What command would you use to check the integrity of a filesystem?

The command used to check the integrity of a filesystem is 'fsck' (File System Check). This tool is essential in Linux and UNIX-like operating systems for verifying the consistency of a filesystem. When invoked, 'fsck' scans the filesystem for any possible inconsistencies or corruption and attempts to repair any issues it finds. It can handle different filesystems, including ext2, ext3, ext4, and others. Running 'fsck' is typically done in maintenance modes or when the filesystem is unmounted to prevent data loss.

This command is also often automatable during system boot or scheduled maintenance to maintain filesystem health, making it a critical utility for system administrators. The other options listed do not represent standard commands found in Linux for filesystem integrity checking, which reinforces why 'fsck' is the appropriate choice for this task.