Generic fsck Command Syntax, Options, and Arguments
The fsck command has two components: a generic component
and a component specific to each type of file system. The generic commands
apply to most types of file systems, while the specific commands apply to
only one type of file system. You should always use the generic command, which
calls the file system-specific command, as needed.
Usually, you must be superuser to run fsck. You can
run the fsck command without being superuser; but to make
repairs, you should unmount the file system and you must have read permission
for the raw device file for the slice (a potential security hole).
The generic fsck command goes through /etc/vfstab to see what file systems to check. It runs the appropriate
file system-specific fsck command on each file system listed,
except those excluded by an fsck pass number of - or 0 (UFS only).
The generic fsck command has the following syntax:
/usr/sbin/fsck [-F type] [-V] [-m] [special]
/usr/sbin/fsck [-F type] [-V] [-y|Y|n|N] [-o specific-options][special]
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The table below describes the options and arguments to the generic fsck command.
Table 39-4
The
fsck Command Options and
Arguments
Option Type
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Option
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Description
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Generic
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-F
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Specifies the file system type (type). If type is not specified on the command line, it is obtained from /etc/vfstab by matching an entry in that file with the special
device name specified. If no entry is found, the default local file system
type specified in /etc/default/fs is used.
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-V
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Echoes the completed command line (verbose). The echoed line includes additional
information derived from /etc/vfstab. This option can
be used to verify and validate the command line. It does not execute the command.
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-m
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Performs a preliminary check only. It returns a code indicating the state
of the file system: 0 for "clean" and 32 for "dirty." This option is used by the startup script /sbin/rcS to determine whether a file system needs to be checked.
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-y or -Y or -n or -N
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Runs the command automatically answering yes or no to all prompts.
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c
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Converts an old pre-SunOS 4.1 file system with statically
allocated tables to new dynamically allocated tables. Static allocation imposes
a hard maximum on table size, while dynamic allocation means space for tables
can be added as needed after the initial allocation. If the file system is
in the new format, convert it to the old format, unless the table allocation
exceeds the fixed maximum allowed in the old format. fsck
lists the direction of the conversion. In interactive mode, fsck prompts for confirmation before doing the conversion. When you
use the -o p option, the conversion is attempted without asking
for confirmation. This option is useful when you want to convert a number
of file systems at once. You can determine whether a file system is in the
old or new format by running the fstyp command, and looking
at the first line displayed.
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w
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Checks only file systems that permit write access.
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special
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Specifies the mount point or raw device name
of one or more file systems. An entry for the mount point must exist in /etc/vfstab. If you omit the special
argument, entries in /etc/vfstab with a specified fsck device and a fsck pass number greater than
zero are checked. If preening (-o p) is in effect and more
than one entry has an fsck pass number greater than 1,
file systems on different disks are checked in parallel.
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Specific
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This is a comma-separated list of options that follow the -o
option. Describes the options that are passed to the UFS-specific fsck command for interpretation.
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p
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Preens. Runs the command automatically in silent mode,
correcting what it can, but exiting when it encounters a problem that requires
intervention. This option also enables parallel checking of UFS file systems.
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b=blocknumber
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Uses the alternative (redundant) superblock,
located at the specified location. This option can be used to repair a bad
superblock. You can display a list of alternative superblocks by using the newfs -N command.
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