Command-line interface conventions

• https://nullprogram.com/blog/2020/08/01/
• http://www.catb.org/~esr/writings/taoup/html/ch10s05.html
• https://tldp.org/LDP/abs/html/standard-options.html
• https://www.gnu.org/prep/standards/html_node/Command_002dLine-Interfaces.html
• https://stackoverflow.com/questions/8957222/are-there-standards-for-linux-command-line-switches-and-arguments