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Re: [linux-lvm] lvcreate and lvremove --quiet option is not quiet



On Mon, Feb 14, 2011 at 10:31 AM, Ray Morris <support bettercgi com> wrote:
>>  My general scripting philosophy is that automation scripts that
>> do not have errors should not generate output that will cause cron
>> to send an email.
>
>> So... I grabbed the source code and started nosing around.
>
> So we'll look forward to seeing your patches I hope?

This is the first time I've ever even looked at LVM source code. I'm
not sure I can be trusted with patches. Thinking about it some more, I
was wondering if the log_info macro is purely for syslog
functionality.  I could be barking up the wrong tree in terms of my
suggested approach.  I would rather leave this to someone with
experience if the behavior can be agreed upon.

> It does seem logical that it shouldn't produce informational
> messages on stdout with --quiet.
>
> As to the first part, that got me thinking about the general rule.
> Is it generally agreed that commands which do not have errors "should
> not generate output" or that commands which do not have ERRORs "should
> not generate output on standard ERROR?
>
> The OP said that these messages are on stdout, not stderr.  I'm
> kind of thinking that's right. No errors, nothing on standard error.
> If using --quiet, then no standard output.  If lacking a quiet option,
> then cron jobs should redirect stdout to /dev/null, sending mail if
> there are errors on stderr.  Thoughts?
> --
> Ray Morris
> support bettercgi com

I agree completely with your assessment. The only issue I wanted to
raise is that a quiet option is advertised, but it does not get the
job done.

Jeff

> On Mon, 14 Feb 2011 09:46:05 -0600
> Jeff <jlar310 gmail com> wrote:
>
>> Background: I am using lvm snapshots in a backup script. My general
>> scripting philosophy is that automation scripts that do not have
>> errors should not generate output that will cause cron to send an
>> email.
>>
>> I am using Ubuntu 10.04 with lvm2.02.54-1ubuntu4.
>>
>> Even with the --quiet option I get "Logical volume <name> created" on
>> stdout with lvcreate and "Logical volume <name> successfully removed"
>> with lvremove.
>>
>> So... I grabbed the source code and started nosing around. In
>> lv_manip.c, I find that these messages are produced with a call to the
>> function log_print. log_print is a macro (in log.h) for
>> LOG_LINE(_LOG_WARN, args). So it looks like the logging system sees
>> these messages as warnings and is printing them even though verbosity
>> is turned down as far as possible. In addition to --quiet on the
>> command line, I have verbose = 0 in lvm.conf which according to the
>> man page "should produce no output".
>>
>> >From my point of view, lv_manip.c should be calling the log_info
>> >macro
>> for these messages and not log_print, thus giving the user control
>> over the output as advertised by the documentation. Disclaimer: I did
>> not dig into the source code far enough to be assured that log_info
>> will generated the proper results, but it certainly appears on the
>> surface to be the right option.
>>
>> I also downloaded the latest source tarball (2.0.2.84) and the
>> situation appears to be the same.
>>
>> Jeff


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