FSTAB(5)



FSTAB(5)                         File Formats                         FSTAB(5)

NAME
       fstab - static information about the filesystems

SYNOPSIS
       /etc/fstab

DESCRIPTION
       The  file  fstab contains descriptive information about the filesystems
       the system can mount.  fstab is only read by programs, and not written;
       it is the duty of the system administrator to properly create and main-
       tain this file.  The order of records in  fstab  is  important  because
       fsck(8), mount(8), and umount(8) sequentially iterate through fstab do-
       ing their thing.

       Each filesystem is described on a separate line.  Fields on  each  line
       are separated by tabs or spaces.  Lines starting with '#' are comments.
       Blank lines are ignored.

       The following is a typical example of an fstab entry:

              LABEL=t-home2   /home      ext4    defaults,auto_da_alloc      0
              2

       The first field (fs_spec).
              This field describes the block special device, remote filesystem
              or filesystem image for loop device to be mounted or  swap  file
              or swap partition to be enabled.

              For  ordinary  mounts,  it will hold (a link to) a block special
              device node (as created  by  mknod(2))  for  the  device  to  be
              mounted, like `/dev/cdrom' or `/dev/sdb7'.  For NFS mounts, this
              field is <host>:<dir>, e.g., `knuth.aeb.nl:/'.  For  filesystems
              with  no  storage,  any  string can be used, and will show up in
              df(1) output, for example.  Typical usage is `proc' for  procfs;
              `mem', `none', or `tmpfs' for tmpfs.  Other special filesystems,
              like udev and sysfs, are typically not listed in fstab.

              LABEL=<label> or UUID=<uuid> may be given instead  of  a  device
              name.  This is the recommended method, as device names are often
              a coincidence of hardware detection order, and can  change  when
              other  disks are added or removed.  For example, `LABEL=Boot' or
              `UUID=3e6be9de-8139-11d1-9106-a43f08d823a6'.  (Use a filesystem-
              specific  tool  like e2label(8), xfs_admin(8), or fatlabel(8) to
              set LABELs on filesystems).

              It's also possible to use PARTUUID= and PARTLABEL=. These parti-
              tions  identifiers  are supported for example for GUID Partition
              Table (GPT).

              See mount(8), blkid(8) or lsblk(8) for more details about device
              identifiers.

              Note that mount(8) uses UUIDs as strings. The string representa-
              tion of the UUID should be based on lower case characters.

       The second field (fs_file).
              This field describes the mount point (target) for  the  filesys-
              tem.   For  swap  partitions,  this field should be specified as
              `none'. If the name of the mount point contains spaces  or  tabs
              these can be escaped as `\040' and '\011' respectively.

       The third field (fs_vfstype).
              This field describes the type of the filesystem.  Linux supports
              many filesystem types: ext4, xfs, btrfs, f2fs, vfat, ntfs,  hfs-
              plus, tmpfs, sysfs, proc, iso9660, udf, squashfs, nfs, cifs, and
              many more.  For more details, see mount(8).

              An entry swap denotes a file or partition to be used  for  swap-
              ping,  cf.  swapon(8).  An entry none is useful for bind or move
              mounts.

              More than one type may be specified in a comma-separated list.

              mount(8) and umount(8) support filesystem subtypes.  The subtype
              is defined by '.subtype' suffix.  For example 'fuse.sshfs'. It's
              recommended to use subtype notation rather than add  any  prefix
              to  the  first  fstab  field (for example 'sshfs#example.com' is
              deprecated).

       The fourth field (fs_mntops).
              This field describes  the  mount  options  associated  with  the
              filesystem.

              It  is  formatted as a comma-separated list of options.  It con-
              tains at least the type of mount (ro or rw), plus any additional
              options  appropriate  to  the filesystem type (including perfor-
              mance-tuning options).  For details, see mount(8) or swapon(8).

              Basic filesystem-independent options are:

              defaults
                     use default options: rw, suid, dev, exec,  auto,  nouser,
                     and async.

              noauto do  not  mount  when  "mount  -a" is given (e.g., at boot
                     time)

              user   allow a user to mount

              owner  allow device owner to mount

              comment
                     or x-<name> for use by fstab-maintaining programs

              nofail do not report errors for this device if it does  not  ex-
                     ist.

       The fifth field (fs_freq).
              This  field  is  used  by dump(8) to determine which filesystems
              need to be  dumped.   Defaults  to  zero  (don't  dump)  if  not
              present.

       The sixth field (fs_passno).
              This  field  is  used by fsck(8) to determine the order in which
              filesystem checks are done at boot time.   The  root  filesystem
              should  be  specified  with a fs_passno of 1.  Other filesystems
              should have a fs_passno of 2.  Filesystems within a  drive  will
              be  checked  sequentially,  but  filesystems on different drives
              will be checked at the same time to utilize  parallelism  avail-
              able  in  the  hardware.   Defaults  to zero (don't fsck) if not
              present.

NOTES
       The proper way to read records from fstab is to use the routines getmn-
       tent(3) or libmount.

       The  keyword  ignore as a filesystem type (3rd field) is no longer sup-
       ported by the pure  libmount  based  mount  utility  (since  util-linux
       v2.22).

FILES
       /etc/fstab, <fstab.h>

SEE ALSO
       getmntent(3), fs(5), findmnt(8), mount(8), swapon(8)

HISTORY
       The ancestor of this fstab file format appeared in 4.0BSD.

AVAILABILITY
       This  man  page is part of the util-linux package and is available from
       https://www.kernel.org/pub/linux/utils/util-linux/.

util-linux                       February 2015                        FSTAB(5)

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