Install btop++ (A advance CLI system monitor):
===============================================
sudo apt install btop

Sources:
https://www.omgubuntu.co.uk/2021/11/best-command-line-tools-ubuntu-linux
https://launchpad.net/~bashtop-monitor/+archive/ubuntu/bashtop

Date: November 18th 2021

Update: April 23rd, 2022
Binary from snap is no longer available for arm, must build through this setup on non x86 setups:

sudo apt install coreutils sed git build-essential gcc g++
*Needs to be at least GCC-11 or newer!
git clone https://github.com/aristocratos/btop.git
cd btop
make -j$(nproc)
sudo make install

Source: https://github.com/aristocratos/btop


Update: June 3rd 2022
You can create a PowerPC binary (big edian) by:
on my laptop
git clone https://github.com/aristocratos/btop.git
cd btop
make CXX=powerpc-linux-gnu-g++-11
or
make CXX=powerpc64-linux-gnu-g++-11

then copy it to the powerpc device and run this
sudo make install

source: https://issuekiller.com/issues/aristocratos/btop/80741510

Update (April 4th 2024): Changed snap to apt install for btop++ available in Ubuntu 23.10.