From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753032AbXCMFsm (ORCPT ); Tue, 13 Mar 2007 01:48:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753022AbXCMFsm (ORCPT ); Tue, 13 Mar 2007 01:48:42 -0400 Received: from vms046pub.verizon.net ([206.46.252.46]:60185 "EHLO vms046pub.verizon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753031AbXCMFsl (ORCPT ); Tue, 13 Mar 2007 01:48:41 -0400 Date: Tue, 13 Mar 2007 01:48:35 -0400 From: Gene Heskett Subject: Re: Stracing Amanda (was: RSDL for 2.6.21-rc3- 0.29) In-reply-to: <20070313044555.GO943@1wt.eu> To: linux-kernel@vger.kernel.org Cc: Willy Tarreau , Nish Aravamudan , Douglas McNaught , Patrick Mau Message-id: <200703130148.36240.gene.heskett@gmail.com> Organization: Organization? very little MIME-version: 1.0 Content-type: text/plain; charset=iso-8859-1 Content-transfer-encoding: 7bit Content-disposition: inline References: <20070311013506.GD10459@waste.org> <200703130004.42854.gene.heskett@gmail.com> <20070313044555.GO943@1wt.eu> User-Agent: KMail/1.9.6 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 13 March 2007, Willy Tarreau wrote: >On Tue, Mar 13, 2007 at 12:04:42AM -0400, Gene Heskett wrote: >> On Monday 12 March 2007, Nish Aravamudan wrote: >> >On 3/12/07, Gene Heskett wrote: >> >> On Monday 12 March 2007, Douglas McNaught wrote: >> >> >Patrick Mau writes: >> >> >> Why not temporarly replace "/bin/tar" with a shell script that >> >> >> does: >> >> >> >> >> >> #!/bin/sh >> >> >> exec strace -f -o output /bin/real.tar $@ >> >> > >> >> >You beat me to it. :) I've done that before; it's a great >> >> > suggestion. >> >> > >> >> >Except that if you expect 'tar' to be invoked multiple times in a >> >> > run, you should probably use 'output.$$' for the output filename >> >> > so things don't get clobbered. >> >> > >> >> >-Doug >> >> >> >> In my case, Doug, it will get invoked 64 times, amanda does a dummy >> >> run to get an estimate, calculates what to do based on that output >> >> which is 32 runs, 1 per disklist entry and I have 32, and then >> >> reruns tar with the appropriate level options against each >> >> individual disklist entry. >> >> >> >> But I'm puzzled a bit, what does the double $$ do?, or it buried >> >> someplace in the bash manpage? Its not something I've stumbled >> >> over yet. >> > >> >buried indeed: >> > >> >"Special Parameters: >> > ... >> > $ Expands to the process ID of the shell. In a () >> > subshell, it expands to the process ID of the current shell, >> > not the sub?$B!> shell. >> >" >> >> Well, that's clear enough, but what of the double $$ case? Would this >> them make a PID unique to each invocation untill it finally wraps a 16 >> bit value, or will the kernel re-use them because they won't all be >> running simultainiously, but limited by the number of unique 'spindle' >> numbers on the system, this to prevent as best as it can, the >> thrashing of a drive by having tar working on 2 separate (or more) >> partitions at the same time. In my case 2 are possible, as /var is on >> a separate drive. > >Yes there a risk of wrapping, but it is very small. You can add the > command line arguments to the file name if you want, like this : > >#!/bin/sh >exec strace -f -o "output.$$.${*//\//_}" /bin/real.tar $@ > >It will name the output file "output..", replacing slashes > with underscores. This is very dirty but can help. > Excellent Willy, thanks. >Cheers, >Willy -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Whatever doesn't succeed in two months and a half in California will never succeed. -- Rev. Henry Durant, founder of the University of California