Groovy Scripting and Command-Line Usage

15. Groovy Scripting and Command-Line Usage

// myscript.groovy

def message = "Hello, World!"
println(message)

In this example, we create a simple Groovy script that prints "Hello, World!" to the console.

Running a Groovy Script:

You can execute Groovy scripts from the command line using the 'groovy' command followed by the script's filename.

groovy myscript.groovy

Executing this command will run the 'myscript.groovy' script, and you will see the output "Hello, World!" in the terminal.

Passing Command-Line Arguments:

You can pass command-line arguments to a Groovy script using the 'args' variable.

// myscript.groovy

if (args.length == 0) {
    println("Please provide a name as a command-line argument.")
} else {
    def name = args[0]
    println("Hello, $name!")
}

groovy myscript.groovy Alice

This will print "Hello, Alice!" to the console.

Interactive Mode:

Groovy provides an interactive mode called the Groovy Shell ('groovysh' or 'groovyConsole'), which allows you to execute Groovy code interactively, similar to a REPL (Read-Eval-Print Loop).

groovysh

Once in the Groovy Shell, you can enter Groovy code line by line and see the results immediately.

Script Shebang:

On Unix-based systems (Linux and macOS), you can use a shebang line at the beginning of a Groovy script to make it executable directly from the command line.

#!/usr/bin/env groovy

def message = "Hello, World!"
println(message)

./myscript.groovy

Working with Files:

Groovy scripts can read and write files, making them suitable for various automation tasks.

// readfile.groovy

def filename = args[0]
def file = new File(filename)

if (file.exists()) {
    def content = file.text
    println("File Content:\n$content")
} else {
    println("File not found: $filename")
}

groovy readfile.groovy mydata.txt