Termux is a terminal emulator for Android that provides a Linux environment that works directly with or without rooting and with no setup required. The installation of additional packages is a trivial task thanks to its own APT package manager (which makes a difference in comparison to other terminal emulator apps). You can search for specific packages by using the command
pkg search <pkg_name> and install packages with
pkg install <pkg_name>. You can install Termux straight from Google Play.