fsck

Check the integrity of a filesystem or repair it. The filesystem should be unmounted at the time the command is run. It is a wrapper that calls fsck_hfs, fsck_apfs, fsck_msdos, fsck_exfat, and fsck_udf as needed. More information: https://ss64.com/osx/fsck.html.

• Check filesystem /dev/sdX, reporting any damaged blocks:
  fsck {{/dev/sdX}}
• Check filesystem /dev/sdX only if it is clean, reporting any damaged blocks and interactively letting the user choose to repair each one:
  fsck -f {{/dev/sdX}}
• Check filesystem /dev/sdX only if it is clean, reporting any damaged blocks and automatically repairing them:
  fsck -fy {{/dev/sdX}}
• Check filesystem /dev/sdX, reporting whether it has been cleanly unmounted:
  fsck -q {{/dev/sdX}}