While reading about trying to get Rust to run in a REPL, I learned that you can send messages between terminals by redirecting to /dev/pts/{num}.

For example:

echo "hello from 1" 1>/dev/pts/2

Will print “hello from 1” to your second open terminal.

You can use this to redirect stderr to a different open terminal if, for example, you have a lot of stdout messages being printed in your original terminal window, or if you are running a TUI application.