Prompt if answer is correct then validate in Bash

Question

This is the initial script that is executed during the beginning of the install. It will capture the user input then write it to the another bash script where the variables are called. It works great as is however, I would like to add in a confirmation for each question.

After the user enters the email for example I would like for it to echo back what they typed to confirm it is correct with a yes or no. If yes then write it to the other script and move on to the next question. If not loop back to the beginning of the statement so they can correct the answer. Once completed I would like to echo out the results.

If someone can provide some pointers that would be great. I was looking at these examples In Bash, how to add "Are you sure [Y/n]" to any command or alias?

#!/bin/bash
read -p "Who is the primary Email recipient? : " TO
    echo "TO=$TO" >> /var/tmp/ProcMon
read -p "What is the server hostname : " FROM
    echo "FROM=$FROM" >> /var/tmp/ProcMon

I did see this one, however it simply is a yes or no statement with no loop back if the user selects no it only cancels which I do not need. — JA1, Jun 23 '14 at 15:41

glenn jackman · Accepted Answer · 2014-06-23T20:10:00.640

function prompt_and_confirm {
    local var=$1
    local prompt=$2
    local value
    local -u ans

    while :; do
        read -p "$prompt" value
        read -p "You entered: '$value': confirm [y/n] " ans
        [[ ${ans:0:1} == "Y" ]] && break
    done
    echo "$var=$value"
}

prompt_and_confirm TO   "Who is the primary Email recipient? : " >> /var/tmp/ProcMon
prompt_and_confirm FROM "What is the server hostname? : "        >> /var/tmp/ProcMon

Notes:

local declares variables with function scope.
- It takes the same arguments as declare -- declare the ans variable to be upper case.
- http://www.gnu.org/software/bash/manual/bashref.html#index-declare
while :; do -- the : command is, basically, a no-op that returns success, so this is an infinite loop.
- http://www.gnu.org/software/bash/manual/bashref.html#Bourne-Shell-Builtins
${ans:0:1} extract the substring starting at the zero'th char of length 1 (the first char)
- http://www.gnu.org/software/bash/manual/bashref.html#Shell-Parameter-Expansion

Seriously thank you very much that was clean and minimal exactly what I needed. — JA1, Jun 23 '14 at 16:47
Not to drag this out, but would you be willing to provide a brief explanation of this code so I can learn? — JA1, Jun 23 '14 at 17:20
+1. Note that `local -u` / `declare -u` requires bash 4+; earlier versions can use just `local`, and `[[ $ans =~ ^[yY] ]]` as the conditional. — mklement0, Jun 23 '14 at 21:54

Prompt if answer is correct then validate in Bash

1 Answers1