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

NAME

     fsck -- file system consistency check and interactive repair

SYNOPSIS

     fsck [-Cdfnpvy] [-B | -F] [-T fstype:fsoptions] [-t fstype] [-c fstab] [special | node] ...

DESCRIPTION

     The fsck utility 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.  Traditionally, fsck is invoked before the file systems are mounted and
     all checks are done to completion at that time.  If background checking is available, fsck is invoked twice.  It is first invoked at the tra-
     ditional time, before the file systems are mounted, with the -F flag to do checking on all the file systems that cannot do background check-
     ing.  It is then invoked a second time, after the system has completed going multiuser, with the -B flag to do checking on all the file sys-
     tems that can do background checking.  Unlike the foreground checking, the background checking is started asynchronously so that other system
     activity can proceed even on the file systems that are being checked.

     If no file systems are specified, fsck reads the table /etc/fstab to determine which file systems to check.  Only partitions in /etc/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 always checked one at a time.

     If not in preen mode, the remaining entries are checked in order of increasing pass number one at a time.	This is needed when interaction
     with fsck is required.

     In preen mode, after pass 1 completes, all remaining file systems are checked, in pass number order running one process per disk drive in
     parallel for each pass number in increasing order.

     In other words: In preen mode all pass 1 partitions are checked sequentially.  Next all pass 2 partitions are checked in parallel, one
     process per disk drive.  Next all pass 3 partitions are checked in parallel, one process per disk drive.  etc.

     The disk drive containing each file system is inferred from the shortest prefix of the device name that ends in a digit; the remaining char-
     acters are assumed to be the partition and slice designators.

     If the -t or -T flags are not specified, fsck will attempt to determine the file system type and call the appropriated file system check
     utility.  Failure to detect the file system type will cause fsck to fail with a message that the partition has an unknown file system type.

     The options are as follows:

     -C      Check if the ``clean'' flag is set in the superblock and skip file system checks if file system was properly dismounted and marked
	     clean.

     -c fstab
	     Specify the fstab file to use.

     -d      Debugging mode.  Just print the commands without executing them.  Available only if fsck is compiled to support it.

     -f      Force checking of file systems, even when they are marked clean (for file systems that support this).

     -n      Causes fsck to assume no as the answer to all operator questions, except "CONTINUE?".

     -p      Enter preen mode.	In preen mode, only a restricted class of innocuous file system inconsistencies will be corrected.  If unexpected
	     inconsistencies caused by hardware or software failures are encountered, the check program will exit with a failure.  See the manual
	     pages for the individual check programs for a list of the sorts of failures that they correct when running in preen mode.

     -F      Run in foreground mode.  The check program for each file system is invoked with the -F flag to determine whether it wishes to run as
	     part of the boot up sequence, or if it is able to do its job in background after the system is up and running.  A non-zero exit code
	     indicates that it wants to run in foreground and the check program is invoked.  A zero exit code indicates that it is able to run
	     later in background and just a deferred message is printed.

     -B      Run in background mode.  The check program for each file system is invoked with the -F flag to determine whether it wishes to run as
	     part of the boot up sequence, or if it is able to do its job in background after the system is up and running.  A non-zero exit code
	     indicates that it wanted to run in foreground which is assumed to have been done, so the file system is skipped.  A zero exit code
	     indicates that it is able to run in background so the check program is invoked with the -B flag to indicate that a check on the
	     active file system should be done.  When running in background mode, only one file system at a time will be checked.  Note that back-
	     ground fsck is limited to checking for only the most commonly occurring file system abnormalities.  Under certain circumstances, some
	     errors can escape background fsck.  It is recommended that you perform foreground fsck on your systems periodically and whenever you
	     encounter file-system-related panics.

     -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.

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

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

FILES

     /etc/fstab  file system table

SEE ALSO

     fstab(5), fsck_ffs(8), fsck_msdosfs(8), mount(8)

BSD
								   May 23, 2014 							       BSD