Using multiple keys for github

Recently, I was working from my office laptop. I had set up ssh keys for Github on that system. However, when I had to work from my personal system, I realized that I don't have those ssh keys with me on this system. Also, the ssh keys on the current system were used for another purpose. So, I decided to have multiple keys on Github as well as on my system. I created my new keys with the following command:

ssh-keygen -t <rsa/dsa as per your choice> -f <new private key file like ~/.ssh/id_dsa.github> -C "comment"

This created a new key pair for me. Now, I had to configure ssh to use this key for github. So, I added the following lines to ~/.ssh/config file.

Host github.com
IdentityFile ~/.ssh/id_dsa.github
User git

Now, I had to add this new key to my ssh keys on Github. I opened the new public key file (id_dsa.github.pub in the above case) and copied its contents to add a new key on Github. I tried ssh -vT git@github.com and verified that it was using the new key and I was able to access Github successfully.

OpenSSH_5.9p1, OpenSSL 1.0.0g 18 Jan 2012
debug1: Reading configuration data /home/me/.ssh/config
debug1: /home/me/.ssh/config line 9: Applying options for github.com
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Connecting to github.com [207.97.227.239] port 22.
debug1: Connection established.
debug1: identity file /home/me/.ssh/id_dsa.github type 1
debug1: identity file /home/me/.ssh/id_dsa.github-cert type -1

AlpsPS/2 ALPS DualPoint TouchPad on Arch linux

In my new Dell Latitude, there is an AlpsPS/2 ALPS DualPoint touchpad. When I installed Arch linux on it the touchpad worked fine for me. I do not use the touchpad button and prefer to tap on the touchpad for a click. This feature worked fine with the initial configuration. However, after a system update which included a kernel update too, tap did not work.

I had not gotten into details of the touchpad before this incident. When I found it was not a Synaptics touchpad, I got scared that I might not get a decent linux driver for it. Just about a month ago I was looking for a decent driver that supports Nvidia Optimus tecnology; but all my efforts were in vain.

As I started looking for a driver for my touchpad, I found out that the synaptics driver is not only for synaptics touchpads. So, I installed xf86-input-synaptics package. Tap for click started working as the default /etc/X11/xorg.conf.d/10-synaptics.conf has the configuration for tap.

        Option "TapButton1" "1"
        Option "TapButton2" "2"
        Option "TapButton3" "3"

Also, two finger scroll started working. I had no idea that my touchpad supports it. The freedesktop.org documentation however specifies a config for Alps touchpads. I read through synaptics configuration on Arch wiki to configure the touchpad to suit my usage. The Gentoo wiki also provides a number of configurations, in case you want to try things out. The AccelFactor value mentioned in these wikis turns out to be too slow for me. So, I increased its value. 

Customizing system-wide gem install

I hardly use gem documentation and mostly install with --no-ri and --no-rdoc options. So instead of typing these options each time I install a new gem, I decided to apply these by default. Adding the following to /etc/gemrc achieved it.

gem: --no-ri --no-rdoc