Posts Tagged ‘ system ’

Fixing CentOS Root Certificate Authority Issues

Wednesday, June 1st, 2011

While trying to clone a repository from Github the other day on one of my EC2 servers and I ran into an SSL verification issue. As it turns out, Github renewed their SSL certificate (as people who are responsible about their web presence do when their certificate is about to expire). As a result, I couldn’t git clone over https. This presents a problem since all my deploys work using git clone over https.
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Sharing a Screen Session

Friday, July 23rd, 2010

Anyone who has spent any time in a shell and has been cut off while working should know about screen. If not, then I recommend reading up on it (here or here). But I’m not here to tell you about screen as a general tool, I want to show you how to use it for screen sharing. I found a couple of forum posts and other scattered information, so here’s a little centralizing of information.
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Creating Configuration Files With Ruby Templates

Wednesday, June 30th, 2010

I recently had a very repetitive configuration file that needed creating. There were approximately 50 config blocks of 10 lines each with only the host name changing with each block. So I decided to take a shortcut and do it in Ruby using ERB templates. This is so easy and literally save me hours worth of work.
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Nagios notify-by-campfire Plugin

Thursday, May 6th, 2010

Since one of the core communication methods for my company amongst engineers is 37Signals Campfire and Nagios is one of our main monitoring tools for all of our applications and services, I thought it would be a good idea to combine the two. So with a few simple additions to the Nagios configuration and a Ruby Campfire script, you can get this up and running.
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Creating Dummy Packages On Debian

Tuesday, May 4th, 2010

One of my favorite things about Debian is its awesome package management system. Apt is one of the reasons I have used Debian for servers for so many years and eased my initial transition to Ubuntu (which as most people know was initially a Debian fork). Apt is a great tool as long as you aren’t building packages from source (and not making debs out of them). I have packaged a whole bunch of debs, but sometimes it just isn’t necessary. So if you haven’t used equivs, then you need to check it out.
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Monitoring Services with Nagios::Plugin

Wednesday, April 7th, 2010

There are a lot of people who say, “if it isn’t monitored, then it isn’t a service.” The problem is that I don’t think enough people outside of the systems world believe that or even understand why its said. I think the primary offenders here are developers. It isn’t because they don’t know better, but typically developers just want to get the application up and running and then move on to developing the next thing. I also think there is some fault on the side of the administrators and the managers not insisting that part of the completed version of a project includes monitoring. But I don’t want to harp on this as much as I would like to show just how easy it is to compensate here by taking advantage of Nagios::Plugin.
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Cluster SSH with cSSHx

Monday, March 29th, 2010

I am in the middle of building out a group of about 25 machines in a data center for my company. I hadn’t really dove into it on a micro level until a few days ago. I was moving around on individual machines that others were working on. When I had gotten to one of the “untouched” machines, I found that vim wasn’t installed. There was about 15 machines that were “untouched” and therefore were missing vim (along with other stuff). And seriously who wants to install a bunch of the same software on every machine after they’ve already been kickstarted?
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Setting Up daemontools on CentOS 5

Friday, March 26th, 2010

I recently had to setup daemontools on a CentOS system. I had set it up before but it had been a while. So I Google’d around and found very little and what little I did find wasn’t very helpful. So here is a quick and dirty on setting up daemontools. I even included the CentOS fix that I came across to make it compile. There is also a patch version (if you were building an RPM), but I prefer just making the change in this case; it’s much simpler.
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HOWTO Recreate /dev/null

Wednesday, May 27th, 2009

If something happens that requires you to recreate /dev/null on your *nix system. Don’t fret, it’s easy. The most recent issue I had was that a Capistrano recipe inadvertently clobbered /dev/null. The file looked like this:

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[root@web1 ~]# ls -l /dev/null
-rw-r--r-- 1 capistrano engineering 0 May 26 04:02 /dev/null

Thankfully to bring it back to its original state, just run the following commands:

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[root@web1 ~]# rm /dev/null
rm: remove regular empty file `/dev/null'? yes
[root@web1 ~]# mknod /dev/null c 1 3
[root@web1 ~]# chmod 666 /dev/null
[root@web1 ~]# ls -l /dev/null
crw-rw-rw- 1 root root 1, 3 May 26 15:09 /dev/null

Take note of the following things:

  • It is not a joke that the mode of /dev/null needs to be 666. It should be user, group, and world read and write.
  • The user and group ownership here is root.
  • There is no size in the ls like you see in the top one. All you should see are the major (1) and minor (3) device numbers (separated by a comma) prior to the date.