Wait for UART device, read it, and dump the received data to a text file and to the screen

grab_uart.sh

#!/bin/bash

set -eu

DEVICE="$1"  # e.g.: /dev/ttyUSB0
BAUD_RATE="$2"  # e.g.: 115200
OUTPUT_FILE="$3"  # e.g.: uart.txt

echo "Waiting for $DEVICE to become available ..."
while true
do
  if [ -e "$DEVICE" ]
  then
    echo "Waiting for write permissions ..."
    while [ ! -w "$DEVICE" ]
    do
      true
    done

    echo "Setting baud rate ..."
    stty -F "$DEVICE" "$BAUD_RATE"

    echo "Reading from $DEVICE to $OUTPUT_FILE"
    tee "$OUTPUT_FILE" < "$DEVICE"
    break
  fi
done