How do I control UL via jcmd VM.log?

Staffan Larsen staffan.larsen at
Wed Jan 27 14:18:07 UTC 2016

The documentation clearly needs som work. But “jcmd <pid> help VM.log” gives you some hints.

I think this does what you want (although I’m not completely sure):

$ jcmd <pid> VM.log what=all=trace

> On 27 jan. 2016, at 14:48, Thomas Stüfe <thomas.stuefe at> wrote:
> Hi all,
> sorry if this is a stupid question. I have trouble figuring out the syntax
> to enable Logging dynamically using jcmd for a life process.
> Whatever argument I hand down to the VM.log command, I
> get java.lang.IllegalArgumentException.
> Examples:
> ./images/jdk/bin/jcmd 12680 VM.log  all
> ./images/jdk/bin/jcmd 12680 VM.log  all=trace
> ./images/jdk/bin/jcmd 12680 'VM.log  all=trace'
> ...
> nothing works.
> I also looked through but
> did not find a clear answer beside "Everything that can be specified on the
> command line can also be specified dynamically with Diagnostic Commands."
> which did not help much.
> What am I doing wrong?
> Thanks and Kind Regards, Thomas

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