Cannot compare received user input via read

Question

I have the following shell script:

#!/bin/bash

if [ "`read -n 1`" == "c" ] ; then
    printf "\nfoo\n"
    exit 0
fi

printf "\nbar\n"
exit 0

However, regardless of the input, I always get bar as the output:

$ ./test.sh
c
bar
$ ./test.sh
d
bar

Why is this occuring and what do I need to change in the shell script?

Answer 1

You need to read it into a variable first, otherwise you're just comparing the output value of read (which is empty value).

Following should work:

#!/bin/bash

read -n 1 ch
if [ "$ch" == "c" ] ; then
    printf "\nfoo\n"
    exit 0
fi

printf "\nbar\n"
exit 0