Re: Stracing Amanda (was: RSDL for 2.6.21-rc3- 0.29)

From: Nish Aravamudan
Date: Mon Mar 12 2007 - 23:01:36 EST


On 3/12/07, Gene Heskett <gene.heskett@xxxxxxxxx> wrote:
On Monday 12 March 2007, Douglas McNaught wrote:
>Patrick Mau <mau@xxxxxxxxxxxxx> 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‐
shell.
"

Thanks,
Nish
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