How to create dialog boxes in an interactive shell script

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When you install new software in the terminal environment, you may often see informative dialog boxes popping up, accepting your input. The type of dialog boxes ranges from simple yes/no dialog to input box, password box, checklist, menu, and so on. The advantage of using such user-friendly dialog boxes is obvious as they can guide you to enter necessary information in an intuitive fashion.

When you write an interactive shell script, you can actually use such dialog boxes to take user's input. Pre-installed on all modern Linux distributions, a program called whiptail can streamline the process of creating terminal-based dialogs and message boxes inside a shell script, similar to how Zenity or Xdialog codes a GUI for scripts.

In this tutorial, I describe how to create user-friendly dialog boxes in a shell script by using whiptail. I also show Bash code snippets of various dialog boxes supported by whiptail.

Create a Message Box

A message box shows any arbitrary text message with a confirmation button to continue.

whiptail --title "" --msgbox ""  

Example:

#!/bin/bash
shopt -s -o nounset

whiptail --title "Test Message Box" --msgbox "Create a message box with whiptail. Choose Ok to continue." 10 60

Create a Yes/No Box

One common user input is Yes or No. This is when a Yes/No dialog box can be used.

whiptail --title "" --yesno ""  

Example:

#!/bin/bash

shopt -s -o nounset
if (whiptail --title "Test Yes/No Box" --yesno "Choose between Yes and No." 10 60) then
    echo "You chose Yes. Exit status was $?."
else
    echo "You chose No. Exit status was $?."
fi

Optionally, you can customize the text for Yes and No buttons with "--yes-button" and "--no-button" options.

Example:

#!/bin/bash

shopt -s -o nounset
if (whiptail --title "Test Yes/No Box" --yes-button "Skittles" --no-button "M&M's" --yesno "Which do you like better?" 10 60) then
    echo "You chose Skittles Exit status was $?."
else
    echo "You chose M&M's. Exit status was $?."
fi

Create a Free-form Input Box

If you want to take any arbitrary text input from a user, you can use an input box.

whiptail --title "" --inputbox ""   

Example:

#!/bin/bash

shopt -s -o nounset
PET=$(whiptail --title "Test Free-form Input Box" --inputbox "What is your pet's name?" 10 60 Wigglebutt 3>&1 1>&2 2>&3)

exitstatus=$?
if [ $exitstatus = 0 ]; then
    echo "Your pet name is:" $PET
else
    echo "You chose Cancel."
fi

Create a Password Box

A password box is useful when you want to take a sensitive input from a user.

whiptail --title "" --passwordbox ""  

Example:

#!/bin/bash

shopt -s -o nounset

PASSWORD=$(whiptail --title "Test Password Box" --passwordbox "Enter your password and choose Ok to continue." 10 60 3>&1 1>&2 2>&3)

exitstatus=$?
if [ $exitstatus = 0 ]; then
    echo "Your password is:" $PASSWORD
else
    echo "You chose Cancel."
fi

Create a Menu Box

When you want to ask a user to choose one among any arbitrary number of choices, you can use a menu box.

whiptail --title "

	" --menu ""   
	
		[   ] . . .

	

Example:

#!/bin/bash

shopt -s -o nounset

OPTION=$(whiptail --title "Test Menu Dialog" --menu "Choose your option" 15 60 4 \
"1" "Grilled Spicy Sausage" \
"2" "Grilled Halloumi Cheese" \
"3" "Charcoaled Chicken Wings" \
"4" "Fried Aubergine" 3>&1 1>&2 2>&3)

exitstatus=$?
if [ $exitstatus = 0 ]; then
    echo "Your chosen option:" $OPTION
else
    echo "You chose Cancel."
fi

Create a Radiolist Dialog

A radiolist box is similar to a menu box in the sense that you can choose only option among a list of available options. Unlike a menu box, however, you can indicate which option is selected by default by specifying its status.

whiptail --title "" --radiolist ""    [    ] . . .

Example:

#!/bin/bash

shopt -s -o nounset

DISTROS=$(whiptail --title "Test Checklist Dialog" --radiolist \
"What is the Linux distro of your choice?" 15 60 4 \
"debian" "Venerable Debian" ON \
"ubuntu" "Popular Ubuntu" OFF \
"centos" "Stable CentOS" OFF \
"mint" "Rising Star Mint" OFF 3>&1 1>&2 2>&3)

exitstatus=$?
if [ $exitstatus = 0 ]; then
    echo "The chosen distro is:" $DISTROS
else
    echo "You chose Cancel."
fi

Create a Checklist Dialog

A checklist dialog is useful when you want to ask a user to choose more than one option among a list of options, which is in contrast to a radiolist box which allows only one selection.

whiptail --title "" --checklist ""    [    ] . . .

Example:

#!/bin/bash

shopt -s -o nounset

DISTROS=$(whiptail --title "Test Checklist Dialog" --checklist \
"Choose preferred Linux distros" 15 60 4 \
"debian" "Venerable Debian" ON \
"ubuntu" "Popular Ubuntu" OFF \
"centos" "Stable CentOS" ON \
"mint" "Rising Star Mint" OFF 3>&1 1>&2 2>&3)

exitstatus=$?
if [ $exitstatus = 0 ]; then
    echo "Your favorite distros are:" $DISTROS
else
    echo "You chose Cancel."
fi

Create a Progress Bar

Another user-friendly dialog box is a progress bar. whiptail reads from standard input a percentage number (0 to 100) and displays a meter inside a gauge box accordingly.
Example: whiptail --gauge ,这里和dialog是不同的,dialog 的命令是dialog --guage. 一字之差．
下面有两个例子：

#!/bin/bash

shopt -s -o nounset

{
    for ((i = 0 ; i <= 100 ; i+=20)); do
        sleep 1
        echo $i
    done
} | whiptail --gauge "Please wait while installing" 6 60 0

#!/bin/bash

shopt -s -o nounset

{
for ((i=1;i<=10;i++))
do
    let I=10*i
    echo $I
    sleep 1
done
echo

for ((i=9;i>=0;i--))
do
    let I=10*i
    echo $I
    sleep 1
done

} | whiptail --gauge "安装进度" 5 60 0

By now, you must see how easy it is to create useful dialog boxes in an interactive shell script. Next time you need to write a shell script for someone, why don't you try whiptail and impress him or her? :-)