set search path for exec spawn and popen in ruby

Question

Suppose there is executable /path/to/hello. I want to do this

set-search-path "/path/to:/another/path:/usr/bin:/bin"
IO.popen({},[["hello","argv0"],"argv1"])

I know we can specify full path for "hello", but prefer to see a solution with search path if possible.

Also setting the path prior to invocation of ruby interpreter is not what I'm looking for.

I guess this involves setting the environment of ruby itself, thus maybe a wrapper around the setenv(3) c library function can do.

Please also point out what if I use popen the other way, passing a string to the shell.

I'm currently running ruby2.1.

Answer 1

You can do it like this:

paths = "/path/to:/another/path:/usr/bin:/bin"
paths.split(':').each{|path|
  if File.exist?(path)
    IO.popen(...)
    break
  end
end

Please also point out what if I use popen the other way, passing a string to the shell.

The popen method can accept an environment hash, such as:

IO.popen({'PATH' => '/path/to:/another/path:/usr/bin:/bin'}, cmd)