Safely free some space on rootfs

This script shows you how much space is freed. It can also detect whether some directories have already been moved. WARNING: Although this script works for most users, you should always perform a backup before running it. Do not use this script if you have already used some other methods or scripts from Free_up_rootfs_space! In this case reflashing is recommended.

1. install the rootsh package from extras
2. download the script to your MyDocs (or upload it via SSH)
3. in Terminal run

sudo gainroot
sh /home/user/MyDocs/moveroot.sh

It should have freed about 95MB on your rootfs. Upgrading the firmware OTA after using the script is supposed to work. If you reflash the firmware the script will automatically remove the files from the old firmware when you run it again.
This untested script reverts the modifications and moves as many as possible files back to rootfs. Make sure that you have enough space on rootfs for that. Otherwise it will abort the operation. Instructions are the same as for moveroot.sh, except that you call unmoveroot.sh.

[edit] On-device flashing of a custom kernel image

This how to flash a kernel on-device (without USB/flasher 3.5):

1. you have a kernel image /path/zImage (with it's modules installed)
2. install the package "sdk-fiasco-gen" from SDK
3. become root: "sudo gainroot"
4. make a "fiasco" :)

fiasco-gen -o /path/zImage.fiasco -g -k /path/zImage

1. flash it

/sbin/fiasco-image-update /path/zImage.fiasco 

[edit] Reflashing & Restore

this is a slightly modified version of the script I use to restore my N900 after a reflash. My reflashing procedure is:

1. store all settings with Backup on my SD card
2. reflash with standard http://wiki.maemo.org/Updating_the_firmware, i.e.

sudo flasher-3.5 -F <current firmware image>.bin -f -R

1. restore old backup except programs
2. install rootsh from System
3. in Terminal:

sudo sh /home/backup/restore.sh

with this script (for PR<1.2 or this script (PR1.2) in /home/backup (feedback and patches are welcome). It expects that you made a backup of /root and your selected modified files (e.g. /etc/ssh) in /home/backup. The file "pkgs" should contain a list (line by line) of the package names you want to install.

Credit to   http://wiki.maemo.org/User:Tanner#Safely_free_some_space_on_rootfs