Up 'n' Down
Debian Linux rarely needs rebooting. Its rock solid and runs for weeks, months, err you know the score. Debian in its current iteration runs ext3 file system. Ext3 is a Journal File system meaning data loss is minimized and fsck's are redundant, almost.
Debian by default runs file system check after a few months. Any how in the rare event you need to force an fsck, there are a couple of ways to do it.
Create forcefsck file in the root filesystem. You must be root user for this.
# touch /forcefsck
Force a shutdown, fsck and reboot.
# shutdown -Fr now
-F forces fsck on reboot
-r forces a reboot