Linux

To monitor Tomcat with Munin 2.0 on Debian GNU/Linux (tested on Debian Squeeze with Tomcat6 and Debian Backports), you need the following steps.

First, you need to install package tomcat6-admin which enables the Tomcat Manager app we will be using.

# apt-get install tomcat6-admin

Next, create a user with a manager role in Tomcat, editing /etc/tomcat6/tomcat-users.xml and adding the following two lines in the appropriate list.

Why re-invent the wheel? This post gives ample details: http://www.cyberciti.biz/faq/find-linux-distribution-name-version-number/ cat /etc/*-release o lsb_release -a

The documentation to install BigBlueButton 0.64 on CentOS (and on most other distributions) is really excellent. However, I found that CentOS 5.5 had not been documented yet, so I tried it and run into a few problems. I explain below how to get it all sorted out. I installed CentOS5.5 from a DVD in "server" mode, so without graphical interface.

Disclaimer: this article does not pretend to be a complete picture of using swap on UNIX. Most of the time, recent GNU/Linux distributions insist on creating a swap area. Swap is generally used to temporarily store memory used by running(/sleeping) applications, but might as well be used to store a copy of RAM to disk for hibernation.

GNU/Linux supports swapping to a file on any filesystem, with reasonable performance impact since kernel 2.4.

I had a problem with a very old Compaq PC not detecting the keyboard anymore. I used the PC as a local server, not a real problem, except that the BIOS didn't allow the PC to boot when the keyboard was not plugged in. One solution there might have been to use some USB keyboard (I didn't get a chance to try that - didn't have any USB keyboard lying around). Luckily enough, I happened to have a clone of this computer, so I just swapped the disks from one PC to the other, and booted.

I can't resist posting a link to this blog post :-)  Takes around 1 minute to read it all... Great effort from the author. Comparative installation of simple cards game under Ubuntu and under Windows.

On Linux systems, there used to be a mildly complicated but tedious way to allow you to SSH another computer using your public key, which involved finding and copying your public key on the other host, then connecting to the host and putting this key into ~/.ssh/authorized_keys. Now there is a much simpler way to do that... Just launch the following command (with your own data), enter your password, and that's it!

ssh-copy-id  yourusername@remote.host.address

I love administrative simplification!