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A(z) fstab(5) fájl segítségével meghatározható, hogy a lemezpartíciók, kül?nféle egyéb blokkadathordozók, távoli fájlrendszerek hogyan legyenek felcsatolva a fájlrendszerünkbe.
Minden fájlrendszert kül?n sorban írunk le. Ezek a definíciók dinamikusan konvertálódnak systemd csatolási egységekké a bootoláskor, valamint a system manager beállításának újrat?ltésekor. Az alapértelmezett beállítás automatikusan ellen?rzi (fsck) és csatolja a fájlrendszereket, miel?tt elindulnának azok a szolgáltatások amelyekhez el?feltétel a felcsatolt állapot. Például a systemd automatikusan gondoskodik arról, hogy a távoli fájlrendszerek csatolásai, mint például az NFS vagy a Samba, csak a hálózat beállítása után induljanak el. Ezért a /etc/fstab fájlban megadott helyi és távoli fájlrendszer-csatolásoknak azonnal m?k?dniük kell. Részletekért tekintse meg a systemd.mount(5) fájlt.
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.
Használat
A simple /etc/fstab, using file system UUIDs:
/etc/fstab
# <device> <dir> <type> <options> <dump> <fsck>
UUID=0a3407de-014b-458b-b5c1-848e92a327a3 / ext4 defaults 0 1
UUID=CBB6-24F2 /boot vfat defaults,nodev,nosuid,noexec,fmask=0177,dmask=0077 0 2
UUID=f9fe0b69-a280-415d-a03a-a32752370dee none swap defaults 0 0
UUID=b411dc99-f0a0-4c87-9e05-184977be8539 /home ext4 defaults 0 2
<device>describes the block special device or remote file system to be mounted; see #Identifying file systems.<dir>is the directory where the file system will be mounted to, aka the mountpoint. The directory must be created beforehand.<type>is the file system type.<options>are the file system mount options; see mount(8) § FILESYSTEM-INDEPENDENT MOUNT OPTIONS and ext4(5) § Mount options for ext4.<dump>is checked by the dump(8) utility. This field is usually set to0, which disables the check.<fsck>sets the order for file system checks at boot time; see fsck(8). For the root device it should be1. For other partitions it should be2, or0to disable checking.
- The
autotype lets the mount command guess what type of file system is used. This is useful for optical media (CD/DVD/Blu-ray). - If the root file system is btrfs or XFS, the fsck order should be set to
0instead of1. See fsck.btrfs(8) and fsck.xfs(8).
All specified devices within /etc/fstab will be automatically mounted on startup and when the -a flag is used with mount(8) unless the noauto option is specified. Devices that are listed and not present will result in an error unless the nofail option is used.
See fstab(5) § DESCRIPTION for details.
Identifying file systems
There are different ways to identify file systems that will be mounted in /etc/fstab: kernel name descriptor, file system label and UUID, and GPT partition label and UUID for GPT disks. Kernel name descriptors should not be used, while UUIDs or PARTUUIDs should be preferred over 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 file systems 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.
Kernel name descriptors
Run lsblk -f to list the partitions and prefix the values in the NAME column with /dev/.
/etc/fstab
# <device <dir> <type> <options> <dump> <fsck>
/dev/sda2 / ext4 defaults 0 1
/dev/sda1 /boot vfat defaults,nodev,nosuid,noexec,fmask=0177,dmask=0077 0 2
/dev/sda3 /home ext4 defaults 0 2
/dev/sda4 none swap defaults 0 0
/etc/fstab).File system labels
Run lsblk -f to list the partitions, and prefix the values in the LABEL column with LABEL= or alternatively run blkid and use the LABEL values without the quotes:
/etc/fstab
# <device> <dir> <type> <options> <dump> <fsck>
LABEL=System / ext4 defaults 0 1
LABEL=ESP /boot vfat defaults,nodev,nosuid,noexec,fmask=0177,dmask=0077 0 2
LABEL=Data /home ext4 defaults 0 2
LABEL=Swap none swap defaults 0 0
File system UUIDs
Run lsblk -f to list the partitions, and prefix the values in the UUID column with UUID= or alternatively run blkid and use the UUID values without the quotes:
/etc/fstab
# <device> <dir> <type> <options> <dump> <fsck>
UUID=0a3407de-014b-458b-b5c1-848e92a327a3 / ext4 defaults 0 1
UUID=CBB6-24F2 /boot vfat defaults,nodev,nosuid,noexec,fmask=0177,dmask=0077 0 2
