make-an-executable-ruby-script.md

Make An Executable Ruby Script

In a unix environment with Ruby available, I can make a Ruby script. To do this I stick some code in a Ruby file, like database_url.rb.

result = `heroku pg:credentials:url DATABASE_URL --app my-app`
puts result.split("\n")[2].strip

And then execute that file with ruby:

$ ruby database_url.rb

I can instead make an executable file that doesn't need to be explicitly invoked with the ruby command. To do this, I need to prefix my file with a shebang for ruby.

And I'll even just call the file database_url now, no file suffix.

#!/usr/bin/env ruby

result = `heroku pg:credentials:url DATABASE_URL --app my-app`
puts result.split("\n")[2].strip

When executed, this script will see the first line and understand that it needs to execute the rest of the script using ruby as the interpreter.

Like any other executable, you can call it as is, like so:

$ database_url