[lttng-dev] lttng create --output problem

[dgoulet@efficios.com (David Goulet)]

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On 12-04-03 04:26 PM, Ettore Del Negro wrote:
> Hello,
> actually 'lttng create --output dir session_name' should at least create an
> empty directory with the chosen name. First of all try not to choose an already
> existing directory so you can check whether it is created or not.

Actually it does. If you type: lttng create test -o /tmp/test

/tmp/test is created and empty.

> 
> Anyway, i just noticed a problem with relative paths:
> (~)> lttng
> LTTng Trace Control 2.0.0-rc2
> (~)> lttng create --output traces session
> Error: Create directory failed
> (~)> lttng create --output ./traces session
> Error: Create directory failed
> (~)> lttng create --output /root/traces session
> Session session created.
> Traces will be written in /root/traces

I've just tested it. The trace output directory, given without a full path, is
created at the $PWD of the session daemon. If the directory exist, it will
simply write the trace in it.

So, the error you have are probably related to a location you don't have write
access.....

I agree that the relative path could be handle better and use the current
directory of the user using "lttng".

Thanks!
David

> 
> Is this expected?
> 
> Regards,
> Ettore
> 
> On 3/4/2012 10:11 PM, David Goulet wrote:
>> Hi Ryan,
>>
>> Well, the --output works on our test suites so it might be something you do that
>> does not create the trace.
>>
>> Simply using create, start and stop will produce nothing. You have to at least
>> enable events for trace files to be created since they are opened by the consumer.
>>
>> Can you try "lttng enable-events -a -k" (enabling all kernel events) after the
>> create session and tell me if it works for you? (or use user space tracing,
>> whatever works for you).
>>
>> If not, add "-vvv" to the lttng command for debug output and also for the
>> session daemon.
>>
>> # lttng-sessiond -vvv
>> # lttng -vvv ...
>>
>> Thanks!
>> David
>>
>> On 12-04-03 04:02 PM, Ryan.Kyser at jci.com <mailto:Ryan.Kyser at jci.com> wrote:
>>
>> > Whenever I try using the --output flag for creating a new session, it doesn't
>> > seem to use the location specified. Additionally, if I do a find on the entire
>> > file system, no files are found that start with session name specified. This
>> > seems like a bug to me ... or am I doing something wrong?
>>
>> > //---------------------------------------
>> > // Log
>> > //---------------------------------------
>>
>> > / # lttng create --output /tmp new3
>> > Session new3 created.
>> > Traces will be written in /tmp
>> > / # lttng start
>> > Tracing started for session new3
>> > / # lttng stop
>> > Tracing stopped for session new3
>> > / # ls /tmp
>> > wayland-0       wayland-0.lock
>>
>>
>> > Thank you,
>> > Ryan Kyser
>>
>>
>>
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>>
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> 
> 
> 
> 
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