Sat, 21 Feb 2009
GDB Pocket Reference - (Very) Short Review
If you already know GDB then this book might
be useful. It's full of command summaries and option listings but
lacks an actual introduction or any walk through examples.
A google for GDB tutorials bought back some well written intros with actual sample code I could work through which is probably a more useful approach for most people.
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Posted: 2009/02/21 12:05 | /books | Permanent link to this entry | This entry and same date
Wed, 04 Feb 2009
Nagios check_http flaps
We recently had an odd one where the Nagios check_http check, which was
both checking for the presence of a string in the response and that the page
loaded in a certain time frame, went from reporting a 'CRITICAL - string
not found' to a 'HTTP WARNING: HTTP/1.1 200 OK'. My first thought, as
this was a site pending migration, was that the URL had moved to a
slower machine with the fixes released to it. Alas, it's seldom that
obvious.
It turns out that somewhere in the Nagios check a slow page that exceeds the -w options threshold overrides the fact that the string is missing, even though that's a warn replacing a crit. Bah.
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Posted: 2009/02/04 16:53 | /sysadmin | Permanent link to this entry | This entry and same date
Tue, 03 Feb 2009
Simple, Single Document Bookmarks in vim
I like vim, I think it's a great editor
worth investing time and effort in to learning but I also think it's one
of the most horrible things to watch an inexperienced user typo his way
through while you're urgently waiting for them to finish the damn edit.
My favourite one this week (and it's only Tuesday) is looking for
probably unique phrases that you can later search for to return to a
specific part of a document.
In an attempt to stop my laptop getting any more back of the head shaped
dents in it from when I've failed to restrain myself I thought I should
point out a much simpler way of doing this. Once you're at the part of a
document you want to return to press m<letter>. This
sets a mark. To return to it press '<letter>. That's it.
No more pasting in chunks of a string hoping it only occurs once in the
damn document. If you need to mark a couple of locations then fine just use
different letters to set and return to the places you want. And save me
sending another laptop back in for warranty.
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Posted: 2009/02/03 22:05 | /tools/commandline | Permanent link to this entry | This entry and same date
Splitting Syslogs by Facility
Logs are a wonderful thing. If done correctly they point out the source of
all errors, show you what's running slow and contain useful information on
how your system is running. At every place I've ever worked they've been
busy, full of odd one offs and too often overlooked.
I'm going to be doing a fair bit of log processing next week so expect lots of little toolchain scripts like syslog-splitter.pl to be checked in to git and mentioned here.
syslog-splitter takes a logfile as an argument and breaks the logfiles
in to many smaller units, one file per facility (which contains all the
lines for that facility from the logfile), to make it easier to process. I
seem to invoke it followed by wc -l out/* | sort -nr when on
new machines to work out where I need to invest some time. Over the next
week or so I'll come back to the topic and show how I'm reducing the noise
to help me find the important lines.
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Posted: 2009/02/03 21:49 | /sysadmin | Permanent link to this entry | This entry and same date
Copyright © 2000-2010 Dean Wilson
