Call ruby function from command-line

First the name of the class needs to start with a capital letter, and since you really want to use a static method, the function name definition needs to start with self..

class TestClass    def self.test_function(someVar)        puts "I got the following variable: " + someVar    endend

Then to invoke that from the command line you can do:

ruby -r "./test.rb" -e "TestClass.test_function 'hi'"

If you instead had test_function as an instance method, you'd have:

class TestClass    def test_function(someVar)        puts "I got the following variable: " + someVar    endend

then you'd invoke it with:

ruby -r "./test.rb" -e "TestClass.new.test_function 'hi'"

Here's another variation, if you find that typing ruby syntax at the command line is awkward and you really just want to pass args to ruby. Here's test.rb:

#!/usr/bin/env rubyclass TestClass  def self.test_function(some_var)    puts "I got the following variable: #{some_var}"  endendTestClass.test_function(ARGV[0])

Make test.rb executable and run it like this:

./test.rb "Some Value"

Or run it like this:

ruby test.rb "Some Value"

This works because ruby automatically sets the ARGV array to the arguments passed to the script. You could use ARGV[0] or ARGV.first to get the first argument, or you could combine the args into a single string, separated by spaces, using ARGV.join(' ').

If you're doing lots of command-line stuff, you may eventually have a use for Shellwords, which is in the standard ruby lib.

If you have multiple arguments to call in a example like this:

class TestClass  def self.test_function(some_var1, some_var2)    puts "I got the following variables: #{some_var1}, #{some_var2}"  endend

run it like this (the arguments need to be comma separated in this case)

ruby -r "./test.rb" -e "TestClass.new.test_function 'hi','Mike'"