On Thu, 2005-05-05 at 07:58, T. Horsnell wrote: > Oops, I spoke too soon... > > On my system: > > [root@ls1 ~]$ df -k /testnfs > Filesystem 1K-blocks Used Available Use% Mounted on > /dev/sdd1 35280616 11836988 21651476 36% /testnfs > [root@ls1 ~]$ time tar cf - -C /testnfs . > /dev/null > 0.074u 0.000s 0:00.07 100.0% 0+0k 0+0io 0pf+0w > [root@ls1 ~]$ time tar cf /dev/null -C /testnfs . > 0.075u 0.000s 0:00.07 100.0% 0+0k 0+0io 0pf+0w > > [root@ls1 ~]$ df -k /nfs/server1/www > Filesystem 1K-blocks Used Available Use% Mounted on > server1:/www 35278544 11923576 21562920 36% /nfs/server1/www > [root@ls1 ~]$ time tar cf - -C /nfs/server1/www . > /dev/null > 0.303u 1.739s 0:08.73 23.2% 0+0k 0+0io 0pf+0w > [root@ls1 ~]$ time tar cf /dev/null -C /nfs/server1/www . > 0.294u 1.333s 0:16.00 10.1% 0+0k 0+0io 0pf+0w > > [root@ls1 ~]$ tar --version > tar (GNU tar) 1.14 > Copyright (C) 2004 Free Software Foundation, Inc. > This program comes with NO WARRANTY, to the extent permitted by law. > You may redistribute it under the terms of the GNU General Public License; > see the file named COPYING for details. > Written by John Gilmore and Jay Fenlason. > > Les, is this *meant* to work as you say, or is it something > which just happened to work (once upon a time)? If its meant > to work, perhaps I should contact the Gnutar maintainers... It's intended to let the --totals option work as quickly as possible, but now I remember it is even smarter. It is comparing it's output fd inode to that of /dev/null so even the redirection triggers the 'directory only' mode. If you look at your file access times you'll see that they weren't really read. You have to do something like 'tar cf - . |cat >/dev/null' to make it actually read the files and throw away the data. -- Les Mikesell les@xxxxxxxxxxxxxxxx
