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FSCK(8)                     System Manager's Manual                    FSCK(8)

     fsck - file system consistency check and interactive repair

     fsck [-dfnPpqvy] [-l maxparallel] [-T fstype:fsoptions] [-t fstype]
          [-x mountpoint] [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

     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

     -l maxparallel
             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

     -n      Causes fsck to 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, fsck will 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.

     -T fstype:fsoptions
             List of comma separated file system specific options for the
             specified file system type, in the same format as mount(8).

     -t fstype
             Invoke fsck only for the comma separated list of file system
             types.  If the list starts with "no" then invoke fsck for the
             file system types that are not specified in the list.

     -v      Print the commands before executing them.

     -x mountpoint
             Exclude the file system which has a mountpoint the same as in
             /etc/fstab.  Used only in "preen" mode.

     -y      Causes fsck to assume yes as the answer to all operator

     /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 fsck
           on 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

     8     The file system check has failed, and a subsequent check is
           required that will require human intervention.

     12    fsck exited because of the result of a signal (usually SIGINT or
           SIGQUIT from the terminal).

     fstab(5), fsck_ext2fs(8), fsck_ffs(8), fsck_lfs(8), fsck_msdos(8),

     An fsck 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.

NetBSD 9.99                     April 18, 2020                     NetBSD 9.99