UUID=b411dc99-f0a0-4c87-9e05-184977be8539 /home ext4 defaults 0 2
UUID=f9fe0b69-a280-415d-a03a-a32752370dee none swap defaults 0 0
GPT partition labels
Run blkid to list the partitions, and use the PARTLABEL values without the quotes:
/etc/fstab
# <device> <dir> <type> <options> <dump> <fsck>
PARTLABEL=GNU/Linux / ext4 defaults 0 1
PARTLABEL=EFI\040system\040partition /boot vfat defaults,nodev,nosuid,noexec,fmask=0177,dmask=0077 0 2
PARTLABEL=Home /home ext4 defaults 0 2
PARTLABEL=Swap none swap defaults 0 0
GPT partition UUIDs
Run blkid to list the partitions, and use the PARTUUID values without the quotes:
/etc/fstab
# <device> <dir> <type> <options> <dump> <fsck>
PARTUUID=98a81274-10f7-40db-872a-03df048df366 / ext4 defaults 0 1
PARTUUID=d0d0d110-0a71-4ed6-936a-304969ea36af /boot vfat defaults,nodev,nosuid,noexec,fmask=0177,dmask=0077 0 2
PARTUUID=7280201c-fc5d-40f2-a9b2-466611d3d49e /home ext4 defaults 0 2
PARTUUID=039b6c1c-7553-4455-9537-1befbc9fbc5b none swap defaults 0 0
Tips and tricks
Automount with systemd
See systemd.mount(5) for all systemd mount options.
Local partition
In case of a large partition, it may be more efficient to allow services that do not depend on it to start while it is checked by fsck. This can be achieved by adding the following options to the /etc/fstab entry of the partition:
x-systemd.automount
This will fsck and mount the partition only when it is first accessed, and the kernel will buffer all file access to it until it is ready.
This method can be relevant if one has, for example, a significantly large /home partition.
autofs which is ignored by locate by default.Remote file system
The same applies to remote file system mounts. If you want them to be mounted only upon access, you will need to use the x-systemd.automount parameters. In addition, you can use the x-systemd.mount-timeout= option to specify how long systemd should wait for the mount command to finish. Also, the _netdev option ensures systemd understands that the mount is network dependent and order it after the network is online.
x-systemd.automount,x-systemd.mount-timeout=30,_netdev
Encrypted file system
If you have secondary encrypted file systems with keyfiles, you can also add the nofail parameter to the corresponding entries in /etc/crypttab and /etc/fstab. systemd will not wait for the cryptsetup service to finish unlocking and mounting the filesystem on boot, but instead may finish mounting this after reaching default.target. This will avoid any boot delay caused by unlocking secondary partitions that are not required immediately after boot. See dm-crypt/System configuration#Non blocking mounting for cryptsetup configuration
Since mount services will by default only wait for 90 seconds for the partition to be available, any delay in making the keyfile available may cause the mount to fail. To avoid this, add the option x-systemd.mount-timeout=0 to fstab in order to make sure that the mount service waits indefinitely for the partition to be unlocked.
/etc/fstab
UUID=0a3407de-014b-458b-b5c1-848e92a327a3 /data ext4 defaults,nofail,x-systemd.device-timeout=0 0 2
Automatic unmount
You may also specify an idle timeout for a mount with the x-systemd.idle-timeout flag. For example:
x-systemd.automount,x-systemd.idle-timeout=1min
This will make systemd unmount the mount after it has been idle for 1 minute.
External devices
External devices that are to be mounted when present but ignored if absent may require the nofail option. This prevents errors being reported at boot. For example:
/etc/fstab
LABEL=MyExternalDrive /media/backup jfs nofail,x-systemd.device-timeout=5 0 2
The nofail option is best combined with the x-systemd.device-timeout option. This is because the default device timeout is 90 seconds, so a disconnected external device with only nofail will make your boot take 90 seconds longer, unless you reconfigure the timeout as shown. Make sure not to set the timeout to 0, as this translates to infinite timeout.
Filepath spaces
Since spaces are used in fstab 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 0 0 LABEL=Storage\040drive /media/100\040GB\040(Storage) ext4 defaults,user 0 2
atime options
Below atime options can impact drive performance.
