Loop to write ascii-text to serial port

send.sh

#!/bin/sh

if [[ $# == 0 ]]; then
    echo "Usage: send.sh <serial port>" >&2
    exit 1
fi

echo "Writing to $1; Press Ctrl+C to exit"
echo

while :
do
    read -p "> " message
    echo -n "$message" > "$1"
done