How to use special characters as user input

Question

I want to use user input of special characters in conditional statement. I tried:

read -p "press arrow up" foo
if [ $foo == "^[[A" ]; then echo yes; fi

It did not do what I wanted it to do.

Answer 1

In bash, you could use ANSI-C quoting

#!/bin/bash

read -p "press arrow up " foo

if [ "$foo" = $'\e[A' ]; then
  echo 'yes'
fi

For a more nuanced version, see BASH question: using read, can I capture a single char OR arrow key (on keyup)

Answer 2

Not especially beautiful, but you could compare hex values.

To find out hex value of up arrow, assign foo manually and run

xxd <<< "$foo"

Copy paste the output to your script and use xxd -r to revert the hex value:

up_arrow="$(xxd -r <<< "00000000: 1b5b 410a")"
if [ "$foo" = "$up_arrow" ]; then echo yes; fi