Pause execution and wait for user input

I have a script that I am making and I have an issue with it: I would like to pause execution and wait for user input. I thought that I had it with the read -p -n 1 $foo command but the system is having issues with this command. Here is my current script:

#!/bin/sh

# Ititialization

mainmenu () {
  echo "Press 1 to update your system"
  echo "Press 2 to install samba"
  echo "Press 3 to install vsFTPd"
  echo "Press 4 to install the current version of Webmin"
  echo "Press 5 to configure samba for Active Directory"
  echo "Press x to exit the script"
  read -n 1 -p "Input Selection:" mainmenuinput
  if [ "$mainmenuinput" = "1" ]; then
            updatesystem
        elif [ "$mainmenuinput" = "2" ]; then
            installsamba
        elif [ "$mainmenuinput" = "3" ]; then
            installvsftpd
        elif [ "$mainmenuinput" = "4" ]; then
            installwebmin
        elif [ "$mainmenuinput" = "5" ]; then
            configuresambaforactivedirectory
        elif [ "$mainmenuinput" = "x" ];then
            quitprogram
        elif [ "$mainmenuinput" = "X" ];then
            quitprogram
        else
            echo "You have entered an invallid selection!"
            echo "Please try again!"
            echo ""
            echo "Press any key to continue..."
            read -n 1
            clear
            mainmenu
        fi
}

# This builds the main menu and routs the user to the function selected.

mainmenu

# This executes the main menu function.
# Let the fun begin!!!! WOOT WOOT!!!!

You may notice at the mainmenu function the read -n 1 -p "text goes here" entry. That is where I am having the issue according to ubuntu. Can somebody tell me what is going wrong? thanks!

Solution 1:

Should be:

read  -n 1 -p "Input Selection:" mainmenuinput

Need to put the n flag after, as that is is telling read to execute after N characters are entered, do not wait for an entire line. Check help read and this for details.