--- a/mcbot/libs/shcmd.lua	Mon Apr 19 10:20:28 2010 +0200
+++ b/mcbot/libs/shcmd.lua	Sat Apr 24 10:45:00 2010 +0200
@@ -6,6 +6,7 @@
     local fh = io.popen(fullcmd)
     result = fh:read("*a")  -- read cmd output
     fh:close()
+    if not result then return nil end
     -- Trim trailing newlines
     local r = result:gsub("\n+$", "")
     return r