[Xymon] Issue with Regex and NORRDDISKS Setting

[J.C. Cleaver]

Hmm. Taking a look at the code, there's not really a provision for
escaping in this manner. And unfortunately, this is parsed in various
places throughout xymonlaunch (and passed onto the shell).

The only workaround that seems to work properly is substitution prior to
xymoncmd's reading:

in xymonserver.cfg:
NORRDDISKS='^(/dev|/tmp|/var)$FOO'

then run:
env FOO='$' xymoncmd env | grep NORRD


You could either place FOO='$' in a shell wrapper launched from tasks.cfg,
or stick it way up in /etc/sysconfig/xymonlaunch (if you're using the
RPM).

I'm tempted to try a patch allowing '$$' to mean an unprocessed '$', but
that might interfere with people who want a shell PID for some reason.
Alternatively, adding '\' escaping globally in environment files might
cause other sorts of problems for folks.


Alternatively-alternatively, NORRDDISKS='^(/dev|/tmp|/var)\Z' might work
for you, since this *is* just straight PCRE...


-jc


On Wed, March 2, 2016 11:23 am, Matt Vander Werf wrote:
> Hi J.C.,
>
> It doesn't seem to be working with or without the escape backslash. It
> doesn't show up in the env output either way.
>
> root@<host> ~]# grep NORRDDISK /etc/xymon/xymonserver.cfg
> NORRDDISKS="^/dev|^/var|^/tmp$"
> [root@<host> ~]# xymoncmd env | grep NORRD
> 2016-03-02 14:18:47.151545 xgetenv: Cannot find value for variable
> NORRDDISKS=^/dev|^/var|^/tmp
>
> [root@<host> ~]# grep NORRDDISK /etc/xymon/xymonserver.cfg
> NORRDDISKS="^/dev|^/var|^/tmp\$"
> [root@<host> ~]# xymoncmd env | grep NORRD
> 2016-03-02 14:17:47.233910 xgetenv: Cannot find value for variable
> NORRDDISKS=^/dev|^/var|^/tmp
>
>
> When I do it with them grouped together, it gives me the same result:
>
> [root@<host> ~]# grep NORRDDISK /etc/xymon/xymonserver.cfg
> NORRDDISKS="^(/dev|/var|/tmp)$"
> [root@<host> ~]# xymoncmd env | grep NORRD
> 2016-03-02 14:20:35.984507 xgetenv: Cannot find value for variable
> NORRDDISKS=^(/dev|/var|/tmp)
>
> Any ideas?
>
> Thanks!!
>
> --
> Matt Vander Werf
>
> On Wed, Mar 2, 2016 at 11:50 AM, J.C. Cleaver <cleaver at terabithia.org>
> wrote:
>
>>
>>
>> On Wed, March 2, 2016 8:31 am, Matt Vander Werf wrote:
>> > Hello,
>> >
>> > Looking at past list e-mails, it is my understanding that the
>> NORRDDISKS
>> > setting in xymonserver.cfg allows for PCRE regular expressions. Is
>> this
>> > correct? Or does it only allow certain PCRE regular expressions, but
>> not
>> > everything?
>> >
>> > I ask because I'm experiencing an issue with my NORRDDISKS setting.
>> >
>> > I'd like to ignore disks for graphing that have mount points "/tmp",
>> but
>> > not ignore disks with mount points that have "tmp" in them, like
>> > "/tmpscratch".
>> >
>> > I noticed that for other disk mount point names that if you just use
>> > "^/<name>" with no modifiers, then it only ignores disk mount points
>> with
>> > only exactly "^/<name>" and not "^/<name><additional text>" or
>> > "^/<name>/<more name>" (at least from what I can tell).
>> >
>> > For example when using:
>> >
>> > NORRDDISKS="^/dev|^/tmp|^/var"
>> >
>> > It ignores disks with mount points "/dev" and "/var", but also "/tmp"
>> AND
>> > "/tmpscratch". But it doesn't look like it ignores "/var/tmp" (at
>> least
>> as
>> > far as I can tell).
>> >
>> > I tried using "^/tmp$" and that didn't work either (still ignored both
>> > names).
>> >
>> >
>> > Any idea what's going on here? Or how this can be done correctly? Is
>> the
>> > "$" metacharacter not allowed in this setting?
>> >
>> >
>> > If it's needed, I'm running the latest 4.3.26-1 Terabithia RPM on RHEL
>> 7.
>> >
>> > Thanks for any help!!
>> >
>> > --
>> > Matt Vander Werf
>>
>>
>> Try checking the output of 'xymoncmd env | grep NORRD' ? If the '$' is
>> not
>> coming through, it might be getting read in as an attempt at a shell
>> variable.
>>
>> If so, can you try escaping it as \$ instead?
>>
>> Alternatively: '^(/dev|/tmp|/var)$'
>>
>>
>> HTH,
>> -jc
>>
>>
>