Question

I built a rails deploy dashboard that kicks off a ruby script on a remote machine to update a deployed application.

The command to run the script looks like this:

ssh test-host-02 
  "wget -q -O - http://server/deploy.rb | sudo ruby" 
  > /tmp/update-test-host-02.log 2>&1

Now I need to pass arguments into the deploy.rb script. Such as which build to deploy.

What is the best way to pass arguments to deploy.rb?

Answer 1

Ruby follows the standard convention of allowing you to specify stdin input with -, which allows you to pass arguments after.

$ ruby -- - HELLO
puts ARGV.first # outputs HELLO

The double-dash isn’t necessary in most cases.

Another option is to use turn the output of wget into a file descriptor using bash’s <() operator:

$ ruby <(wget -O - http://example.com/deploy.rb) option1 option2 ...