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
– Amadan, Commented Mar 10, 2016 at 4:50

Community · Accepted Answer · 2017-05-23 11:45:19Z

2

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.

edited May 23, 2017 at 11:45

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answered Mar 10, 2016 at 4:58

peak

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1 Comment

sonoluminescence Over a year ago

Thanks I'll give it a try.

user1934428 · Accepted Answer · 2016-03-10 08:13:07Z

1

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.

answered Mar 10, 2016 at 8:13

user1934428

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