- The
strictatimeoption updates the access time of the files every time they are accessed. This is more purposeful when Linux is used for servers; it does not have much value for desktop use. The drawback about thestrictatimeoption is that even reading a file from the page cache (reading from memory instead of the drive) will still result in a write. - The
noatimeoption fully disables writing file access times to the drive every time you read a file. This works well for almost all applications, except for those that need to know if a file has been read since the last time it was modified. The write time information to a file will continue to be updated anytime the file is written to with this option enabled. - The
nodiratimeoption disables the writing of file access times only for directories while other files still get access times written. relatimeupdates the access time only if the previous access time was earlier than the current modify or change time. In addition, since Linux 2.6.30, the access time is always updated if the previous access time was more than 24 hours old. This option is used when thedefaultsoption,atimeoption (which means to use the kernel default, which isrelatime; see mount(8) and Once upon atime) or no options at all are specified.
When using Mutt or other applications that need to know if a file has been read since the last time it was modified, the noatime option should not be used; using the relatime option is acceptable and still provides a performance improvement.
Since kernel 4.0 there is another related option:
lazytimereduces writes to disk by maintaining changes to inode timestamps (access, modification and creation times) only in memory. The on-disk timestamps are updated only when either (1) the file inode needs to be updated for some change unrelated to file timestamps, (2) a sync to disk occurs, (3) an undeleted inode is evicted from memory or (4) if more than 24 hours passed since the last time the in-memory copy was written to disk.
- Warning In the event of a system crash, the access and modification times on disk might be out of date by up to 24 hours.
Note that the lazytime option works in combination with the aforementioned *atime options, not as an alternative. That is relatime by default, but can be even strictatime with the same or less cost of disk writes as the plain relatime option.
Remounting the root partition
If for some reason the root partition has been improperly mounted read only, remount the root partition with read-write access with the following command:
# mount -o remount,rw /
GPT partition automounting
When using UEFI/GPT, it is possible to omit certain partitions from /etc/fstab by partitioning according to the Discoverable Partitions Specification and have systemd-gpt-auto-generator(8) mount the partitions. See systemd#GPT partition automounting.
To specify custom mount options for the root volume, use /dev/gpt-auto-root as the device name:
/etc/fstab
/dev/gpt-auto-root / ext4 defaults,noatime 0 1
Bind mount
You can link directories with the bind option:
/etc/fstab
# <device> <dir> <type> <options> <dump> <fsck> UUID=94649E22649E06E0 /media/user/OS/ ntfs defaults,rw,errors=remount-ro 0 0 /media/user/OS/Users/user/Music/ /home/user/Music/ none defaults,bind 0 0 /media/user/OS/Users/user/Pictures/ /home/user/Pictures/ none defaults,bind 0 0 /media/user/OS/Users/user/Videos/ /home/user/Videos/ none defaults,bind 0 0 /media/user/OS/Users/user/Downloads/ /home/user/Downloads/ none defaults,bind 0 0 /media/user/OS/Users/user/Documents/ /home/user/Documents/ none defaults,bind 0 0 /media/user/OS/Users/user/projects/ /home/user/projects/windows/ none defaults,bind 0 0
See mount(8) § Bind mount operation for details.
Automatically generate an fstab using genfstab
You can use the genfstab tool to create an fstab file. See genfstab for details.
GUI utilities
Here is a list of programs that can be used to modify mount points. They might not have all the features possible for editing fstab, but have all of the most used ones and might make your workflow much easier:
- GNOME Disks — A GNOME utility for dealing with storage devices. Part of gnome.
- KDE Partition Manager — Utility to help you manage the disks, partitions, and file systems on your computer. Part of kde-system.
Modifying user permissions and ownership
If you want to allow any user to mount the drive, consider adding these mount options to add onto your fstab entries.
users- Allow any user to mount and to unmount the filesystem, even when some other ordinary user mounted it. This option implies the options noexec, nosuid, and nodev (unless overridden by subsequent options, as in the option line users,exec,dev,suid). Simply addusersto the mount options to enable this.user- Allow an ordinary user to mount the filesystem. Only allows the same user to unmount. This option implies the options noexec, nosuid, and nodev (unless overridden by subsequent options, as in the option line user,exec,dev,suid). Simply adduserto the mount options to enable this.
For filesystems that do not have file permissions built in such as FAT and exFAT, you can explicitly set the user or group for the entire drive and its files. You can view the ID of a specific user in /etc/passwd. The uid is the third number in the entry, and the group id is the fourth.
uid- Set the owner ID of the drivegid- Set the group ID of the drive
For ext4, btrfs, and other filesystems that have permission abilities, other users might not be permitted to see the drive. Be sure to double check the permissions of /path/to/drive/ and modify them for what you need.
Verify changes
Use findmnt --verify --verbose to check for syntax errors and invalid options in fstab.