How to ask user input again and get new value if validation fails?

Question

In my program I need to validate user input getting by "read" in shell script. It check user input has spaces and if validation fails we should give user a another chance to input again.

stringValidator() {  
  if [[ ${1} =~ " " ]]; then
    echo Should not contain spaces
    echo Enter Again!    
    read input
    echo $2=$input 
    return $2   
  else 
    return $1  
  fi
}


echo "Enter below details"
echo -e "client-id :"
read clientId
stringValidator "$clientId" ${!clientId@}

Here I tried to do was send the variable name also into stringValidator() and reassign value to that name (here it is clientId).

But the problem is I can't return that variable from stringValidator(). I use many read inputs though I showed only one here. Therefore I need a separate function for validation.

If you have better way to do this please mention.

Andre Gelinas · Accepted Answer · 2019-10-02 16:01:06Z

1

The statement "return" is not used like that, it's to send back an error code (numerical).

That code should do what you want though :

#!/bin/bash

echo "Enter below details"

while true; do
    echo -n "client-id : "
    read clientID
    if [[ $clientID =~ " " ]]; then
        echo "ClientID Should not contain spaces"
        continue
    else
        break
    fi
done

echo "do something else"

EDIT

To answer your comment, this code in ksh would do what you ask :

#!/bin/ksh

function stringValidator
{

typeset locVarName
typeset locVar

locVarName=$1
nameref locVar=$1

while true; do
    if [[ $locVar =~ " " ]]; then
        echo "$locVarName should not contain spaces"
        echo -n "$locVarName : "
        read locVar
        continue
    else
        break
    fi
done
}

echo "Enter below details"
echo -n "Client-ID : "
read clientId
stringValidator "clientId"
echo "Final value is $clientId"

echo "do something else"

Running would result to something like that :

Enter below details
Client-ID : test t
clientId should not contain spaces
clientId : tesgg
Final value is tesgg
do something else

Hope it helps !

edited Oct 2, 2019 at 16:01

answered Oct 2, 2019 at 12:33

Andre Gelinas

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8 Comments

Gayath_chandi Over a year ago

But the problem is I use many read inputs to validate. I showed here only one as it is easy to understand. I need a separate function for validation.

Andre Gelinas Over a year ago

Well, that would be easy with indirect referencing, but Bash doesn't support it (well 4.3 supposed to but can't test it). Ksh do support it though if you can use that shell on your system.

Gayath_chandi Over a year ago

Can't use that. This script is use for multiple users. This need to work on ubuntu shell.

Andre Gelinas Over a year ago

Just to be sure, with the shebang the script may run within ksh even if your users are on bash. But like I said, having a function to do what you want will be very difficult without the indirect referencing. The other way is to write the while loop for each entry that requires a validation.

Gayath_chandi Over a year ago

Can you give me a example code using indirect referencing for this problem?

|

Javier Mendoza · Accepted Answer · 2019-10-02 13:00:28Z

0

Separate Validation function from read input. Next, introduce it into a while loop to ask for enter input again up to a correct value. Use ECHO instead of RETURN to get the value from a function.

answered Oct 2, 2019 at 13:00

Javier Mendoza

11 bronze badge

2 Comments

John Kugelman Over a year ago

Can you include some code? Code speaks louder than words.

Gayath_chandi Over a year ago

I use many read inputs though I showed only one here. Therefore I need a separate function for validation.

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