Shell out from ruby while setting an environment variable

Question

I need to shell out to a process while setting an environment variable for it. I tried this one-liner:

system \"RBENV_VERSION=system ruby extconf.rb\"


        

Answer 1

This may work?

system <<-CMD
export VARNAME=123
other_command
CMD

Answer 2

Using your same approach, but wrapped up as a block method that temporarily modifies the environment (like the block form of Dir.chdir):

def with_environment(variables={})
  if block_given?
    old_values = variables.map{ |k,v| [k,ENV[k]] }
    begin
       variables.each{ |k,v| ENV[k] = v }
       result = yield
    ensure
      old_values.each{ |k,v| ENV[k] = v }
    end
    result
  else
    variables.each{ |k,v| ENV[k] = v }
  end
end

with_environment 'RBENV_VERSION'=>'system' do
  `ruby extconf.rb`
end

Answer 3

Ruby 1.9 includes Process::spawn which allows an environ hash to be provided.

Process::spawn is also the foundation for system, exec, popen, etc.
You can pass an environment to each.

Under Ruby 1.8, you may want to consider the POSIX::Spawn library,
which provides the same interfaces

Answer 4

system({"MYVAR" => "42"}, "echo $MYVAR")

system accepts any arguments that Process.spawn accepts.

Answer 5

Actually that worked for me.

shai@comp ~ » irb                                                                                                                                     
1.9.3p0 :001 > system %{SHAIGUITAR=exists ruby -e 'puts ENV["SHAIGUITAR"]'}
exists
 => true 

But if it doesn't, maybe you can try prepending "env" to whatever variable you need. E.g.

system(%{env SHAIGUITAR=exists ruby bla.rb})