In our earlier discussion of the /etc/fstab file, we saw some mysterious digits at the end of each line. Each time the system boots, it routinely checks the integrity of the filesystems before mounting them. This is done by the
fsck program (short for filesystem check). The last number in each fstab entry specifies the order in which the devices are to be checked. In our example above, we see that the root filesystem is checked first, followed by the home and boot filesystems. Devices with a zero as the last digit are not routinely checked.
In addition to checking the integrity of filesystems,
fsck can also repair corrupt filesystems with varying degrees of success, depending on the amount of damage. On Unix-like ...