bionic (8) fsck.8.gz

Provided by: util-linux_2.31.1-0.4ubuntu3.7_amd64 bug

NAME

       fsck - check and repair a Linux filesystem

SYNOPSIS

       fsck [-lsAVRTMNP] [-r [fd]] [-C [fd]] [-t fstype] [filesystem...] [--] [fs-specific-options]

DESCRIPTION

       fsck  is used to check and optionally repair one or more Linux filesystems.  filesys can be a device name
       (e.g.  /dev/hdc1, /dev/sdb2), a mount point (e.g.  /, /usr, /home), or an ext2 label  or  UUID  specifier
       (e.g.   UUID=8868abf6-88c5-4a83-98b8-bfc24057f7bd or LABEL=root).  Normally, the fsck program will try to
       handle filesystems on different physical disk drives in parallel to  reduce  the  total  amount  of  time
       needed to check all of them.

       If  no  filesystems  are  specified  on  the  command line, and the -A option is not specified, fsck will
       default to checking filesystems in /etc/fstab serially.  This is equivalent to the -As options.

       The exit code returned by fsck is the sum of the following conditions:

              0      No errors
              1      Filesystem errors corrected
              2      System should be rebooted
              4      Filesystem errors left uncorrected
              8      Operational error
              16     Usage or syntax error
              32     Checking canceled by user request
              128    Shared-library error

       The exit code returned when multiple filesystems are checked is the bit-wise OR of  the  exit  codes  for
       each filesystem that is checked.

       In  actuality,  fsck  is  simply  a front-end for the various filesystem checkers (fsck.fstype) available
       under Linux.  The filesystem-specific checker is searched for in the PATH environment  variable.  If  the
       PATH is undefined then fallback to "/sbin".

       Please see the filesystem-specific checker manual pages for further details.

OPTIONS

       -l     Create  an  exclusive  flock(2) lock file (/run/fsck/<diskname>.lock) for whole-disk device.  This
              option can be used with one device only (this means that -A and -l are mutually exclusive).   This
              option  is  recommended  when more fsck(8) instances are executed in the same time.  The option is
              ignored when used for multiple devices or for non-rotating disks.  fsck does not  lock  underlying
              devices  when  executed to check stacked devices (e.g. MD or DM) – this feature is not implemented
              yet.

       -r [fd]
              Report certain statistics for each fsck when it completes.   These  statistics  include  the  exit
              status,  the  maximum  run  set  size  (in kilobytes), the elapsed all-clock time and the user and
              system CPU time used by the fsck run.  For example:

              /dev/sda1: status 0, rss 92828, real 4.002804, user 2.677592, sys 0.86186

              GUI front-ends may specify a file descriptor fd, in which case the progress bar  information  will
              be sent to that file descriptor in a machine parsable format.  For example:

              /dev/sda1 0 92828 4.002804 2.677592 0.86186

       -s     Serialize  fsck  operations.  This is a good idea if you are checking multiple filesystems and the
              checkers are in an interactive mode.  (Note: e2fsck(8) runs in an interactive mode by default.  To
              make  e2fsck(8) run in a non-interactive mode, you must either specify the -p or -a option, if you
              wish for errors to be corrected automatically, or the -n option if you do not.)

       -t fslist
              Specifies the type(s) of  filesystem  to  be  checked.   When  the  -A  flag  is  specified,  only
              filesystems  that  match  fslist  are  checked.  The fslist parameter is a comma-separated list of
              filesystems and options specifiers.  All of the filesystems in this comma-separated  list  may  be
              prefixed by a negation operator 'no' or '!', which requests that only those filesystems not listed
              in fslist will be checked.  If none of the  filesystems  in  fslist  is  prefixed  by  a  negation
              operator, then only those listed filesystems will be checked.

              Options  specifiers  may  be  included  in  the comma-separated fslist.  They must have the format
              opts=fs-option.  If an options specifier is present, then only filesystems which contain fs-option
              in  their mount options field of /etc/fstab will be checked.  If the options specifier is prefixed
              by a negation operator, then only those filesystems that do not  have  fs-option  in  their  mount
              options field of /etc/fstab will be checked.

              For  example, if opts=ro appears in fslist, then only filesystems listed in /etc/fstab with the ro
              option will be checked.

              For compatibility with Mandrake distributions whose boot scripts depend upon  an  unauthorized  UI
              change  to  the fsck program, if a filesystem type of loop is found in fslist, it is treated as if
              opts=loop were specified as an argument to the -t option.

              Normally, the filesystem type is deduced by searching for filesys in the /etc/fstab file and using
              the  corresponding  entry.   If  the type cannot be deduced, and there is only a single filesystem
              given as an argument to the -t option, fsck will use the specified filesystem type.  If this  type
              is not available, then the default filesystem type (currently ext2) is used.

       -A     Walk  through  the  /etc/fstab  file  and try to check all filesystems in one run.  This option is
              typically used from the /etc/rc system initialization  file,  instead  of  multiple  commands  for
              checking a single filesystem.

              The  root  filesystem  will be checked first unless the -P option is specified (see below).  After
              that, filesystems will be checked in the order specified by the fs_passno (the sixth) field in the
              /etc/fstab  file.  Filesystems with a fs_passno value of 0 are skipped and are not checked at all.
              Filesystems with a fs_passno value of greater than zero will be checked in order, with filesystems
              with  the lowest fs_passno number being checked first.  If there are multiple filesystems with the
              same pass number, fsck will attempt to check them in parallel,  although  it  will  avoid  running
              multiple filesystem checks on the same physical disk.

              fsck does not check stacked devices (RAIDs, dm-crypt, ...) in parallel with any other device.  See
              below for FSCK_FORCE_ALL_PARALLEL setting.  The /sys filesystem is used to determine  dependencies
              between devices.

              Hence,  a  very  common  configuration in /etc/fstab files is to set the root filesystem to have a
              fs_passno value of 1 and to set all other filesystems to have a fs_passno value of 2.   This  will
              allow  fsck  to  automatically run filesystem checkers in parallel if it is advantageous to do so.
              System administrators might choose not to use this configuration if they need  to  avoid  multiple
              filesystem checks running in parallel for some reason – for example, if the machine in question is
              short on memory so that excessive paging is a concern.

              fsck normally does not check whether the  device  actually  exists  before  calling  a  filesystem
              specific  checker.  Therefore non-existing devices may cause the system to enter filesystem repair
              mode during boot if the filesystem specific checker returns a fatal error.  The  /etc/fstab  mount
              option  nofail  may  be used to have fsck skip non-existing devices.  fsck also skips non-existing
              devices that have the special filesystem type auto.

       -C [fd]
              Display completion/progress bars for those filesystem checkers (currently only for ext[234]) which
              support  them.   fsck  will manage the filesystem checkers so that only one of them will display a
              progress bar at a time.  GUI front-ends may specify a  file  descriptor  fd,  in  which  case  the
              progress bar information will be sent to that file descriptor.

       -M     Do not check mounted filesystems and return an exit code of 0 for mounted filesystems.

       -N     Don't execute, just show what would be done.

       -P     When  the  -A flag is set, check the root filesystem in parallel with the other filesystems.  This
              is not the safest thing in the world to do, since if the root filesystem is in doubt  things  like
              the  e2fsck(8)  executable might be corrupted!  This option is mainly provided for those sysadmins
              who don't want to repartition the root filesystem to be small and compact  (which  is  really  the
              right solution).

       -R     When checking all filesystems with the -A flag, skip the root filesystem.  (This is useful in case
              the root filesystem has already been mounted read-write.)

       -T     Don't show the title on startup.

       -V     Produce verbose output, including all filesystem-specific commands that are executed.

       -?, --help
              Display help text and exit.

       --version
              Display version information and exit.

FILESYSTEM SPECIFIC OPTIONS

       Options which are not understood by fsck are passed to the filesystem-specific checker!

       These options must not take arguments, as there is no way for fsck to be able  to  properly  guess  which
       options take arguments and which don't.

       Options  and arguments which follow the -- are treated as filesystem-specific options to be passed to the
       filesystem-specific checker.

       Please note that fsck is not designed to pass  arbitrarily  complicated  options  to  filesystem-specific
       checkers.   If  you're  doing  something complicated, please just execute the filesystem-specific checker
       directly.  If you pass fsck some horribly complicated options and arguments, and it doesn't do  what  you
       expect,  don't  bother reporting it as a bug.  You're almost certainly doing something that you shouldn't
       be doing with fsck.  Options to different filesystem-specific fsck's are not standardized.

FILES

       /etc/fstab

ENVIRONMENT VARIABLES

       The fsck program's behavior is affected by the following environment variables:

       FSCK_FORCE_ALL_PARALLEL
              If this environment variable is set, fsck will attempt to check all of the  specified  filesystems
              in  parallel,  regardless  of  whether  the filesystems appear to be on the same device.  (This is
              useful for RAID systems or high-end storage systems such as those sold by companies such as IBM or
              EMC.)  Note that the fs_passno value is still used.

       FSCK_MAX_INST
              This environment variable will limit the maximum number of filesystem checkers that can be running
              at one time.  This allows configurations which have a large number of disks to avoid fsck starting
              too  many  filesystem checkers at once, which might overload CPU and memory resources available on
              the system.  If this value is zero, then an unlimited number of processes can be spawned.  This is
              currently the default, but future versions of fsck may attempt to automatically determine how many
              filesystem checks can be run based on gathering accounting data from the operating system.

       PATH   The PATH environment variable is used to find filesystem checkers.

       FSTAB_FILE
              This environment variable allows the system administrator to override the standard location of the
              /etc/fstab file.  It is also useful for developers who are testing fsck.

       LIBBLKID_DEBUG=all
              enables libblkid debug output.

       LIBMOUNT_DEBUG=all
              enables libmount debug output.

SEE ALSO

       fstab(5), mkfs(8), fsck.ext2(8) or fsck.ext3(8) or e2fsck(8), cramfsck(8), fsck.jfs(8), fsck.nfs(8),
       fsck.minix(8), fsck.msdos(8), fsck.vfat(8), fsck.xfs(8), reiserfsck(8)

AUTHORS

       Theodore Ts'o <tytso@mit.edu>
       Karel Zak <kzak@redhat.com>

AVAILABILITY

       The fsck command is part of the util-linux package and is available from Linux Kernel  Archive  ⟨https://
       www.kernel.org/pub/linux/utils/util-linux/⟩.