In Python, you can do
>>> import sys
>>> sys.executable
'/usr/bin/python'
to get at the executable's location. Can you do the same thing just using something built-in to Ruby? It can be a special variable, method, etc.
If there isn't, what is the cleanest, most reliable way of determining the ruby executable's location in a cross-platform way?
Related:
Run this in IRB:
require 'rbconfig'
key_length = RbConfig::CONFIG.keys.max{ |a,b| a.length <=> b.length }.length
RbConfig::CONFIG.keys.sort_by{ |a| a.downcase }.each { |k| puts "%*s => %s" % [key_length, k, RbConfig::CONFIG[k]] }
It will output an "awesome print" style list of all the Ruby configuration info.
ALLOCA =>
AR => ar
arch => x86_64-darwin10.5.0
ARCH_FLAG =>
archdir => /Users/greg/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/x86_64-darwin10.5.0
ARCHFILE =>
AS => as
ASFLAGS =>
BASERUBY => ruby
bindir => /Users/greg/.rvm/rubies/ruby-1.9.2-p0/bin
bindir is the path to the currently running Ruby interpreter. Above it in the list is BASERUBY => ruby.
RbConfig::CONFIG.values_at('bindir', 'BASERUBY').join('/')
=> "/Users/greg/.rvm/rubies/ruby-1.9.2-p0/bin/ruby"
Checking my work:
greg-mbp-wireless:~ greg$ which ruby
/Users/greg/.rvm/rubies/ruby-1.9.2-p0/bin/ruby
There's a lot more information than this so it's worth running the code I added above to see what's available.
Looks like the only truly reliable way is
system("#{Gem.ruby} another_file.rb")
This works even for odd cases like jruby being run as a jar, etc.
Also see
OS.ruby_bin
Linux-based systems are OK with
`whereis ruby`.split(" ")[1]
It will call whereis ruby and parse its' output for the second entry (first contains 'whereis:')
The more strict method is to call
puts `ls -al /proc/#{$$}/exe`.split(" ")[-1]
It will get the executable name for the current process (there is $$ variable and Process.pid method to obtain that) from /proc/pid/exe symlink information.
It looks like the answer is in RbConfig::CONFIG I think RbConfig::CONFIG['bindir'] provides the directory where the executable is located, the rest is s (or should be) straight forward.
RbConfig::CONFIG['bindir']+'/ruby' should work, even in windows as the exe can be ommitted
Works in a script, not from irb:
puts open($PROGRAM_NAME).readline.gsub /#! *([^ ]+).*/, '\1'
;-)
