When I want to change the mirror I am using for updates, I can open the Software Centre, and go to Edit->Software Sources, and from there select another server.
This then goes through my /etc/apt/sources.list file, and replaces all the instances of the old mirror URL, with the new mirror URL.
If, however, I want to do this on the command line (perhaps I'm not running X, or I'm connecting over ssh), I have to go through the /etc/apt/sources.list file myself and change each instance.
This isn't the hardest thing to do, and of course I can do a search and replace, but it is a lot more work than just clicking the name of the server I want, plus it requires me to know a bit about the syntax of the sources.list file, and make sure I don't make an error while editing it.
Is there a command line program which can perform the same task as the Software Centre, and change my update mirror, without me having to edit this file?
sed
to replace the server with another with a "s/oldserver/newserver/"