Question

Can ruby lookup path to a binary like in bash or gnu makefile?

Makefile

which node

bash

user@host:~$ which node

Answer thanks Senthess

ruby

needs some code cleanup

def which(*args)
  ret = []
  args.each{ |bin|
    possibles = ENV["PATH"].split( File::PATH_SEPARATOR )
    possibles.map {|p| File.join( p, bin ) }.find {|p|  ret.push p if File.executable?(p) } 
  }
  ret
end

usage

which 'fakebin', 'realbin', 'realbin2'
=> /full/path/realbin
=> /full/path/realbin2

Actually which returns one line for each. This returns an array rather than a string, maybe better, maybe not.

see answer below for which that checks single input

Answer 1

Yes. Something like this:

def which(binary)
   ENV["PATH"].split(File::PATH_SEPARATOR).find {|p| File.exists?( File.join( p, binary ) ) }
end

Explanation:

We access the variable PATH, and we split it according to the platform separator ( : for Unix systems, ; for Windows ). This will yield an array of paths. We then search for the first having a file with name matching the one provided as an argument.

EDIT: If you want the full path, here’s another way of implementing it:

def which(binary)
   possibles = ENV["PATH"].split(File::PATH_SEPARATOR)
   possibles.map {|p| File.join( p, binary ) }.find {|p| File.exists?(p) && File.executable?(p) }
end

EDIT2: updated original code to add executable check. You could implement it like this:

def which_multiple(*args)
    args.map {|e| which(e)}
end