Things you didn't know about GNU readline (2019)(twobithistory.org)

    #!/bin/sh
    # Simple chat system frontend, wrapping gyap in rlwrap and maybe ssh.
    : ${GYAP_LOGFILE=$HOME/gyap.log} ${GYAP_COMMAND=gyap}
    if [ "$#" -eq 0 ]; then
        rlwrap -C gyap -l "$GYAP_LOGFILE"             "$GYAP_COMMAND" "$@"
    else
        host=$1; shift
        rlwrap -C gyap -l "$GYAP_LOGFILE" ssh "$host" "$GYAP_COMMAND" "$@"
    fi

    #!/bin/sh
    : Simple chat system.  cf. rgyap.  ${nick=${1-$USER}} ${chan=${2-/var/tmp/chat}}
    echo "Chatting on $chan as <$nick> (override with $0 \$nick [\$chan])"
    touch "$chan" && chmod 666 "$chan" 2>/dev/null
    sign() {
        echo "$(date +%T) * $nick signed $1 ($(date +%05Y-%m-%d))" >> "$chan"
    }
    echo "Press ^R if a chat line appears as you are typing.  Recently:"
    tail -Fn 16 "$chan" & pid=$?; trap "sign off; sleep .1; kill $pid" 0
    sign on; while read t; do echo "$(date +%T) <$nick> $t"; done >> "$chan"

    set show-mode-in-prompt on
    set emacs-mode-string \1\e[1 q\2
    set vi-cmd-mode-string \1\e[3 q\2
    set vi-ins-mode-string \1\e[5 q\2

    mkdir -p foo/bar
    cd !$          # => cd foo/bar

    let mut line = String::new();
    std::io::stdin().read_line(&mut line).unwrap();

    let line = rt.spawn_blocking(|| {
        use std::io::stdin;

        let mut buffer = String::new();
        stdin().read_line(&mut buffer).unwrap()
    }).await.unwrap();