What command is utilized to fix a filesystem?

The command used to fix a filesystem is 'fsck', which stands for filesystem check. It is designed to check and repair inconsistencies in filesystems. When executed, fsck scans the designated filesystem for errors such as corrupt data, missing files, or structural issues, and attempts to correct these issues.

The operation of fsck is crucial for maintaining the integrity of the filesystem, especially after an improper shutdown or when a filesystem has been marked as dirty. It can often be run from a live environment or during system boot to ensure the filesystem is in a healthy state, thereby preventing potential data loss or further corruption.

In contrast, other options listed serve different purposes. For example, mdadm is used for managing Linux software RAID arrays, while dumpe2fs displays superblock and block group information about an ext2/ext3/ext4 filesystem. The command rune2fs does not exist as a standard command in Linux; it may be a typographical error or confusion with other filesystem-related commands. Understanding the specific functionalities of these commands clarifies why fsck is the appropriate choice for fixing filesystems.