But sometimes I want to be able to pull from upstream, so I want to reactivate the original sources.list. Up to now, I’ve been having to do an awkward dance that involves renaming our file, copying the old default to the active, and then doing the reverse when I’m done.

(As an aside, yum-based systems like Centos or Fedora make this easy. You can say enable=0 in the list file, and then use --enablerepo=myrepo on the command line. There doesn’t seem to be a way to do this with apt, but the command below is almost as good.)

To avoid this renaming dance, here’s a better solution.

First, create a directory to put the original sources.list: /etc/apt/sources.list.ubuntu.

Then copy the original default sources.list into that directory. I called it /etc/apt/sources.list.ubuntu/jaunty.list.

When you want to pull from upstream, run:

apt-get -o Dir::Etc::SourceParts=/etc/apt/sources.list.ubuntu update
apt-get -o Dir::Etc::SourceParts=/etc/apt/sources.list.ubuntu install some-new-package

Then you’ll want to run apt-get update to reset your repository list back to the trimmed-down set.

So I wrote a little script (or a template for scripts) that runs the sudo job in the background (but preserves stdout/stderr) and relies on bash to clean up the job when you ^C the script. Only gotcha with this is that you may have to retype your sudo password when you ^C if your authentication has timed out by the time you get around to killing it.

#!/bin/bash

function cleanup()
{
    sudo kill $job_pid
    wait $job_pid
    exit 0
}

trap cleanup SIGTERM
trap cleanup SIGINT

sudo long_running_foreground_process &
job_pid=$!
wait

http://maps.google.com/maps?f=d&saddr=Elm+St,+ Manchester,+NH+03101&daddr=%s&output=html

[Formatted here for readability. Put it all on one line with no spaces.]

Edit the properties so that the “saddr=” part is your start address. Change the keyword to “gm”. This is set to only output simple HTML (no map). If you want the full map, remove the &output=html on the end.

Now, when you need to get a quick idea of how long it is going to take you to get somewhere, open a new tab and type “gm city, state”.