read-verification alternative (two prompts and if-then comparison alternative)

Question

I am trying to create a small script for creating simple, all-default Apache virtual host files (it should be used any time I establish a new web application).

This script prompts me for the domain.tld of the web application and also for its database credentials, in verified read operations:

read -p "Have you created db credentials already?" yn
case $yn in
    [Yy]* ) break;;
    [Nn]* ) exit;;
    * ) echo "Please create db credentials and then comeback;";;
esac

read -p "Please enter the domain of your web application:" domain_1 && echo
read -p "Please enter the domain of your web application again:" domain_2 && echo
if [ "$domain_1" != "$domain_2" ]; then echo "Values unmatched. Please try again." && exit 2; fi

read -sp "Please enter the app DB root password:" dbrootp_1 && echo
read -sp "Please enter the app DB root password again:" dbrootp_2 && echo
if [ "$dbrootp_1" != "$dbrootp_2" ]; then echo "Values unmatched. Please try again." && exit 2; fi

read -sp "Please enter the app DB user password:" dbuserp_1 && echo
read -sp "Please enter the app DB user password again:" dbuserp_2 && echo
if [ "$dbuserp_1" != "$dbuserp_2" ]; then echo "Values unmatched. Please try again." && exit 2; fi

Why I do it with Bash

As for now I would prefer Bash automation over Ansible automation because Ansible has a steep learning curve and its docs (as well as some printed book I bought about it) where not clear or useful for me in learning how to use it). I also prefer not to use Docker images and then change them after-build.

My problem

The entire Bash script (which I haven't brought here in its fullness) is a bit longer and the above "heavy" chuck of text makes it significantly longer - yet it is mostly a cosmetic issue.

My question

Is there an alternative for the verified read operations? A utility that both prompts twice and compares in one go?

Related: The need for $1 and $2 for comparison with an here-string

Answer 1

How about a shell function? Like

function read_n_verify  {
    read -p "$2: " TMP1
    read -p "$2 again: " TMP2
    [ "$TMP1" != "$TMP2" ] &&
    { echo "Values unmatched. Please try again."; return 2; }
    read "$1" <<< "$TMP1"
}
read_n_verify domain "Please enter the domain of your web application" 
read_n_verify dbrootp "Please enter the app DB root password" 
read_n_verify dbuserp "Please enter the app DB user password"

Then do your desired action/s with $domain, $dbrootp, $dbuserp.

$1 is used to transport the variable name for the later read from the "here string", which in turn is used as it's easier here than a (could be used as well) "here document".

$2 contains the prompt (free) text, used last to allow for (sort of) "unlimited" text length.

Upper case TMP and [ ... ] && "sugar-syntax" (whatever this might be) are used by personal preference.

if - then - fi could be used as well and would eliminate the need for the braces that collect several commands into one single command to be executed as the && branch.

Answer 2

I would do it like this:

#!/bin/bash
while [[ $string != 'string' ]] || [[ $string == '' ]] 
do
    read -p "Please enter the domain of your web application: " string
    echo "Please enter the domain of your web application: "
done 
Command 1
Command 2

Less typing.

Of course you would need a section like this for all of your questions.

Other than the way you have it and the way I have it, not really any more options.