Well... After Flashing, I still have my wifi codes in /home/user, but they are no more used when connecting to wifi spots.
I have to enter the again as if they were no more available.
This is a different matter, which does not cancel my question.
Codes are hidden in a deep repertory, and difficult to extract. A good idea should be to make a script to put all the codes in a singe file to make them easy to copy/paste.
Another reason to make some automatic script is the codes are often complex, and the n900s keyboard is not the best keyboard ever.
Another reason is, computers are supposed to make things an automatic way. My codes are stored in the computer. There should be a way to use them again.
And I have no time to find the code, type it at the moment when I need it.
Restoring an old backup might work, I would worry it might overwrite some new settings/data with old ones though.
And you don't have to type the keys in if you have them saved in a file, you can open that file and copy and paste (using Ctrl-v to paste) them, you can also go into Settings - Internet Connections, and create connections for each network you use, if you don't want to create them as you need them.