Forcing fsck at next reboot

1. Check /etc/fstab; the last column for the FSes you want to check must not be 0 (requirement not confirmed but does no harm).
2. Ensure that /etc/default/rcS has FSCKFIX set to yes (requirement not confirmed but does no harm).
3. Create a signal file (it will be removed after fscking has finished):
       echo y > /forcefsck
4. Reboot.

echo y > /forcefsck


Alternatively reboot with the shutdown command's -F option. Not all system support the -F option.  For example:

shutdown -rF now