From: David Masover <ninja@...>
Date: 2009-08-08T07:53:59+09:00
Subject: Re: how to "source" a file?

On Friday 07 August 2009 02:55:11 pm Glenn Jackman wrote:
> Since Ruby is not Bash, you have to parse the file:
>
>     File.foreach("myenv") do |line|
>       line.chomp.scan(/^export (.+?)=(.*)$/) do |name, val|
>         ENV[name] = val
>       end
>     end
>
>     p ENV['FOO']  # => "bar"

That's pretty fragile -- it would severely limit what you can put in the file.

There are a few ways of doing this, depending on your goal. One would be to 
run a bash (or better yet, sh) script as a wrapper around your Ruby script -- 
that is, if your command is installed as /usr/local/bin/foo, have it be a 
shell script which does this:

#!/bin/sh
. ~/.myenv
exec /usr/lib/foo/foo.rb $@

Another hack I've used, when I wasn't sure whether or not I'd need those 
variables, is to have bash execute the file, and then tell me. If you only need 
one variable, this is easy:

ENV['FOO'] = `source ~/.myenv && echo -n $FOO`

If you wanted all of the variables, here's one (clumsy) way to do it without 
having to (really) parse anything:

require 'yaml'
s = `source ~/.myenv && ruby -e 'require "yaml"; print ENV.to_hash.to_yaml`
Yaml.load(s).each_pair{|k,v| ENV[k]=v}

I realize I could've made that less ugly, but I'm not sure there's a good way 
to make it pretty. It's essentially the same as extracting a single variable, 
except that it invokes another Ruby interpreter to dump the entire environment 
as a yaml stream. I did this because it's a lot easier to just throw the yaml 
parser at the problem than try to parse the output of something like 'env' -- 
I couldn't even figure out which environment variables existed, otherwise.

About the only way I could "improve" it is by streaming that Yaml 
generation/parsing, but if anyone has an environment big enough for it to 
matter, they've already got problems.

One final way would be to add a 'source ~/.myfile' to any other programs you try 
to run -- since you mentioned EDITOR, I'm assuming that's why.