How to send commands to the ruby interpreter from a Shell Script?

Question

This is more out of curiosity... I’ve seen some examples of what I want to do, but in Perl. I tried to find a way to do the same in Ruby, but to no avail.

I want a function to generate an MD5 hash from a passed word as argument. The intention is to send this argument to the ruby interpreter, and then use the return in the function. I made a "pseudo-code" to illustrate what I want:

function generate_hash {
  # Enviar o argumento para o interpretador e obter o retorno.
  ruby "Digest::MD5.hexdigest($1)"
}

Does anyone have any idea how I could make this integration?

Answer 1

To execute a direct command in the Ruby interpreter use -e, in short your example would be:

#!/bin/bash
function generate_hash {
  # Enviar o argumento para o interpretador e obter o retorno.
  ruby -e "require 'digest/md5';puts Digest::MD5.hexdigest('$1')"
}
generate_hash $1

Upshot:

⟩ ./test.sh a
0cc175b9c0f1b6a831c399e269772661

Answer 2

A great way is to use I/O to send the data. In bash:

generate_hash() {
  ruby -r digest/md5 -e 'puts Digest::MD5.hexdigest STDIN.read'
}

echo 'argumento' | generate_hash
generate_hash < arquivo