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Accepted
Josef Klimuk
Asked: 2022-06-30 05:32:58 +0800 CST

How to use special characters as user input

  • 772

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.

command-line

2 Answers

  1. Best Answer

    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)

    • 3

  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
    • 2