The FSCK (file system check) command checks a file system for errors. 

Important! You need to unmount the filesystem before checking filesystem for errors. You cannot unmount the / (root) filesystem.

In this example, the /dev/sda2 partition is unmounted, then checked for errors, and then remounted. If fsck is able to locate corrupted files, the files will be placed in the /lost+found directory.

~]# umount /dev/sda2
~]# fsck -C /dev/sda2
~]# mount /dev/sda2

Full scan

By default, fsck will do a quick scan. Using the -f (full) option makes fsck run a full scan.

~]# umount /dev/sda2
~]# fsck -f /dev/sda2
~]# mount /dev/sda2

Check file systems in /etc/fstab

The -A option can be used to check every filesystem in /etc/fstab that has a 1 or 2 in the sixth field, such as: /dev/sda2  /home  ext4  defaults  0  1. The -R option skips the / (root) filesystem, just in case the / (root) filesystem has read/write.

~]# umount /dev/sda2
~]# fsck -AR
~]# mount /dev/sda2

Disable interactive prompt

By default, fsck has an interactive prompt, where you will be asked to press Y to fix an issue or N to ignore an issue. The -a or -y options can be used to disable the interactive prompt. This is useful when writing shell scripts.

~]# umount /dev/sda2
~]# fsck -y /dev/sda2
~]# mount /dev/sda2