Saturday, October 23, 2010

Customized Ubuntu distributions part two

Turns out I was mostly still spinning my wheels here -- move on to part three of this tale for the solution to the problem.

After a brief visit to the world of Damn Small Linux and subsequent narrow escape from eternal damnation, I returned to Ubuntu with the idea of reducing the size (not as big a priority as I initially thought), speeding up the boot time, and running a program when the user logs into X.

First a quick note about the 9.10/10.04 UCK thing. What's working well for me is to run UCK on a box that has 10.04 installed, and apply it to a 9.10 ISO. Do not attempt to run UCK inside a VMware instance, it's just a lot of pain. You can run the resulting ISO in QEMU but don't forget the "-boot d" argument.

To shrink the distro, I removed OpenOffice, Ubuntu Docs, and Evolution. Things I added included autoconf, emacs, git, guile, and openssh-server.

The low-hanging fruit for speeding up boot time is to bring up networking as a background process, described here. Doing this in Ubuntu 9.10 means editing /etc/init.d/networking, adding "&" here:
case "$1" in
        /lib/init/upstart-job networking start &
People have given a lot of thought to other approaches to speed up Ubuntu's boot time, and maybe I'll blog more about that as I investigate it further. I really need to dig deeper into the boot time topic. It will likely warrant another blog post.

Having an app start immediately when the user logs in is somewhat interesting. The X session startup stuff is all in /etc/X11/Xsession.d/ and the main thing here is /etc/X11/Xsession.d/40x11-common_xsessionrc where we find a call to the user's ".xsessionrc" file. The user's directory is populated from /etc/skel, so the trick here is to create /etc/skel/.xsessionrc:
export LC_ALL=C
${HOME}/ &
where is a sample shell script just to make sure I've got the principle down pat:
sleep 2   # wait for other xinit stuff to finish
xterm -geometry 120x50+0+0 -e "echo HELLO WORLD; sleep 5"

Hmm... that worked for a bit, then stopped working. I've since discovered another file, /etc/gdm/PreSession/Default, which seems more relevant. But that starts the app just a little too early, before the user is actually logged into the X session, so maybe I should put a time delay in my app? Annoying.

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