While loop with function that asks for user input

Question

I got this function:

#!/bin/bash
prompt() {
read -r -p "${1:-Usunąć podany plik? [t/N]} " response
case "$response" in
    [tT][eE][sS]|[tT])
        true
        echo "Usuwam... $line"
        ;;
        *)
        false
        echo "Pomijam... $line"
        ;;
esac
}

And I want it to work inside a loop that reads line by line from a .txt file:

while IFS= read -r line
        do
            echo "$line" && prompt
        done < lista.txt

As I run the script here's the output (it doesn't actually prompt for user input):

11M /home/kamil/TEST/FOLDER ZE SPACJAMI/PLIK ZE SPACJAMI2.pdf
Pomijam... 11M /home/kamil/TEST/FOLDER ZE SPACJAMI/PLIK ZE SPACJAMI2.pdf
11M /home/kamil/TEST/FOLDER ZE SPACJAMI/PLIK ZE SPACJAMI4.pdf
Pomijam... 11M /home/kamil/TEST/FOLDER ZE SPACJAMI/PLIK ZE SPACJAMI4.pdf
11M /home/kamil/TEST/FOLDER ZE SPACJAMI/PLIK ZE SPACJAMI6.pdf
Pomijam... 11M /home/kamil/TEST/FOLDER ZE SPACJAMI/PLIK ZE SPACJAMI6.pdf

The lista.txt file looks like that if I use this loop:

while IFS= read -r line
        do
            echo "$line"
        done < lista.txt

Output:

11M /home/kamil/TEST/FOLDER ZE SPACJAMI/PLIK ZE SPACJAMI2.pdf
11M /home/kamil/TEST/FOLDER ZE SPACJAMI/PLIK ZE SPACJAMI3.pdf
11M /home/kamil/TEST/FOLDER ZE SPACJAMI/PLIK ZE SPACJAMI4.pdf
11M /home/kamil/TEST/FOLDER ZE SPACJAMI/PLIK ZE SPACJAMI5.pdf
11M /home/kamil/TEST/FOLDER ZE SPACJAMI/PLIK ZE SPACJAMI6.pdf
11M /home/kamil/TEST/FOLDER ZE SPACJAMI/PLIK ZE SPACJAMI.pdf

My desire is that it prompts a user input as it reads every line.

Use a different FD at the outer read which is being done by the while loop. — Jetchisel
– Jetchisel, Commented Mar 24, 2021 at 19:30
Thanks @Jetchisel it works to I'm learning bash at that -ru9 is new to me. — kamil_debski
– kamil_debski, Commented Mar 24, 2021 at 20:04

Philippe · Accepted Answer · 2021-03-24 19:42:02Z

1

The line you need to change is :

read -r -p "${1:-Usunąć podany plik? [t/N]} " response < /dev/tty

answered Mar 24, 2021 at 19:42

Philippe

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2 Comments

kamil_debski Over a year ago

Thanks @Philippe that does the trick for me! Now I wonder what's the diffrence because when I'm trigering function alone it asks for input without that addon.

Philippe Over a year ago

When you trigger function alone, read get inputs from standard input which is the same as /dev/tty. But when you put prompt inside while loop, prompt.read is also reading from the file. That's why you need to tell it to read from terminal, which is /dev/tty.

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