMA/ISO Standards. Mono is an open source effort led by Novell.
Mono provides a complete CLR (Common Language Runtime) including compiler and
runtime, which can produce and execute CIL (Common Intermediate Language)
bytecode (aka assemblies), and a class library.
filename line tells you where to find the actual
.deb file relative to the server root. Here, it would be https://download.mono-project.com/repo/ubuntu/pool/main/m/mono-basic/libmono-cecil-vb0.9-cil_4.7-0xamarin3+ubuntu1804b1_all.deb. That said, once you've found the thing you want in the package file, you can also just
apt-get install mono-basic, and the package manager will take care of the rest.