The /etc/fstab
file can be used to define how disk partitions, various other block devices, or
remote filesystems should be mounted into the filesystem.
Each filesystem is described in a separate line. These definitions will be converted into systemd mount units dynamically at boot, and when the configuration of the system manager is reloaded. The default setup will automatically fsck and mount filesystems before starting services that need them to be mounted. For example, systemd automatically makes sure that remote filesystem mounts like NFS or Samba are only started after the network has been set up. Therefore, local and remote filesystem mounts specified in
The
In this section, we will describe how to mount filesystems using all the mount methods available via examples. The output of the commands
Reference: https://wiki.archlinux.org/index.php/Fstab
Each filesystem is described in a separate line. These definitions will be converted into systemd mount units dynamically at boot, and when the configuration of the system manager is reloaded. The default setup will automatically fsck and mount filesystems before starting services that need them to be mounted. For example, systemd automatically makes sure that remote filesystem mounts like NFS or Samba are only started after the network has been set up. Therefore, local and remote filesystem mounts specified in
/etc/fstab should work out of the box.
See man 5
systemd.mount for details. The
mount
command will use fstab, if just one of either directory or device is given, to
fill in the value for the other parameter. When doing so, mount options which
are listed in fstab will also be used.
File
example
A simple /etc/fstab, using kernel name descriptors:
/etc/fstab
# <file system> <dir> <type> <options> <dump> <pass>
/dev/sda1 / ext4 defaults,noatime 0
1
/dev/sda2 none swap defaults 0
0
/dev/sda3 /home ext4 defaults,noatime 0
2
Field
definitions
Each line in the /etc/fstab file contains the following fields separated by spaces or
tabs:
file_system dir type options dump pass
file system
The partition or storage device to be mounted.
dir
The mountpoint where <file system> is mounted to.
type
The file system type of the partition or storage device to
be mounted. Many different file systems are supported: ext2, ext3,
ext4, btrfs, reiserfs, xfs,
jfs, smbfs, iso9660, vfat,
ntfs, swap and auto.
The auto type lets the mount command guess
what type of file system is used. This is useful for optical media (CD/DVD).
options
Mount options of the filesystem to be used. See the mount
man page. Please note that some options are specific to filesystems; to
discover them see below in the aforementioned mount man page.
dump
Used by the dump utility to decide when to make a backup.
Dump checks the entry and uses the number to decide if a file system should be
backed up. Possible entries are 0 and 1. If 0, dump will ignore the file
system; if 1, dump will make a backup. Most users will not have dump installed,
so they should put 0 for the dump entry.
pass
Used by fsck to decide which order filesystems are to be checked.
Possible entries are 0, 1 and 2. The root file system should have the highest
priority 1 (unless its type is btrfs, in
which case this field should be 0) - all other file systems you want to have
checked should have a 2. File systems with a value 0 will not be checked by the
fsck utility.
Identifying filesystems
There are different ways to identify filesystems that will be mounted./etc/fstab
does support several methods: kernel name descriptor, label or UUID, and GPT
labels and UUID for GPT disks. UUID must be privileged over kernel name
descriptors and labels. See Persistent block device naming for
more explanations. It is recommended to read that article first before
continuing with this article. In this section, we will describe how to mount filesystems using all the mount methods available via examples. The output of the commands
lsblk -f
and blkid
used in the following examples are available in the article Persistent block device naming. If
you have not read that article yet, please read it now. Kernel name descriptors
Runlsblk
-f to list the partitions and prefix the values in the NAME
column with /dev/.
/etc/fstab
# <file system> <dir> <type> <options> <dump> <pass>
/dev/sda1 /boot vfat rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro 0 2
/dev/sda2 / ext4 rw,relatime,discard,data=ordered 0 1
/dev/sda3 /home ext4 rw,relatime,discard,data=ordered 0 2
/dev/sda4 none swap defaults 0 0
Labels
Runlsblk
-f to list the partitions, and prefix the values in the LABEL
column with LABEL=:
/etc/fstab
# <file system> <dir> <type> <options> <dump> <pass>
LABEL=EFI /boot vfat rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro 0 2
LABEL=SYSTEM / ext4 rw,relatime,discard,data=ordered 0 1
LABEL=DATA /home ext4 rw,relatime,discard,data=ordered 0 2
LABEL=SWAP none swap defaults 0 0
Note:
If any of your fields contains spaces, see #Filepath
spaces.
