You want to update your iPhone or iPod touch to a new version of iOS, but you do not want to lose your apps or themes installed on Cydia. Here's a little guide to save the list of applications installed in a text file (restore them after upgrading iOS)
Save your packages
Open Mobile Terminal (available on Cydia)
Enter the command (without quotes): " dpkg-get-selections> installed-apps.txt "
You should now have a text file in " / var / mobile "called" installed-apps.txt "which lists all installed packages. You can now save this file on your computer.
Reinstalling the packages installed
After you re-install your Cydia and Termina, type these commands in Terminal (the file installed-apps.txt must be submitted prior to / var / mobile)