From: "ara.t.howard" <ara.t.howard@...>
Date: 2007-06-14T23:30:51+09:00
Subject: Re: using ` and the bash source command


On Jun 10, 2007, at 9:56 PM, Kevin Jackson wrote:

> Hi,
>
>> If you were to run your Java program itself from ruby, I would think
>> that you could set the JAVA_HOME environment variable directly with
>>    ENV[JAVA_HOME] = whatever you want, before executing Java as a
>> child process of the Ruby program.
>
> I cannot run the Java code from the ruby program as I could be running
> one of several apps.
>
> I actually got the behaviour I wanted by writing to .bashrc instead of
> .bash_profile, so now my workflow is:
> - run jdk_switcher -> open terminal -> run cli java app
> instead of:
> - vi .bashrc -> modify JAVA_HOME -> open new terminal -> run cli  
> java app.
>
> It's a hell of a lot quicker than manually editing each time and I'm
> fairly happy with the results and there's no need for the source
> command at all as the .bashrc is read every time I open a new terminal
>
> Anyway, thanks for the help/suggestions
>
> Kev

kevin-

you can do all of this and more with session.  the fundemental  
difference with session is that it uses the SAME bash process for all  
commands, therefore any environments commands, and even bash builtins  
will all works.  for example:


cfp:~ > cat a.rb
require 'time'
require 'rubygems'
require 'session' ### sudo gem install session

### we'll use this single bash instance for everthing
bash = Session::Bash.new

home = File.expand_path '~'

Dir.chdir home do
   4.times do
     ### alter the .bashrc, setting an environment var
     open('.bashrc', 'a+') do |fd|
       lines = fd.readlines
       lines.delete_if{|line| line =~ %r/^export FOO=/}
       lines << "export FOO=#{ Time.now.iso8601(2) }"
       fd.write lines
     end

     ### source it, now bash will pick up the environment var
     bash.execute 'source .bashrc'

     ### run a command that uses the environment, this could be java
     out, err = bash.execute 'echo "FOO: $FOO"'
     puts out
   end
end


cfp:~ > ruby a.rb
FOO: 2007-06-14T08:27:22.90-06:00
FOO: 2007-06-14T08:27:22.93-06:00
FOO: 2007-06-14T08:27:22.96-06:00
FOO: 2007-06-14T08:27:22.98-06:00


-a
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