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mount and lsblk Disks and mounts

Version util-linux 2.41.5 · source

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Start here

lsblk -f
Disks, filesystems, UUIDs
findmnt
What is mounted where
sudo mount <device> <dir>
Mount a filesystem
sudo mount -o ro <device> <dir>
Mount read-only
sudo umount <dir>
Unmount it
sudo blkid
UUIDs and labels
findmnt --verify
Check fstab for errors
sudo mount -a
Mount everything in fstab

Concepts

  1. Block device /dev/sdb1
  2. Filesystem UUID, label
  3. Mount point /mnt/data
  4. Detached safe to unplug

Discover

lsblk
Tree of block devices
lsblk -f
Add filesystem, label, UUID, mountpoint
lsblk -o NAME,SIZE,TYPE,FSTYPE,MOUNTPOINTS
Pick your own columns
lsblk -p
Show full /dev paths
lsblk -J
JSON output for scripts
sudo blkid
List UUID, label and type of devices
sudo blkid <device>
Probe a single device
findmnt
Tree of mounted filesystems
findmnt <dir>
Which filesystem backs this mount point
findmnt -T <path>
Mount holding any path
findmnt -t ext4,xfs
Only some filesystem types
findmnt --real
Hide pseudo filesystems
findmnt -D
Output like df
findmnt -s
Read fstab instead of live mounts
findmnt -o TARGET,SOURCE,FSTYPE,OPTIONS
Choose columns
mount
List mounts (noisy, includes pseudo)
mount -t <type>
List mounts of one type

Mount and unmount

sudo mount <device> <dir>
Mount, type auto-detected
sudo mount -t <type> <device> <dir>
Force the filesystem type
sudo mount -o <opts> <device> <dir>
Mount with comma-separated options
sudo mount -r <device> <dir>
Mount read-only
sudo mount UUID=<uuid> <dir>
Mount by UUID
sudo mount -L <label> <dir>
Mount by label
sudo mount -m <device> <dir>
Create the mount point first
sudo mount -a
Mount all fstab entries not yet mounted
sudo mount <dir>
Mount using the fstab entry for <dir>
sudo mount -o loop <file.iso> <dir>
Mount an image file
sudo mount -o ro,loop <file.iso> <dir>
Mount an ISO read-only
sudo mount -f -v <device> <dir>
Dry run, verbose
sudo umount <dir>
Unmount by mount point
sudo umount <device>
Unmount by device
sudo umount -l <dir>
Lazy: detach now, clean up later
Use when busy and safe to detach; open files stay usable until closed.
sudo umount -R <dir>
Unmount the whole tree below
sudo umount -f <dir>
Force (mostly for dead NFS)

Bind and remount

sudo mount --bind <dir> <other>
Make a directory visible at a second path
sudo mount --rbind <dir> <other>
Bind including submounts
sudo mount -o remount,ro <dir>
Switch a live mount to read-only
sudo mount -o remount,rw <dir>
Switch a live mount to read-write
sudo mount -o remount,noatime <dir>
Change options without unmounting
sudo mount --bind -o ro <dir> <other>
Read-only view of a directory
Needs util-linux 2.27+; older: bind, then remount,bind,ro.
sudo mount --move <old> <new>
Move a mount point atomically
sudo mount --make-private <dir>
Stop mount event propagation
sudo mount -t tmpfs -o size=<size> tmpfs <dir>
RAM-backed scratch space
sudo mount -t nfs <host>:<export> <dir>
Mount an NFS share
sudo mount -t cifs //<host>/<share> <dir> -o username=<user>
Mount an SMB share
Needs the cifs-utils package.

fstab and options

fstab fields (/etc/fstab)
# Field Example
1 device or UUID= UUID=1a2b-3c4d
2 mount point /data
3 filesystem type ext4
4 options defaults,noatime
5 dump (legacy) 0
6 fsck order 2
A typical fstab line
# device       dir    type  options          dump passUUID=<uuid>    /data  ext4  defaults,noatime  0    2
Common options
Option Effect
defaults rw,suid,dev,exec,auto,nouser,async
ro / rw read-only / read-write
noexec forbid running binaries
nosuid ignore setuid bits
nodev ignore device files
noatime skip access-time writes
nofail do not fail boot if absent
noauto skip on mount -a and boot
user non-root users may mount
x-systemd.automount mount on first access
findmnt --verify
Lint fstab before rebooting
sudo systemctl daemon-reload
Make systemd re-read fstab
findmnt --verify --verbose
Show every check

Recipes

Mount a new USB disk
lsblk -fsudo mkdir -p /mnt/usbsudo mount /dev/sdb1 /mnt/usb# when donesudo umount /mnt/usb
Persist a disk across reboots
lsblk -f                      # note the UUIDsudo mkdir -p /dataecho 'UUID=<uuid> /data ext4 defaults,nofail 0 2' | sudo tee -a /etc/fstabfindmnt --verify && sudo mount -a
Inspect an ISO
sudo mount -o loop,ro image.iso /mntls /mntsudo umount /mnt
Fix a read-only root, then undo
sudo mount -o remount,rw /# edit what you needsudo mount -o remount,ro /