FSCK(8) FreeBSD 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
traditional time, before the file systems are mounted, with the -F flag
to do checking on all the file systems that cannot do background
checking. 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 systems 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 characters
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 appropriate 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. Running "fsck -f" ignores the
journal and does a full consistency check of the disk so will
find and fix the errors about which the journal is unaware.
-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 background 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)
HISTORY
A fsck utility appeared in 4.0BSD. It was reimplemented as a filesystem
independent wrapper in NetBSD 1.3 and first appeared in FreeBSD 5.0. The
original filesystem specific utility became fsck_ffs(8) at this point.
FreeBSD 13.1-RELEASE-p6 March 5, 2019 FreeBSD 13.1-RELEASE-p6
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