[rancid] FW: routers router config diffs

Chris Moody chris at siliconhotrod.com
Thu Apr 28 01:08:55 UTC 2011

<NOTICE - anyone on the list that does not approve of customizations, 
PLEASE pardon what I'm about to say.  I'm simply trying to offer a hand>


Yes - I have run into behaviors like this for our Nexus deployments.  I 
was even seeing some log file for the CPM module (with 0 bytesize) 
getting "touch"ed by the OS periodically...making it show up as 
something new/different.  Annoying is putting it kindly.  Particularly 
when you cannot control the behavior....but I digress.

What we (I) did to rectify the problem was to add some "exclusions" into 
the nxrancid routine. (not sure if you're using cisco or cisco-nx device 
types).  It involves some -very- simple programming to modify the code 
to suit your needs.  I'm writing this assuming little programming skills 
on your part for the sake of assumption.  If you're more 1337, then 
pardon my simplification.

Copy the original executable to something like nxrancid-ORIG so that you 
have a working backup BEFORE making any changes.  Fire up 'vi' and you 
scroll down through the code to the stanza that's running the command(s) 
that are triggering the output.  For the sake of this discussion, let's 
say it's the 'DirSlotN' subroutine that's running the command 'dir 
logflash' which is causing this output.  Find the subroutine 'DirSlotN' 
and then you'll need to insert a command before the 'ProcessHistory' 
line that will cause the routine to skip over the output line(s) that 
are causing you a problem.

scroll down to here...
# This routine parses "dir /all ((disk|slot)N|bootflash|nvram):"
sub DirSlotN {
     print STDERR "    In DirSlotN: $_" if ($debug);

     my($dev) = (/\s([^\s]+):/);

     while (<INPUT>) {
===<output truncated>===
after these lines... but before this line...

ProcessHistory("FLASH","","","!Flash: $dev: $_");

You should find some space just before the ProcessHistory line.

So,  for your particular issue, you'd insert a perl code statement like so:

/syslog\/log_20/ && next;

What this accomplishes is, via regex, any line that pattern matches 
'syslog/log_20' will get jumped over and ignored.

I know this is a hack, but it's what solved our issues.  Just be SURE to 
save a copy of the modifications & note someplace that this has been 
modified or you will run into trouble if/when you upgrade and it gets 

If you need help with any specifics, please feel free to shoot me an 
email off-list (so as not to spam people with customizations)


On 4/27/11 3:17 PM, Chris Gauthier wrote:
> Anyone seen this issue with rancid and Cisco IOS 15.0?  I tried to find out which version of rancid I have, but I cannot seem to find it.  Anyway, here is the behavior and it is really annoying since the only change is that file.  This seems a lot like the earlier ASA "crashdump" issue that they had.  I don't want to see these all the time.
> Thanks,
> Chris
>   Index: configs/
>   ============================================================= ======
> retrieving revision 1.15
> diff -U 4 -r1.15
> @@ -26,11 +26,11 @@
>    !Flash: 9            0 Nov 05 2010 00:07:16 syslog
>    !Flash: 11        6523 Nov 05 2010 00:11:44 startup-config-20101104_1711
>    !Flash: 12      261987 Apr 20 2011 06:12:00 syslog/log_20110416-121956
>    !Flash: 13      258273 Apr 25 2011 00:01:08 syslog/log_20110420-001701
> - !Flash: 14      120840 Apr 27 2011 17:41:12 syslog/log_20110424-202035
> + !Flash: 14      124993 Apr 27 2011 19:01:12 syslog/log_20110424-202035
>    !Flash: 16      258002 Apr 16 2011 17:40:18 syslog/log_20110413-001319
> - !Flash: 221515776 bytes available (36225024 bytes used)
> + !Flash: 221511680 bytes available (36229120 bytes used)
>    !
>>    !Flash: nvram: Directory of nvram:/
>>    !Flash: nvram:   244  -rw-        6605<no date>   startup-config
>>    !Flash: nvram:   245  ----        3573<no date>   private-config
> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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