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fsck stands for "file system check" and it is used to check and optionally repair one or more Linux file systems. Normally, the fsck program will try to handle filesystems on different physical disk drives in parallel to reduce the total amount of time needed to check all of the filesystems (see:
The Arch Linux boot process conveniently takes care of the fsck procedure for you and will check all relevant partitions on your drive(s) automatically on every boot. Hence, there is usually no need to resort to the command-line unless necessary.
To check all the relevant partitions immediately, run:
# shutdown -Fr now
The command shutdown brings down the system in a secure manner, -F forces fsck to be safely invoked on a reboot, -r causes the system to reboot after shutdown, and now shuts down the system immediately.
Another method would be to create a
forcefsck file on the partition you wish to check later. For example, for the root partition it would be:
# touch /forcefsck
When you're ready, reboot and fsck will do the rest. And don't worry, this file will be removed automatically when the process is finished.
Other fsck tricks
A list of all available options can be found by running:
# fsck -h
To automatically repair damaged portions, run:
# fsck -a
To make no changes to the filesystem (opposite of the above, meaning the answer is No when asked about fixing errors), run:
# fsck -n
Changing check frequency
By default, fsck checks a filesystem every 30 boots (counted individually for each partition). To change the frequency of checking, run:
# tune2fs -c 20 /dev/sda1
In this example,
20 is the number of boots between two checks.
1 would make it scan at every boot, while
0 would stop scanning altogether.
# dumpe2fs -h /dev/sda1 | grep -i 'mount count'
fstab is a system configuration file and is used to tell the Linux kernel which partitions (file systems) to mount and where on the file system tree.
/etc/fstab entry may look like this:
/dev/sda1 / ext4 defaults 0 1 /dev/sda2 /other ext4 defaults 0 2 /dev/sda3 /win ntfs-3g defaults 0 0
The 6th column (in bold) is the fsck option.
- 0 = Do not check.
- 1 = First file system (partition) to check;
/(root partition) should be set to 1.
- 2 = All other filesystems to be checked.
Can't run fsck on a separate /usr partition
- Make sure you have the required hooks in
/etc/mkinitcpio.confand that you remembered to re-generate your initramfs image after editing this file.
- Make sure that the bootloader has
roon the "APPEND" line in
/boot/syslinux/syslinux.cfg(for Syslinux). GRUB doesn't need one; it is added automatically when you generate a .cfg. For an explanation as to why you need "ro", see this post.
- Check your fstab! Only the root partition needs "1" at the end, everything else should have either "2" or "0". Carefully inspect it for other typos, as well.