ruby - Emacs is ignoring my path when it runs a compile command

Question

I'm trying to get a compile command (rake cucumber) to run with a specific ruby version on my Mac OS X system, I use rvm to do this currently in the terminal. My ~/.MacOSX/environment.plist has the correct path in it, but emacs insists on prepending to this path and therefore making it useless. I've also tried:

(when (equal system-type 'darwin)
  (setenv "PATH" (concat "/Users/fearoffish/.rvm/bin:/Users/fearoffish/.rvm/rubies/ruby-1.8.7-p249/bin:/Users/fearoffish/.rvm/gems/ruby-1.8.7-p249/bin:/Users/fearoffish/.rvm/gems/ruby-1.8.7-p249%global/bin:/Users/fearoffish/.rvm/bin"))
  (push "/Users/fearoffish/.rvm/bin" exec-path)
  (push "/Users/fearoffish/.rvm/rubies/ruby-1.8.7-p249/bin" exec-path)
  (push "/Users/fearoffish/.rvm/gems/ruby-1.8.7-p249/bin" exec-path)
  (push "/Users/fearoffish/.rvm/gems/ruby-1.8.7-p249%global/bin" exec-path)
  (push "/Users/fearoffish/.rvm/bin" exec-path))

It was the desperate attempt of an emacs beginner to get what I wanted. It still prepends in front of it, so my path ends up being:

/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin:/Users/fearoffish/.rvm/bin:/Users/fearoffish/.rvm/rubies/ruby-1.8.7-p249/bin:/Users/fearoffish/.rvm/gems/ruby-1.8.7-p249/bin:/Users/fearoffish/.rvm/gems/ruby-1.8.7-p249%global/bin

I don't want /usr/bin and others prepending, I want my path first and the emacs prepended path to be at the end, I reckon this would fix my problem.

I test this by simply opening Aquamacs and running meta-x compile and then echo $PATH.

Any ideas?

Answer 1

Everyone seems to have misunderstood the original issue: the path is already setup correctly in Emacs, and the correct path is already passed to the shell started by the compile command! So what gives? Here is the answer:

In MacOS X, there is a small tool called path_helper(1). It is called by default from /etc/profile, which is executed by Bash on shell startup. When you start a compilation from Emacs, it launches a shell (which by default is Bash on MacOS X), and therefore executes this path_helper tool. And here comes the key point: path_helper rearranges your path, moving the standard directories like /usr/bin in front of your custom added directories, no matter where you originally added them. Try this yourself by opening a shell and first having a look at what PATH is, and then execute /usr/lib/path_helper and have look at the resulting PATH!

The brute force solution for you might be to simply comment out the call to path_helper in /etc/profile. Note however that then you won't automatically get the paths in /etc/paths.d setup by path_helper, which is the tool's main purpose.