CODEWITHSUNDEEP
linuxbashshell
DrunkCoder
DrunkCoder

Reputation: 123

bash script unable to ask confirmation

I am initiating myself to shell scripting and I need to ask the user about confirmation.

I have this script, which I don't know why the following command is not working: read -p "Are you sure about this action?" yn

I use it twice, at the beggining of the script and in the middle. The first read works, but the second one... is not wrking...

Btw, my linux distribution is debian 9.3

#!/bin/bash

read -p "holaaa" yn #HERE THE COMMAND WORKS AS EXPECTED

if [[ -e "$1" && -f "$1" ]]; then
        while read nom grup permisos fitxer; do
                if [ -e $fitxer ]; then
                        #echo $fitxer
                        #f=$(stat -c %n $fitxer)        #jo voldria fer servir awk...
                        u=$(stat -c %U $fitxer)
                        g=$(stat -c %G $fitxer)
                        p=$(stat -c %a $fitxer)
                        if [[ "$p" != "$permisos" || "$u" != "$nom" || "$g" != "$grup" ]]; then
                                echo "Informacio al fitxer: $nom , $grup, $permisos, $fitxer"
                                echo "Informacio real: $u, $g, $p, $fitxer"
                                #posar confirmation
                                read -p "holaaaa" yn #HERE THE COMMAND IS NOT WORKING
                                chown $u:$g $fitxer
                                chmod $permisos $fitxer
                        fi
                else 
                        echo "file $fitxer does not exist"
                fi
        done < "$1"

else
        echo "error" >&2
fi

Does anyone know why this happens or what am I doing wrong?

Upvotes: 1

Views: 314

Answers (2)

Dzienny
Dzienny

Reputation: 3417

The read inside the loop is reading from the same source the condition is (< "$1").

And the prompt is not displayed because it is only showed when input is coming from a terminal.

You can explicitly make the inner read to read from the terminal by adding < /dev/tty, example:

read -p "holaaaa" yn < /dev/tty

Or you can just can read from the standard input with <&0 redirection (file descriptor 0 is for stdin). This has the advantage that the caller of the command will be able to provide canned responses, as noted by the commenter. Example:

read -p "holaaaa" yn <&0

Upvotes: 5

chepner
chepner

Reputation: 531115

You have two read commands intended to read from different sources (one from a given file, the other from the script's standard input), using the same file descriptor (0). Use a different file descriptor for $1 so that the other read can continue to read from the script's standard input, instead of overwriting that with $1.

#!/bin/bash

read -p "holaaa" yn

if [[ -f "$1" ]]; then
    # Read from file descriptor 3
    while read nom grup permisos fitxer <&3; do
         if [ -e "$fitxer" ]; then
             #f=$(stat -c %n $fitxer)        #jo voldria fer servir awk...
             u=$(stat -c %U $fitxer)
             g=$(stat -c %G $fitxer)
             p=$(stat -c %a $fitxer)
             if [[ "$p" != "$permisos" || "$u" != "$nom" || "$g" != "$grup" ]]; then
                 echo "Informacio al fitxer: $nom , $grup, $permisos, $fitxer"
                 echo "Informacio real: $u, $g, $p, $fitxer"
                 #posar confirmation
                 read -p "holaaaa" yn
                 chown $u:$g $fitxer
                 chmod $permisos $fitxer
             fi
         else 
             echo "file $fitxer does not exist"
         fi
    done 3< "$1"  # Attach $1 to file descriptor 3
else
    echo "error" >&2
fi

Upvotes: 2

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