How do I prompt for input in a Linux shell script?

Question

I want to pause input in a shell script, and prompt the user for choices. The standard 'Yes, No, or Cancel' type question. How do I accomplish this at a typical bash prompt?

Answer 1

echo "Please enter some input: "
read input_variable
echo "You entered: $input_variable"

Answer 2

inquire ()  {
  echo  -n "$1 [$2/$3]? "
  read answer
  finish="-1"
  while [ "$finish" = '-1' ]
  do
    finish="1"
    if [ "$answer" = '' ];
    then
      answer=""
    else
      case $answer in
        y | Y | yes | YES ) answer="y";;
        n | N | no | NO ) answer="n";;
        *) finish="-1";
           echo -n 'Invalid response -- please reenter:';
           read answer;;
       esac
    fi
  done
}

... other stuff

inquire ""Install now? " "y" "n"

...

Where'd my formatting go? I guess that shows what happens if you cut and paste from unix text.

Answer 3

The simplest and most widely available method to get user input at a shell prompt is the 'read' command. The best way to illustrate its use is a simple demonstration:

while true; do
    read -p "Do you wish to install this program?" yn
    case $yn in
        [Yy]* ) make install; break;;
        [Nn]* ) exit;;
        * ) echo "Please answer yes or no.";;
    esac
done

Another method, pointed out by Steven Huwig, is bash's 'select' command. Here is the same example using select:

echo "Do you wish to install this program?"
select yn in "Yes" "No"; do
    case $yn in
        Yes ) make install; break;;
        No ) exit;;
    esac
done

With select you don't need to sanitize the input... it prompts you with your choices, and you type a number corresponding to the choice you want. Select also loops automatically... there's no need for a 'while true' loop to retry if they give invalid input.

Answer 4

I suggest you use dialog... it's simple and easy to use, there's also a gnome version called gdialog that takes the exact same parameters, but shows it GUI style on X.

Answer 5

Bash has select for this purpose.

select result in Yes No Cancel
do
    echo $result
done