Bash script help with if then else and case sensitivity

Question

Ok I'm trying to have a situation where I check if a file exists, if it does then I give the user the option to download it again - I want the default (enter) to be Y, I want Y or y to continue the script, I want N or n to exit the script, and I want all other responses to go back and re-prompt the question... but I'm stuck on that.

What I've done really just continues on (enter), and fails on all other responses other than lowercase y.

Here it is:

if [ -f $target/$remote_backup ];then
    read -p "This file already exists, do you still want to download? [Y/n]" decide
     if [ -z $decide ];then
        # if you press return it'll default to Y and continue
        decide="Y"
    else
        if [ $decide != y ]; then
        echo "Ok you said no or pressed a random button, exiting"
        exit -1
    fi
fi
fi

Ignacio Vazquez-Abrams · Accepted Answer · 2010-11-06 10:59:02Z

4

The usual structure to use for this is case.

case "$decide" in
  y|Y|'') echo "yes" ;;
  n|N) echo "no" ;;
  *) echo "boo" ;;
esac

answered Nov 6, 2010 at 10:59

Ignacio Vazquez-Abrams

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4 Comments

beatbreaker Over a year ago

So that goes after the read? I won't be echoing I don't think, or do I need to in this situation? can i exit -1 if they press n and how can I loop if they answer * ?

Ignacio Vazquez-Abrams Over a year ago

Put it inside a loop. On N, exit. On Y, break.

Ignacio Vazquez-Abrams Over a year ago

Tell the user to enter a valid option.

beatbreaker Over a year ago

I can't get that to ask the user to enter a valid option without kicking them off the script

Frédéric Hamidi · Accepted Answer · 2010-11-06 11:06:17Z

1

Try a while loop:

if [ -f $target/$remote_backup ]; then
    decide="?"
    while [ "$decide" != "y" -a "$decide" != "n" ]; do
        read -p "This file already exists, do you still want to download? [Y/n] " decide
        if [ -z $decide ]; then
            decide="y"
        fi
    done
    echo Decision: $decide
fi

edited Nov 6, 2010 at 11:06

answered Nov 6, 2010 at 10:58

Frédéric Hamidi

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2 Comments

beatbreaker Over a year ago

I don't think I understand, does the while go in after? like this... if [ -f $target/$remote_backup ];then while [ "$decide" != "y" -a "$decide" != "n" ]; do read -p "This file already exists, do you still want to download? [Y/n] " decide if [ -z $decide ]; then decide="y" fi done

Frédéric Hamidi Over a year ago

@beatbreaker, the while goes after your first if. I updated my answer with more context.

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