One of the following scenarios apply:
Problem scenario #1
You are trying to view namespaces on a Linux server. You run "lsns" but you get "lsns: command not found."
Problem scenario #2
You run this:
sudo apt -y install util-linux
You see "util-linux is already the newest version (2.27.1-6ubuntu3.8)"
What should you do on a Debian derivative of Linux (e.g., Kali Linux, Ubuntu, Linux Mint, etc.)?
Possible Solution #1
If you are using Ubuntu Linux 16.x or lower, it may be too old to be supported. util-linux 2.28 is needed. Based on these two links (https://packages.ubuntu.com/xenial/util-linux for Ubuntu 16.x and https://packages.ubuntu.com/bionic/util-linux for Ubuntu 18.x), we think that you need a version of Ubuntu Linux higher than 16.x.
Possible Solution #2
sudo apt -y update sudo apt -y install util-linux
If it still does not work, get the package you need from here: https://pkgs.org/download/util-linux
sudo dpkg --print-architecture