Fstab/fr

Utilisation de fstab

Le fichier de configuration appartenant à la racine /etc/fstab est utilisé pour définir comment les partitions de disque, divers autres périphériques de bloc, ou les systèmes de fichiers distants doivent être montés dans le système de fichiers.

Chaque système de fichiers est décrit dans une ligne séparée. Ces définitions seront converties en unités de montage systemd dynamiquement au démarrage, ou lorsque la configuration du gestionnaire de système est rechargée.

La commande mount --all montera tous les systèmes de fichiers mentionnés dans fstab, (sauf ceux dont la ligne contient le mot clé noauto). Les systèmes de fichiers sont montés en suivant leur ordre dans fstab. La commande mount compare les systèmes de fichiers source et cible pour détecter les systèmes de fichiers déjà montés. La table du noyau contenant les systèmes de fichiers déjà montés est mise en cache pendant mount --all. Cela signifie que toutes les entrées fstab dupliquées seront montées.

Fichier d'exemple

Chaque ligne du fichier décrit un système de fichiers, et contient des champs (spécifiés en colonnes) utilisés pour fournir des informations sur son point de montage, les options qui doivent être utilisées lors du montage, etc. Chaque champ peut être séparé les uns des autres par des espaces ou des tabulations :

# /etc/fstab : informations statiques sur le système de fichiers.
# <système de fichiers> <point de montage> <type> <options> <dump> <pass>.
LABEL=ESP   /boot/efi   vfat   umask=0077   0   2
/dev/sda5   /           ext4   defaults,noatime,discard   0   1
UUID=18360b04-a96d-4a99-8323-b07717f36a31   swap   swap defaults,noatime,discard   0   0
UUID=b4108631-e051-48d8-b2ff-a1d924a893f1   /home   ext4   defaults,noatime,discard   0   2
tmpfs   /tmp   tmpfs   defaults,noatime,mode=1777   0   0
UUID=634E43D367B0A4B1   /media/Data   ntfs-3g   noauto,x-systemd.automount,x-systemd.device-timeout=10,rw,inherit,permissions,streams_interface=windows,windows_names,compression,norecover,hide_dot_files,hide_hid_files,big_writes   0   2

Chaque colonne dans le tableau ci-dessus correspond aux "champs" de fstab et sera expliquée dans la section suivante.

Spécification du système de fichiers

Ce champ décrit un de chacun des éléments suivants :

• le périphérique spécial de bloc
• le système de fichiers distant
• image du système de fichiers pour le périphérique loop à monter
• le fichier d'échange (swap) ou la partition d'échange à activer

Ce champ prend généralement la forme de :

• /dev/XdY
• LABEL=<label>
• UUID=<uuid>

pour identifier de manière unique un système de fichiers que vous souhaitez monter. Comme un UUID est nécessairement unique, vous constaterez qu'il s'agit de la valeur par défaut utilisée sur les systèmes plus modernes, alors qu'un nom de périphérique et un label ne sont utilisés que sur les systèmes plus anciens. Nous nous concentrerons donc sur les UUID dans ce tutoriel, mais sachez que si vous insistez pour utiliser ces commandes systèmes, elles fonctionnent toujours au moment de la rédaction de ce document.

To get the UUID for all of your devices, execute the command blkid elevated to root:

sudo blkid

and you'll get someting like this:

/dev/sda1: LABEL_FATBOOT="ESP" LABEL="ESP" UUID="2462-755F" BLOCK_SIZE="512" TYPE="vfat" PARTLABEL="EFI system partition" PARTUUID="b86c0cae-3055-4d9e-9e12-1fa1e2cd32d2"
/dev/sda2: PARTLABEL="Microsoft reserved partition" PARTUUID="b0679b89-007c-441b-88a3-74a39f1f8b2b"
/dev/sda3: LABEL="WINSYS" BLOCK_SIZE="512" UUID="029873F49873E497" TYPE="ntfs" PARTLABEL="Basic data partition" PARTUUID="f8d444b9-ec60-4ac8-b12a-52448119fad1"
/dev/sda4: BLOCK_SIZE="512" UUID="0EB23063B2305207" TYPE="ntfs" PARTLABEL="Basic data partition" PARTUUID="cb083fb5-d61c-48e3-a657-ceb363a983b1"
/dev/sda5: UUID="9b539186-41e9-46f0-a515-1ec6c3544367" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="7bd52fb7-4d7d-412c-bc01-e3c98c7f3bb1"
/dev/sda6: UUID="b4108631-e051-48d8-b2ff-a1d924a893f0" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="9683d669-e0fd-496a-bd9c-f0e51d0bd561"
/dev/sda7: UUID="18360b04-a96d-4a99-8323-b07717f36a30" TYPE="swap" PARTUUID="7434de88-dd5c-4ce5-a6e2-4bb65c16eab5"
/dev/sdb2: UUID="26055107-28cd-457e-9a31-46781de4065d" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="86bdde2c-b92c-43fc-811a-6d0cdc312be1"
/dev/sdb3: UUID="c9dd0f4c-5793-446e-90bb-d10e27bf4922" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="d02838bd-371c-4673-96ed-8aad73bb6d91"
/dev/sdc1: LABEL="Win-Data" BLOCK_SIZE="512" UUID="634E43D367B0A4B1" TYPE="ntfs" PARTUUID="ca8d0663-6a6e-4b09-a0d7-05b59d109ab1"

Any one of the output of blkid can be used as the first field in the fstab file.

