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


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?



Source: Tips4allCCNA FINAL EXAM

Comments

  1. 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.

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

    ReplyDelete
  3. Since BASH4, you can now suggest an answer (-i), so the user only have to press return to enter it :

    read -e -p "Enter the path to the file: " -i "/usr/local/etc/" FILEPATH

    (remember to use the readline option (-e) to allow line editing with arrow keys)

    ReplyDelete
  4. Bash has select for this purpose.

    select result in Yes No Cancel
    do
    echo $result
    done

    ReplyDelete
  5. read -p "Are you alright? (y/n) " RESP
    if [ "$RESP" = "y" ]; then
    echo "Glad to hear it"
    else
    echo "You need more bash programming"
    fi

    ReplyDelete
  6. Use the read command
    Just do:


    echo Would you like to install? "(Y or N)"

    read x

    if [ "x" = "y"]


    and then all of the other stuff you need

    ReplyDelete
  7. 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.

    ReplyDelete
  8. 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.

    ReplyDelete
  9. 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`


    Hi Christopher,
    I used the above code in one of my bash script, even though it says select Yes or No it won't work if I press "Y" or "YES", rather I have to input "1" to say "YES" or 2 to say "NO", it does what it should on option "1" i.e. rm -rf filname (i am deleting a file after its downloaded and extracted) - once it has deleted it, it doesn't returns to the prompt rather it sits on ?#
    Any ideas ? Your suggestions would be helpful
    Thanks again !

    ReplyDelete

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