How to pass shell script variables back to ruby?

Question

I have a ruby script executing a shell script. How can I pass shell script data back to the ruby script.

      desc "Runs all the tests"
      lane :test do 

        sh "../somescript.sh"

        print variables_inside_my_script // i want to access my script data here.

      end

I'm able to do the reverse scenario using environment variables from ruby to shell script.

      desc "Runs all the tests"
      lane :test do 

        puts ENV["test"]

        sh "../somescript.sh" // access test using $test

      end

Thanks

Not possible. Subprocesses inherit a copy of the parent's environment; they can't affect the parent's environment. If you want to pass data from a shell script to the calling process, the easiest way to do it is through its output. — Amadan, Mar 10 '16 at 04:50

score 2 · Answer 1 · edited May 23 '17 at 11:45

It's not so clear what variables_inside_my_script is supposed to mean here, but as a rule operating systems do not allow one to "export" variables from a subshell to the parent, so rubyists often invoke the subcommand with backticks (or equivalent) so that the parent can read the output (stdout) of the subshell, e.g.

output = %x[ ls ]

There are alternative techniques that may be useful depending on what you really need -- see e.g.

Thanks I'll give it a try. – sonoluminescence Mar 10 '16 at 05:25 — sonoluminescence, Mar 10 '16 at 05:25

score 1 · Answer 2 · answered Mar 10 '16 at 08:13

If the shell script is under your control, have the script write the environment definitions in Ruby syntax to STDOUT. Within Ruby, you eval the output:

eval `scriptsettings.sh`

If your script produces other output, write the environment definitions to a temporary file and use the load command to read them.

How to pass shell script variables back to ruby?

2 Answers2