E.G. all of the following lines are valid entries for the first line of the output of the above example:

# <file system>                           <mount point>  <type>  <options>                     <dump>  <pass>
LABEL=ESP                                 /boot/efi      vfat    umask=0077                         0       2
UUID=2462-755F                            /boot/efi      vfat    umask=0077                         0       2
LABEL=EFI\040system\040partition          /boot/efi      vfat    umask=0077                         0       2
UUID=b86c0cae-3055-4d9e-9e12-1fa1e2cd32d2 /boot/efi      vfat    umask=0077                         0       2

I.E. only one of the above lines should be present in your fstab file to mount the ESP partition, but any of them will work! However it is strongly recommended to use the UUID as that is globally unique!. This means that if your move a disk to another machine, it will keep its UUID and there is no opportunity for surprises like the computer you've moved the existing disk to suddenly:

• booting from the EFI System Partition on the new disk instead of its own ESP
• failing to mount its own Windows partition because you just added another one and this takes precedence (or not: depending on the exact kernel version and filesystem driver resulting in a boot only working 50% of the time and other weird problems)
• failing to mount a disk because the disk you just inserted into M2 slot #1 gets named /dev/sda and the one in slot #2 which used to be called /dev/sda now suddenly becomes /dev/sdb.
• etc, etc.

Mount Point

This field describes the mount point (target) inside your 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.

For more information on the Linux Filesystem Hierarchy standard refer to the #See Also section, but in a nutshell you should specify an existing directory on your filesystem where you want to mount a partition.

In the example fstab file above, the following line in it's blkid output:

/dev/sdc1: LABEL="Win-Data" BLOCK_SIZE="512" UUID="634E43D367B0A4B1" TYPE="ntfs" PARTUUID="ca8d0663-6a6e-4b09-a0d7-05b59d109ab1"

• is the Windows D: Drive
• has an NTFS label of "Win-Data"
• has a Windows UUID of "634E43D367B0A4B1" (different from Linux UUIDs)
• contains the NTFS File System
• has a partition UUID of "ca8d0663-6a6e-4b09-a0d7-05b59d109ab1"

and gets mounted on the /media/Data according to this line:

UUID=634E43D367B0A4B1                     /media/Data    ntfs-3g noauto,x-systemd.automount,x-systemd.device-timeout=10,rw,inherit,permissions,streams_interface=windows,windows_names,compression,norecover,hide_dot_files,hide_hid_files,big_writes 0 2

Filesystem Type

This field describes the type of the filesystem. Linux supports many filesystem types: ext4, xfs, btrfs, f2fs, vfat, ntfs-3g (for Windows compatibility), hfsplus (for Mac Compatibility), tmpfs, sysfs, proc, iso9660 (to allow you to mount CD/DVD ISO files as Read-Only directories), udf, squashfs, nfs, cifs, and many more.

An entry swap denotes a file or partition to be used for swapping. An entry none is useful for bind or move mounts.

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

Using the same example fstab file and "Win-Data" line as above, ntfs-3g is the file system we're mounting this one under although the blkid shows ntfs. This is simply because the ntfs driver is a read-only driver (allowing you to see your Windows files, but not modify them, whereas the ntfs-3g (for 3rd generation) allows most NTFS options (except encryption) thus also read-write capabilities:

UUID=634E43D367B0A4B1                     /media/Data    ntfs-3g noauto,x-systemd.automount,x-systemd.device-timeout=10,rw,inherit,permissions,streams_interface=windows,windows_names,compression,norecover,hide_dot_files,hide_hid_files,big_writes 0 2

Mount options

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).

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 (I.E. at boot time)
• user: allow any user to mount (I.E. no sudo needed)
• owner: Only 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.

FAT Mount options

TBD

EXT2/3/4 Mount options

TBD

NTFS-3G Mount options

TBD

Dump?

This field must be 1 or 0 and is used by dump to determine which filesystems need to be dumped in case of a coredump (=crash). Defaults to zero (don’t dump) if not present.

Pass number

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 check the filesystem) if not present.

Tips and tricks

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

user $ man 5 systemd.mount COPY TO CLIPBOARD

for details.

See Also

https://refspecs.linuxfoundation.org/FHS_3.0/index.html