One Wire, Many Conversations

Type tmux, and all that appears is a green bar at the bottom. Nothing looks multiplexed yet.

The mux in the name is short for multiplexer; multiplex is a telegraph word for sharing one wire between several conversations. In 1874 Edison built a device that carried four signals at once over one wire, and sold the rights the following January for $30,000. That same year, 1874, the French engineer Émile Baudot patented a scheme that sliced time into intervals to fit four conversations on one line, later raised to five. His name lives on in the baud.

The scarce thing now is not wire but your screen and keyboard. Several shells ride on them, which is why this is a terminal multiplexer.

How do you share the one line you have? A question from a century and a half ago, still named on the tool in front of you.