fsck(8) BSD System Manager's Manual fsck(8)
NAME
fsck -- filesystem consistency check and interactive repair
SYNOPSIS
fsck -p [-f]
fsck [-l maxparallel] [-q] [-y] [-n] [-d]
DESCRIPTION
The first form of fsck preens a standard set of filesystems or the speci-
fied filesystems. It is normally used in the script /etc/rc during auto-
matic reboot. Here fsck reads the filesystem descriptor table (using
getfsent(3)) to determine which filesystems to check. Only partitions
that have ``rw,'' ``rq'' or ``ro'' as options, and that have non-zero
pass number are checked. Filesystems with pass number 1 (normally just
the root filesystem) are checked one at a time. When pass 1 completes,
all remaining filesystems are checked, running one process per disk
drive. The disk drive containing each filesystem is inferred from the
shortest prefix of the device name that ends in one or more digits; the
remaining characters are assumed to be the partition designator. In
preening mode, filesystems that are marked clean are skipped. Filesys-
tems are marked clean when they are unmounted, when they have been
mounted read-only, or when fsck runs on them successfully.
It should be noted that fsck is now essentially a wrapper that invokes
other fsck_XXX utilities as needed. Currently, fsck can invoke fsck_hfs,
fsck_msdos, fsck_exfat, and fsck_udf. If this underlying process that
fsck invokes encounters serious inconsistencies or the filesystem type is
not one of the above, it exits with an abnormal return status and an
automatic reboot will then fail. For each corrected inconsistency one or
more lines will be printed identifying the filesystem on which the cor-
rection will take place, and the nature of the correction.
If sent a QUIT signal, fsck will finish the filesystem checks, then exit
with an abnormal return status that causes an automatic reboot to fail.
This is useful when you want to finish the filesystem checks during an
automatic reboot, but do not want the machine to come up multiuser after
the checks complete.
Without the -p option, fsck audits and interactively repairs inconsistent
conditions for filesystems. It should be noted that some of the correc-
tive actions which are not correctable under the -p option will result in
some loss of data. The amount and severity of data lost may be deter-
mined from the diagnostic output. If the operator does not have write
permission on the filesystem fsck will default to a -n action.
The following flags are interpreted by fsck and passed along to the
underlying tool that it spawns.
-f Force fsck to check `clean' filesystems when preening.
-l Limit the number of parallel checks to the number specified
in the following argument. By default, the limit is the num-
ber of disks, running one process per disk. If a smaller
limit is given, the disks are checked round-robin, one
filesystem at a time.
-p "Preen" mode, described above.
-q Do a quick check to determine if the filesystem was unmounted
cleanly.
-y Assume a yes response to all questions asked by fsck; this
should be used with great caution as this is a free license
to continue after essentially unlimited trouble has been
encountered.
-n Assume a no response to all questions asked by fsck except
for `CONTINUE?', which is assumed to be affirmative; do not
open the filesystem for writing.
If no filesystems are given to fsck then a default list of filesystems is
read using getfsent(3).
Because of inconsistencies between the block device and the buffer cache,
the raw device should always be used.
SEE ALSO
fs(5), fsck_hfs(8), fsck_msdos(8), getfsent(3), reboot(8)
4th Berkeley Distribution May 18, 2010 4th Berkeley Distribution
Mac OS X 10.8 - Generated Tue Sep 4 05:24:49 CDT 2012