The fsck application is a frontend for filesystem specific fsck applications. When we run fsck, it detects the type of the filesystem and runs the appropriate fsck.fstype command, where fstype is the type of the filesystem. For example, if we run fsck on an ext4 filesystem, it will end up calling the fsck.ext4 command.

Because of this, fsck supports only the common options across all filesystem-specific tools. To find more detailed options, read the application specific man pages such as fsck.ext4.

It's very rare, but possible, for fsck to lose data or make a badly damaged filesystem worse. If you suspect severe corruption of a filesystem, you should use the -N option to list the actions that fsck will perform without actually performing them. If fsck reports more than a dozen problems it can fix or if these include damaged directory structures, you may want to mount the drive in the read-only mode and try to extract critical data before running fsck.