focal (5) fstab.5.gz

Provided by: mount_2.34-0.1ubuntu9.6_amd64 bug

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
       maintain  this file.  The order of records in fstab is important because fsck(8), mount(8), and umount(8)
       sequentially iterate through fstab doing 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 or remote filesystem to be mounted.

              For ordinary mounts, it will hold (a link to) a block special device node (as created by mknod(8))
              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 partitions 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 representation of the UUID should be based on
              lower case characters.

       The second field (fs_file).
              This field describes the mount point (target) for the filesystem.  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, hfsplus, 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 swapping, 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 contains at least the type of mount (ro
              or rw), plus any additional options appropriate to the  filesystem  type  (including  performance-
              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 exist.

       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 available 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 getmntent(3) or libmount.

       The keyword ignore as a filesystem type (3rd field) is no longer supported 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/.