whiptail require three numbers before continuing I have this whiptail form that prompts for user input. Is there a way to force someone to enter three numbers, before allowing him to continue? NUMBERS=$(whiptail --inputbox "Enter three numbers only" 8 78 000 --title "Three Numbers" 3>&1 1>&2 2>&3) exitstatus=$? if [ $exitstatus = 0 ]; then echo "User selected Ok and entered " $NUMBERS else echo "User selected Cancel." fi echo "(Exit status was $exitstatus)"

You can check what the user entered and run your `whiptail` in a loop until they enter a valid value:


#!/usr/bin/env bash

## I included the 000 in the regex below since
## you are populating your field with it. I assume you
## want 000 + 3 numbers.
until [[ $numbers =~ ^000[0-9]{3}$ ]]; do
numbers=$(whiptail --inputbox "Enter three numbers only" 8 78 000 --title "Three Numbers" 3>&1 1>&2 2>&3)
exitstatus=$?
if [ $exitstatus = 0 ]; then
echo "User selected Ok and entered " $numbers
else
echo "User selected Cancel."
break;
fi
done

echo "(Exit status was $exitstatus)"


Note that I also changed the `NUMBERS` to `numbers`. As a general rule, avoid capital variable names in bash scripts since the global environment variables are in caps and that can lead to confusion.