File-system integrity refers to whether the file-system contains errors.
Sometimes this is caused by a user turning off the computer system without first
shutting the computer down properly. During the shutdown process, a flag can be
written to the file-system. At startup, this flag can be detected, and if not
present, means the computer system was not shut down correctly. UNIX provides
the fsck program to check the file-system. The Windows operating systems provide
Scandisk or Chkdsk (checkdisk).