Mindless Techie » Tips and Tricks

Installing RubyGems on Centos 5

John Alberts — Tue, 27 Oct 2009 18:37:47 +0000

This should apply to RHEL5 as well, but I haven’t verified yet.

The easiest solution I’ve found is to simply install Ruby and it’s dependencies and then install RubyGems from source.

I’ve written a small script which installs Ruby and it’s dependencies. It then grabs the RubyGems source tarball and installs Gems from source. As I wrote this to get a working Chef install, it also adds an opscode gems source.

You can get the script here.

Changing the from field when sending email

John Alberts — Thu, 10 Sep 2009 15:40:53 +0000

This is simple, but I always forget how to do it when I need it and it’s hard to find on google for some reason.

echo "hi" | mail -s "My Subject" to@someone.com -- -f from@someone.com

Dress-up your Firefox

John Alberts — Mon, 07 Sep 2009 23:54:01 +0000

I just stumbled across a Mozilla Labs project called Personas. It’s light-weight theming for Firefox that can be changed without restarting the browser. After you install Personas, you get a new menu entry Tools->Personas for Firefox, where you can quickly change the persona you are using. From what I can tell, Personas seem to change the your browser toolbar and menu font colors and usually add a lightweight background picture. According to the website, the project has been going since Dec 2007, so there’s a lot of Personas to choose from. I guess I’m a little slow sometimes.

One thing that is really cool is you can visit the personas gallery and see a bunch of different personas and when you hover your cursor over a persona, your browser will temporarily use that persona. If you want to use that persona now, just click on it and it’s your active persona.

Here’s a quick little clip that shows what Personas does.

Capture your screen in seconds

Combine your partition space with mhddfs.

John Alberts — Mon, 19 Jan 2009 23:55:10 +0000

As I was browsing the Gentoo forums today, I came across a very interesting post.

A user had 2 partitions on different hard drives that he wanted to combine the space on. Ok, well the interesting part was one persons reply about a new fuse filesystem called mhddfs. He pointed out an article on debian.net that explained a bit about this new filesystem and how to use it.

Sure, there’s multiple ways to combine the two drives, but this one is pretty intesting. You can use mhddfs to combine 2 partitions into one virtual partition. Mhddfs will automatically merge (overlay) the contents of both partitions so it looks like one big partition.

The advantages are:

No need to move and backup existing data on the partitions.
Easily implemented in fuse.
Allows a regular user to mount and unmount the filesystem.

According to the forum thread poster, his tests show there is virtually no speed difference when using mhddfs, which is very surprising. My experience with using fuse in the past with NTFS, was that it was painfully slow. I’m sure things have matured greatly since I tried it a few years ago.

Conky now supports MOC player

John Alberts — Tue, 13 Jan 2009 04:46:34 +0000

So, I found myself tweaking my Conky rc file today. I’ve been using mocp for playing music becuase it’s a really lightweight, versatile and can run detached from the console. I really wanted to see my currently playing music info on my desktop in Conky, but Conky’s documentation shows no mention of any support for moc and thier are no mention of variables to use for the config.

So, in doing some googling, I found a website that has a patch for moc support and also mentions that it’s been in Conky since September 28th! I guess they haven’t updated the documentation yet.

Here’s a list of the new variables you can use in your conkyrc file to add moc support.

$moc_state: Current state of MOC; playing, stopped etc.
$moc_file: File name of the current MOC song.
$moc_title: Title of the current MOC song.
$moc_artist: Artist of the current MOC song.
$moc_song: The current song name being played in MOC.
$moc_album: Album of the current MOC song.
$moc_totaltime: Total length of the current MOC song.
$moc_timeleft: Time left in the current MOC song
$moc_curtime: Current time of the current MOC song.
$moc_bitrate: Bitrate in the current MOC song.
$moc_rate: Rate of the current MOC song.

Huge List of Tips and Tricks

John Alberts — Fri, 09 Jan 2009 04:55:30 +0000

I can’t believe I never saw this before. Sourceforge has an absolutely HUGE list of tips and tricks. There’s hundreds of Linux tips and lots of programming tips as well.

Using CPAN Unattended

John Alberts — Sat, 03 Jan 2009 03:40:10 +0000

CPAN is great for easily installing and updating Perl modules. I use it all of the time on my servers. It’s a lot easier than managing Perl modules through the systems package manager. The problem is, when you want to install or update a Perl module, it asks you if you want to follow and install all of the dependencies and the dependencies for that… and so on. Sometimes you want to be anal and make sure it doesn’t install any extra crap, but quite often, it would be nice to just have it install what it needs automatically, so you can walk away and do other things while it’s installing.
I found this nice little blog post that shows you how to have CPAN automatically install all of the dependencies without prompting you.

Quick and Dirty Linux Load Testing

John Alberts — Wed, 31 Dec 2008 23:48:09 +0000

Today I had a need to keep the load on a server at 20 for an extended period of time. I was doing this to test notification escalations in Nagios. So, I found a nice little program call cpuburn-in that will load a processor at 100%. It’s just a tarball with an executable and a single README file included. To run the program, call the executable and supply the number of minutes you want it to run. So, to run it for 60 minutes, just use:

^?View Code BASH

./cpuburn-in 60

Since I wanted to generate a 20 load on the server for 60 minutes, I just put this in a loop and spawned 20 processes.

^?View Code BASH

i=1; while [ $i -le 20 ];do ./cpuburn-in 60 & i=$(( $i + 1 ));done

This worked nicely for keeping the load right around 20 for me. If you want to kill things off early, just do the following:

^?View Code BASH

ps a | grep cpuburn-in | awk '{print $1}' | xargs kill

Quickly get up to 5% more disk space from your ext3 volumes

John Alberts — Tue, 23 Dec 2008 18:30:37 +0000

I’ve seen many websites that have pretty much the same ext3 performance tips, but I just came across this one today that had something very useful on it.

It turns out that the ext3 filesystem by default reserves 5% of the disk space of the volume just in case the volume fills up. This would allow the system to continue running and allow the root user to still log in and clean things up. The problem is, 5% of a 300G drive is 15G, which is pretty excessive. Like most things, this setting can be changed uisng the tune2fs program. I changed my percentage of reserved blocks to 1% instead of 5% which freed up 10G on my drive.

This was very easy to do with the following:

^?View Code BASH

# tune2fs -m 1 /dev/sda1

Cheat Sheets for Front-end Web Developers

John Alberts — Wed, 09 Jul 2008 00:01:48 +0000

In this article, you’ll find 23 excellent, print-ready cheat sheets for HTML/HTML, CSS, and JavaScript (including MooTools and jQuery).

read more | digg story