How to assign variable to output of the program in bash?

Question

Here I have the simple code in which I am trying to store the value of program output to a variable in bash.

#!/bin/bash
i=0
for value in {1..10}
do 
    variable=`$value | ./unpackme`
    str="What's my favorite number? Sorry, that's not it!"
    if [[ "$variable" == "$str" ]]
    then
        echo "hello"
    fi
done

The output I am getting is as follows: Output screenshot Please help me fix this. Thanks in advance.

What does `./unpackme` do? Why are you piping the output of `$value` to it? — choroba, Mar 17 '22 at 11:50
`$value` will try to run a program called `1`. Do you mean `echo $value` ? — Joe, Mar 17 '22 at 11:54

Bruno · Answer 1 · 2022-03-18T11:00:00.677

You may try :

#!/bin/bash

str="What's my favorite number? Sorry, that's not it!"
for value in {1..10}; do
    variable=$(./unpackme <<< "$value")
    if [ "$variable" = "$str" ]; then
        echo "hello"
    fi
done

Some notes :

New style $(command) is preferred to `command`.
string in command <<< string is what is called a here string : command standard input is fed with string (think of it as : echo string | command).
[ "$variable" = "$str" ]: Take care of [[ "$a" == "$b" ]]/[[ "$a" = "$b" ]], they will consider the right part of ==/= as a pattern, and may not do what you want.

How to assign variable to output of the program in bash?

1 Answers1