$ lsof -i tcp:8081
$ kill PID
$ ps aux
$ ps aux | grep "process name"
$ pkill processID
$ chsh -s /bin/zsh
$ chsh -s /bin/bash
$ chsh -s $(which zsh)
$ tmux split-window
$ tmux split-window -h
$ echo $ANDROID_HOME
Htop Activity Monitor
$ htop
User manual
$ man programName
$ netstat -tulpn | grep 80
$ ls -a
$ ls -al
$ ls -lrt
$ touch fileName.fileExtension
$ which programName
$ printenv
$ grep -rnw ./ -e "word"
$ nslookup example.com
$ dig ns example.com