On Sat, Jul 28, 2012 at 9:07 AM, leledumbo <leledumbo_cool at yahoo.co.id> wrote: >> does the operating system keep an index somewhere ? > > ls doesn't, find does AFAIK. > "find" doesn't have any index over "ls". You may be thinking of "locate" (actually "located") that keeps a textfile with the list of files. Best regards, Flávio