Question

Say I have a web application, with some sort of system execution. I’m going to use Ruby for this example. This app could be portable and installed on either a Windows or Unix server. If the app uses system commands, is there a way to distinguish what platform the server is, then maybe catch in an if statement?

Theoretically like this:

os_check = `checkos` # System ticks to execute through the shell
                     # using fake command

if os_check == 'unix'
  # Run Unix Commands
  `ls -la`
else if os_check == 'dos'
  # Run DOS commands
  `dir`
else
  puts 'OS not detectable'
end

EDIT

I’m not looking for Ruby specifically (removed the tag). That was an example. I was hoping for a shell command that could execute in both environments and be variable based on what the OS is. I actually have to replicate this sort of function in several languages. Sorry for any confusion.

Answer 1

Try checking the RUBY_PLATFORM global constant:

case RUBY_PLATFORM
  when /win32/ then # Windows, use "dir"
  # when /darwin/ then # Mac OS X
  # when /linux/ then # Linux
  else # Assume "ls" on all other platforms
end

[Edit] Per your updated question, you might be able to issue the system command echo /? and parse the output to determine the host OS. The “echo” command should exist on most systems but Windows interprets the /? switch as the “help” message whereas UNIX OSes simply echo those characters. For example (again in Ruby, just to demonstrate the general strategy):

def detect_host_operating_system
  (%x{echo /?} =~ /^\/\?\r?\n$/) ? 'unix' : 'windows'
end