UUIDs
Runlsblk
-f to list the partitions, and prefix the values in the UUID
column with UUID=:
/etc/fstab
# <file system> <dir> <type> <options> <dump> <pass>
UUID=CBB6-24F2 /boot vfat rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro 0 2
UUID=0a3407de-014b-458b-b5c1-848e92a327a3 / ext4 rw,relatime,discard,data=ordered 0 1
UUID=b411dc99-f0a0-4c87-9e05-184977be8539 /home ext4 rw,relatime,discard,data=ordered 0 2
UUID=f9fe0b69-a280-415d-a03a-a32752370dee none swap defaults 0 0
Tip:
If you would like to return just the UUID of a specific
partition: $ lsblk -no UUID /dev/sda2
GPT labels
Runblkid
to list the partitions, and use the PARTLABEL values without the quotes:
/etc/fstab
# <file system> <dir> <type> <options> <dump> <pass>
PARTLABEL=EFI\040SYSTEM\040PARTITION /boot vfat rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro 0 2
PARTLABEL=GNU/LINUX / ext4 rw,relatime,discard,data=ordered 0 1
PARTLABEL=HOME /home ext4 rw,relatime,discard,data=ordered 0 2
PARTLABEL=SWAP none swap defaults 0 0
Note:
If any of your fields contains spaces, see #Filepath
spaces.
GPT UUIDs
Runblkid
to list the partitions, and use the PARTUUID values without the quotes: /etc/fstab
# <file system> <dir> <type> <options> <dump> <pass>
PARTUUID=d0d0d110-0a71-4ed6-936a-304969ea36af /boot vfat rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro 0 2
PARTUUID=98a81274-10f7-40db-872a-03df048df366 / ext4 rw,relatime,discard,data=ordered 0 1
PARTUUID=7280201c-fc5d-40f2-a9b2-466611d3d49e /home ext4 rw,relatime,discard,data=ordered 0 2
PARTUUID=039b6c1c-7553-4455-9537-1befbc9fbc5b none swap defaults 0 0
Tips and tricks
Automount with systemd
If you have a large/home partition, it might be better to
allow services that do not depend on /home to start while /home
is checked by fsck. This can be achieved by adding the following options
to the /etc/fstab
entry of your /home
partition: noauto,x-systemd.automountThis will fsck and mount
/home when it is first accessed, and the
kernel will buffer all file access to /home until it is ready.
Note:
This will make your
The same applies to remote filesystem mounts. If you want them to be mounted
only upon access, you will need to use the /home filesystem type autofs,
which is ignored by mlocate by default. The speedup of automounting /home
may not be more than a second or two, depending on your system, so this trick
may not be worth it.noauto,x-systemd.automount parameters.
In addition, you can use the x-systemd.device-timeout=# option to
specify a timeout in case the network resource is not available.
Note:
If you intend to use the
If you have encrypted filesystems with keyfiles, you can also add the exec flag with automount, you
should remove the user flag for it to work properly as found in the
course of a Fedora
Bug Reportnoauto
parameter to the corresponding entries in /etc/crypttab. systemd will then
not open the encrypted device on boot, but instead wait until it is actually
accessed and then automatically open it with the specified keyfile before
mounting it. This might save a few seconds on boot if you are using an
encrypted RAID device for example, because systemd does not have to wait for
the device to become available. For example: /etc/crypttab
data /dev/md0 /root/key noauto
Filepath spaces
Since spaces are used infstab to delimit fields, if any field (PARTLABEL,
LABEL or the mount point) contains spaces, these spaces must be replaced
by escape characters \ followed by the 3 digit octal code 040: /etc/fstab
UUID=47FA-4071 /home/username/Camera\040Pictures vfat defaults,noatime 0 0
/dev/sda7 /media/100\040GB\040(Storage) ext4 defaults,noatime,user 0 2
External devices
External devices that are to be mounted when present but ignored if absent may require thenofail
option. This prevents errors being reported at boot. /etc/fstab
/dev/sdg1 /media/backup jfs defaults,nofail 0 2
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