This is the page for howtos, faqs and documentation about migration from a major linux distribution to Debian.
Back up the data, /etc directory, and so on from the other Linux distro install to be able to migrate all the settings to Debian pretty easily. Get it up and running in a day (or very likely less).
Switching from Red Hat to Debian
If you're switching from Red Hat (or Fedora) to Debian or just administering systems from both distributions, you may find yourself scratching your head over the differences in config file locations and commands, so here's a list to help out.
SysV services
While you could directly call
/etc/init.d/<name> [start||stop||restart||reload]
in Debian or Red Hat, the right way (tm) would be to use the service command in Red Hat, and the invoke-rc.d command in Debian. The syntax is generally the same. Eg.
service apache reload invoke-rc.d apache reload
Since the syntax is the same, you could alias the command one way or the other for root on one of the systems so that it would appear to have the other system's command.
Network Settings
In Red Hat, to edit network settings you mess with ifcfg-<interface> scripts and other files in:
/etc/sysconf/* (especially /etc/sysconf/network-scripts)
In Debian all of the interfaces are handled with a different syntax than the RH syntax in
/etc/network/interfaces
Once you read about the syntax you should find it fairly easy and flexible, allowing you to add custom static routes that are added when the interface goes up and deleted when the interface goes down as well as the simple autoconfigure dhcp options.
Live migration
In an extremely evil, unmaintained, unsupported, broken, do not try it kind of way, you can switch from other Linux distros to Debian using debtakeover: