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HOW TO ADD PROMPT BOX CONFIRMATION IN BASH
2024-06-15 03:30PM • 12 min read • #cli #bash #linux
Yo, what's up ? It's me again, with a #uselesstech linux/bash tips for you.
Creating a prompt confirm feature in Bash(or shell scripting in general) is essential for scripts that require user confirmation before executing 'critical' actions.This feature can help prevent accidental commands that might disrupt systems or cause data loss (since most of them ar irreversible).In this tutorial, we'll build a _confirm function in Bash that prompts the user for confirmation and executes a command based on their response. We'll also explain each part of the function step by step and provide examples of how to use it.
INTRODUCTION TO my _confirm FUNCTION
The _confirm function is a method i made myself and i use it everytime when composing conditionals operations, it takes a message as input and, based on the user's response, executes a command. It also includes a non-interactive mode for automated scripts. Here is the complete _confirm function, followed by a detailed explanation of each part:
# Usage :
# Ex : _confirm "Message" echo "test"
_confirm(){
args=("${@}")
if [[ $NOTINTERACTIVE = "1" ]]; then
echo "[+] ${args[0]} "
callback=${args[@]:1}
$callback
else
echo "[-] ${args[0]} "
read -p "[?] (Y/y): " -n 1 -r
if [[ $REPLY =~ ^[Yy]$ ]]
then
callback=${args[@]:1}
$callback
echo "-------------------------------------------"
return 0
fi
return 1
fi
echo
}
DETAILED EXPLANATIONS
STEP 1: DEFINE THE FUNCTION AND HANDLE ARGUMENTS
$ args=("${@}")
The _confirm function starts by capturing all arguments passed to it using "${@}", storing them in an array called args.
STEP 2: CHECK FOR NON-INTERACTIVE MODE
$ if [[ $NOTINTERACTIVE = "1" ]]; then
This line checks if the NOTINTERACTIVE variable is set to 1. This variable is used to bypass user confirmation, allowing the function to run non-interactively, which is useful for automated scripts.
STEP 3: EXECUTE THE COMMAND IN NON-INTERACTIVE MODE
$ callback=${args[@]:1}
$ $callback
Here, the function extracts the command to be executed from the arguments, starting from the second argument (${args[@]:1}), and stores it in the callback variable. It then executes the command stored in callback.
STEP 4: READ USER INPUT FOR CONFIRMATION
$ read -p "[?] (Y/y): " -n 1 -r
The read command prompts the user for input with the message "[?] (Y/y): " and waits for a single character input (-n 1). The user's input is stored in the REPLY variable.
STEP 5: CHECK USER RESPONSE AND EXECUTE COMMAND
$ if [[ $REPLY =~ ^[Yy]$ ]]; then
callback=${args[@]:1}
$callback
echo "-------------------------------------------"
return 0
If the user's input matches Y or y (using a regular expression [[ $REPLY =~ ^[Yy]$ ]]), the function extracts the command from the arguments and executes it. It then prints a separator line and returns 0 indicating success.
STEP 6: HANDLE NEGATIVE RESPONSE
$ return 1
If the user's input does not match Y or y, the function returns 1, indicating that the command was not executed.
EXAMPLES OF USING THE _confirm FUNCTION
Here are some examples of how you can use the _confirm function in your Bash scripts:
EXAMPLE 1: DOWNLOADING A FILE
$ filename="life.zip"
$ selected_link="http://internet.com/life.zip"
$ _confirm "> Download $filename?" wget $selected_link
In this example, the _confirm function prompts the user with the message "> Download example_file.txt?" If the user confirms by typing Y or y, the script executes the wget command to download the file from the specified link.
EXAMPLE 2: INSTALLING A PACKAGE
$ package_name="curl"
$ _confirm "> Install $package_name?" sudo apt-get install -y $package_name
Here, the function prompts the user with the message "> Install curl?" If the user confirms, the script runs the command to install the curl package using apt-get.
EXAMPLE 3: DELETING A DIRECTORY
$ directory="/path/to/directory"
$ _confirm "> Delete directory $directory?" rm -rf $directory
In this example, the function prompts the user with the message "> Delete directory /path/to/directory?" If the user confirms, the script deletes the specified directory using rm -rf.
DEMO
CONCLUSION
The _confirm function in Bash is a versatile tool i made myself for adding confirmation prompts on scripts, that you can adapt for your needs.It handles both interactive and non-interactive modes, ensuring that user confirmation is sought only when needed. By following the step-by-step breakdown, you can customize and enhance this function to fit your specific requirements, adding a layer of safety to your Bash scripts.
With this guide, you should now be able to implement a prompt confirm feature in your own Bash scripts, making them more robust and user-friendly.
Don't forget to leave a reaction or a comment if you have any question or suggestion.Thanks for reading and Happy scripting :)