fsck —
file system consistency check and interactive repair
  
    | fsck | [ -dfnPpqvy] [-lmaxparallel] [-Tfstype:fsoptions] [-tfstype] [-xmountpoint] [special | node ...] | 
The fsck command invokes file system-specific programs
  to check the special devices listed in the
  fstab(5) file or in the command
  line for consistency.
It is normally used in the script /etc/rc
    during automatic reboot. If no file systems are specified, and
    “preen” mode is enabled ( -p option)
    fsck reads the table
    /etc/fstab to determine which file systems to check,
    in what order. Only partitions in fstab that are mounted ``rw,'' ``rq'' or
    ``ro'' and that have non-zero pass number are checked. File systems with
    pass number 1 (normally just the root file system) are checked one at a
    time. When pass 1 completes, all remaining file systems are checked, running
    one process per disk drive. By default, file systems which are already
    mounted read-write are not checked. The disk drive containing each file
    system is inferred from the longest prefix of the device name that ends in a
    digit; the remaining characters are assumed to be the partition
  designator.
The options are as follows:
  - -d
- Debugging mode. Just print the commands without executing them.
- -f
- Force checking of file systems, even when they are marked clean (for file
      systems that support this), or when they are mounted read-write.
- -lmaxparallel
- Limit the number of parallel checks to the number specified in the
      following argument. By default, the limit is the number of disks, running
      one process per disk. If a smaller limit is given, the disks are checked
      round-robin, one file system at a time.
- -n
- Causes fsckto assume no as the answer to all
      operator questions, except "CONTINUE?".
- -P
- Display a progress meter for each file system check. This option also
      disables parallel checking. Note that progress meters are not supported by
      all file system types.
- -p
- Enter preen mode. In preen mode, fsckwill check
      all file systems listed in /etc/fstab according to
      their pass number, and will make minor repairs without human
    intervention.
- -q
- Quiet mode, do not output any messages for clean file systems.
- -Tfstype:fsoptions
- List of comma separated file system specific options for the specified
      file system type, in the same format as
      mount(8).
- -tfstype
- Invoke fsckonly for the comma separated list of
      file system types. If the list starts with “no” then invokefsckfor the file system types that are not
      specified in the list.
- -v
- Print the commands before executing them.
- -xmountpoint
- Exclude the file system which has a mountpoint the
      same as in /etc/fstab. Used only in
      “preen” mode.
- -y
- Causes fsckto assume yes as the answer to all
      operator questions.
  - /etc/fstab
- file system table
fsck exits with 0 on success.
  Any major problems will cause fsck to exit with the
  following non-zero exit(3) codes,
  so as to alert any invoking program or script that human intervention is
  required.
  - 1
- Usage problem.
- 2
- Unresolved errors while checking the file system. Re-running
      fsckon the file system(s) is required.
- 4
- The root file system was changed in the process of checking, and updating
      the mount was unsuccessful. A reboot (without sync) is required.
- 8
- The file system check has failed, and a subsequent check is required that
      will require human intervention.
- 12
- fsckexited because of the result of a signal
      (usually- SIGINTor- SIGQUITfrom the terminal).
Anfsck utility appeared in
  4.0BSD. It was reimplemented as a file system
  independent wrapper in NetBSD 1.3. The original file
  system specific utility became
  fsck_ffs(8) at this point.