These are a list of usages of shell commands I can't live without on UNIX-based systems.
Using Homebrew
brew install pstree # to be able to use pstree
brew install vnstat # to be able to use vnstat
brew install ncdu # to use ncdu
brew install ipcalc # to use the almighty ipcalc
brew install htop # to use htop
brew install ack # to use the awesome ack
brew install lsof # to use the amazing lsof
Using APT you can install the tools with the following RPM packages:
apt-get install psmisc # to be able to use pstree
apt-get install vnstat
apt-get install ncdu
apt-get install ipcalc
apt-get install htop
apt-get install ack
apt-get install lsof