Which command is used to repair an ext* filesystem?

The command used to repair an ext* filesystem is designated as "fsck," which stands for "file system consistency check." This utility is specifically designed for checking and repairing inconsistencies in various types of file systems, including ext2, ext3, and ext4, which are commonly used in Linux environments.

When the fsck command is executed, it scans the specified file system for issues such as corrupted inodes, blocks, and other structural errors, then attempts to rectify any problems it encounters. Users usually run this command when the system detects an error upon booting or when an administrator believes there could be corruption that needs addressing.

The utility is capable of running in different modes, allowing for repairs and checks of either mounted or unmounted file systems, although it's generally advisable to run fsck on unmounted partitions to prevent data loss or corruption.

In contrast, the other options listed do not exist as standard commands in Linux systems for repairing file systems, making them unsuitable for this purpose. No utility with the names chkfs, repairfs, or fsrepair is associated with filesystem repair in the typical Linux command set, reinforcing that fsck is indeed the correct and widely accepted choice.