Source shell script into environment within a ruby script

Question

If I'm writing a shell script and I want to "source" some external (c-)shell scripts to set up my environment, I can just make calls like this:

source /file/I/want/to/source.csh

I want to replace a shell script that does this with a ruby script. Can I do a similar thing in the ruby script?

Update:

Just tried it with test_script.csh:

#!/bin/csh

setenv HAPPYTIMES True

...and test_script.rb:

#!/usr/bin/env ruby
system "~/test_script.csh"
system "echo $HAPPYTIMES"

Sadly, no HAPPYTIMES as of yet.

Answer 1

This looks like C shell?

You can, but not with source. You need to use eval instead, and the ruby script would need to kick out csh statements.

So this:

eval `/path/to/ruby-script`

Would basically execute ruby-script and then execute (in the shell process) the output of the script.

What you can't do is set the environment using native ruby methods: any changes would be lost when the ruby interpreter exits.

Answer 2

system 'source /file/I/want/to/source.sh'

Not sure that this will do what you want though. It will execute the source command in a subshell. Try it and see it it does what you're after.

Answer 3

You are going to have to write a function to run something like the following, and capture the output ("backtick" operation):

/bin/csh -e '. my_script ; env'

Loop on each line, match against something like

/^(\w+)=(.*)$/

Then use the first match capture as the var name, and the second capture as the var value.

(yes, I'm hedging on the fact that I know Perl way better than Ruby, but the approach would be the same)

Answer 4

The reason this isn't working for you is b/c ruby runs its system commands in separate shells. So when one system command finishes, the shell that had sourced your file closes, and any environment variables set in that shell are forgotten.

If you don't know the name of the sourced file until runtime, then Roboprog's answer is a good approach. However, if you know the name of the sourced file ahead of time, you can do a quick hack with the hashbang line.

% echo sourcer.rb
#!/usr/bin/env ruby
exec "csh -c 'source #{ARGV[0]} && /usr/bin/env ruby #{ARGV[1]}'"
% echo my-script.rb
#!/usr/bin/env ruby sourcer.rb /path/to/file/I/want/to/source.csh
puts "HAPPYTIMES = #{ENV['HAPPYTIMES']}"
% ./my-script.rb
HAPPYTIMES = True

All of these will only help you use the set enviroment variables in your ruby script, not set them in your shell (since they're forgotten as soon as the ruby process completes). For that, you're stuck with the source command.