[Lua5.1] popen and exit code

[jseb <gmane2010@...>]

Hello,

I'd like to get exit code from shell commands executed with «popen».

According to this, it's possible:
http://www.luafaq.org/#T8.2.8

The «close» should return the exit code.

Fine, but there's two problems

#1 : the code returned is a boolean (i thought it would be an integer)

#2 : this boolean is always set to «true», whatever success of command 
shell is.


Here is my try:


#!/usr/bin/env lua

function shell (cmd)
   local f = io.popen (cmd, 'r')
   local buffer = f.read (f,'*a')
   local exit_code = f.close(f)
   return buffer, exit_code
end


buffer, exit_code = shell ("imsurethiscommandisinvalid")
if (exit_code==true) then
   io.write ("ERROR\n")
else
   print (buffer)
end


Thank you.