Use the length operator (#) instead of table.getn.

table.getn was deprecated in Lua 5.1 in favor of #, the length operator.
See: http://www.lua.org/manual/5.1/manual.html#7.2

etc/get.lua

@@ -135,7 +135,7 @@ end
 
 -- main program
 arg = arg or {}
-if table.getn(arg) < 1 then
+if #arg < 1 then
     io.write("Usage:\n  lua get.lua <remote-url> [<local-file>]\n")
     os.exit(1)
 else get(arg[1], arg[2]) end