Useful Linux command line tools

This is an incomplete list of some useful Linux/*BSD command-line tools:

Command Description
ncdu List size of directories and files
sed -i 's/old/new/' Find & replace with Regex
telnet host port Test cleartext network connection
openssl s_client -connect host:port Test encrypted network connection
vim/emacs (Most) Powerful text editor. Install COC plugins for the awesome vscode language server.
fd Awesome rust replacement for find
rg Awesome rust replacement for grep
bat Not a replacment for cat but an addition
netstat -tulpn Show open network ports