My PC restart about 6 to 7 times a days because of electricity fluctuate.
So I want to ask: do I have to run fsck
/tune2fs
tools to check my file system at every restart or do you recommend something else?
To check the filesystem whenever it is mounted:
sudo tune2fs -c 1 /dev/<device>
The system automatically checks the filesystem whenever it is marked dirty, however in case of power failures or similar events the filesystem could get corrupted without being marked dirty. So yes, checking the filesystem at every reboot is a good thing to do in your case (actually, the best thing to do would be to fix the electricity problem, but I suppose you are already aware of that :-))
If you can't control the power fluctuations to your home/office, you can at least control whether your computer is affected by plugging it into, basically, a big battery - > http://en.wikipedia.org/wiki/Uninterruptible_power_supply It can either automatically (gracefully) shut down your computer or give you a few minutes to manually shut it down. Maybe you just need a few minutes between fluctuations and this would even allow you to continue working without interruption? Good luck.