[Xymon] Xymon on Mac OS X: Time Machine volumes; stopping after IGNORE

[Jeremy Laidman]

On 8 May 2014 08:10, Greg Earle <earle at isolar.dyndns.org> wrote:

> My RE smack-fu must be sorely lacking in my old age, because this isn't
> working (in analysis.cfg):
>
> HOST=macmini
>         INODE %^*.Time.Machine.Backups IGNORE
>         DISK %^*.Time.Machine.Backups 98 99
>         PROC    "/opt/tripwire/te/agent/jre/bin/java" IGNORE STOP
>

Firstly, you probably want ".*" instead of "*.".  The "*" means "zero or
more of the last character", so ".*" means "zero or more of any character".
 That's basic RE that you need to know.

If you want to exactly match "/Volumes/Time Machine Backups" then you
shouldn't need to use a regular expression at all, and just put the
filesystem name in quotes (to allow spaces in the filesystem name):

DISK "/Volumes/Time Machine Backups" 98 99

Unfortunately, that doesn't work.  The parser does the right thing, but the
filesystem matching code matches against the part of the filesystem name up
to the first space.  (Interestingly, "xymond_client --test" matches
correctly.)  So this would match your "Time Machine Backups" volume:

DISK /Volumes/Time 98 99

But this would also match other filesystem names starting with "Time" when
followed by a space, like "/Volumes/Time Magazine Photos".  You probably
don't want that.  From what I can tell, a regular expression is the only
way to match filesystem names containing spaces.

If you want to match any volume mounted in a folder called "Time Machine
backups", and mounted anywhere on the filesystem, then you don't need to
anchor to the start with "^".  Instead, you really want to anchor it to the
end.  You want to match (for example) "/any/where/Time Machine Backups" but
not "/some/place/Time Machine Backups Copy", nor "/other/place/Copy of Time
Machine Backups".

So:

DISK "%/Time Machine Backups$" 98 99

So this matches if the end of the mount point has a slash then the string
"Time Machine Backups".  Because it's in quotes, the spaces will be
included in the regular expression.  This is what I'd do.

If you wanted to leave out the quotes for some reason, you could replace
the spaces with dots:

DISK %/Time.Machine.Backups$ 98 99

but that would also match "/Volumes/TimerMachine-Backups", which isn't
strictly correct for your use-case, but will probably always do what you
want anyway.

A more correct way to match a whitespace character using "\s", like so:

DISK %/Time\sMachine\sBackups$ 98 99

Technically, this is also not correct because it matches tabs also.  But
you can use an escaped octal or hex character to specify a space:

DISK %/Time\040Machine\040Backups$ 98 99

This is almost certainly more than you wanted to know about the subject.
 But I hope that at least you'll understand why your attempt didn't work.

Cheers
Jeremy
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.xymon.com/pipermail/xymon/attachments/20140508/e8471b46/attachment.html>