How to prompt and read user input in Bash

If we would like to ask the user for input then we use a command called read in our bash scripts. This command takes the input and will save it into a variable.

Here are two slightly different versions of the same shell script. This first version prompts the user for input only once, and then dies if the user doesn’t give a correct Y/N answer:

# (1) prompt user, and read command line argument
read -p "Run the cron script now? " answer

# (2) handle the command line argument we were given
while true
do
  case $answer in
   [yY]* ) /usr/bin/wget -O - -q -t 1 http://www.example.com/cron.php
           echo "Okay, just ran the cron script."
           break;;

   [nN]* ) exit;;

   * )     echo "Dude, just enter Y or N, please."; break ;;
  esac
done

This second version stays in a loop until the user supplies a Y/N answer:

while true
do
  # (1) prompt user, and read command line argument
  read -p "Run the cron script now? " answer

  # (2) handle the input we were given
  case $answer in
   [yY]* ) /usr/bin/wget -O - -q -t 1 http://www.example.com/cron.php
           echo "Okay, just ran the cron script."
           break;;

   [nN]* ) exit;;

   * )     echo "Dude, just enter Y or N, please.";;
  esac
done

This Linux Bash ‘read’ function is nice, because it does both things, prompting the user for input, and then reading the input. We prefer the second approach, but thought we’d share both of them here. They are subtly different, but note the extra break in the first script.