Is there a command to see where a disk is mounted?

Is there a simple command that takes a disk’s device node as input, and tells me where (and whether) that disk is mounted? Is it possible to get the mount point by itself, so I can pass it to another command?

I’m working on a Debian Squeeze live system with a minimal install (I can install extra packages if need be).

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

On Linux, you can now use the findmnt command from util-linux (since version 2.18):

$ findmnt -S /dev/VG_SC/home
TARGET SOURCE                 FSTYPE OPTIONS
/home  /dev/mapper/VG_SC-home ext4   rw,relatime,errors=remount-ro,data=ordered

Or lsblk (also from util-linux, since 2.19):

$ lsblk /dev/VG_SC/home
NAME       MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
VG_SC-home 254:2    0  200G  0 lvm  /home

That one is also useful to find all the file system mounted under a specific device (disk or partition…):

$ lsblk  /dev/sda2
NAME                    MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda2                      8:2    0  59.5G  0 part
├─linux-debian64 (dm-1) 252:1    0    15G  0 lvm
└─linux-mint (dm-2)     252:2    0    15G  0 lvm  /

To get the mountpoint only:

$ findmnt -nr -o target -S /dev/storage/home
/home
$ lsblk -o MOUNTPOINT -nr /dev/storage/home
/home

Above findmnt does return with a failure exit status if the device is not mounted, not lsblk.

So:

if mountpoint=$(findmnt -nr -o target -S "$device"); then
  printf '"%s" is mounted on "%s"n' "$device" "$mountpoint"
else
  printf '"%s" does not appear to be directly mountedn' "$device"
fi

Method 2

Under Linux, you can get mount point information directly from the kernel in /proc/mounts. The mount program records similar information in /etc/mtab. The paths and options may be different, as /etc/mtab represents what mount passed to the kernel whereas /proc/mounts shows the data as seen inside the kernel. /proc/mounts is always up-to-date whereas /etc/mtab might not be if /etc was read-only at some point that wasn’t expected by the boot scripts. The format is similar to /etc/fstab.

In both files, the first whitespace-separated field contains the device path and the second field contains the mount point.

awk -v needle="$device_path" '$1==needle {print $2}' /proc/mounts

or if you don’t have awk:

grep "^$device_path " /proc/mounts | cut -d ' ' -f 2

There are a number of edge cases where you might not get what you expect. If the device was mounted via a different path in /dev that designates the same device, you won’t notice it this way. In /proc/mounts, bind mounts are indistinguishable from the original. There may be more than one match if a mount point shadows another (this is unusual).

In /proc/self or /proc/$pid, there is a per-process mounts file that mimics the global file. The mount information may vary between processes, for example due to chroot. There is an additional file called mountinfo that has a different format and includes more information, in particular the device major and minor numbers. From the documentation:

36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
(1)(2)(3)   (4)   (5)      (6)      (7)   (8) (9)   (10)         (11)

(1) mount ID:  unique identifier of the mount (may be reused after umount)
(2) parent ID:  ID of parent (or of self for the top of the mount tree)
(3) major:minor:  value of st_dev for files on filesystem
(4) root:  root of the mount within the filesystem
(5) mount point:  mount point relative to the process's root
(6) mount options:  per mount options
(7) optional fields:  zero or more fields of the form "tag[:value]"
(8) separator:  marks the end of the optional fields
(9) filesystem type:  name of filesystem of the form "type[.subtype]"
(10) mount source:  filesystem specific information or "none"
(11) super options:  per super block options

So if you’re looking for a device by number, you can do it like this:

awk -v dev="$major:minor" '$3==dev {print $5}'
awk -v dev="$(stat -L -c %t:%T /dev/block/something)" '$3==dev {print $5}'

Method 3

The mount command with no arguments will list all currently mounted filesystems; you can grep that for the disk you want (or grep /etc/mtab, which is the file mount reads the information from):

$ grep /dev/sda /etc/mtab
/dev/sda3 /boot ext2 rw,noatime 0 0

Method 4

Yes. You can see Showing Only Interesting Mount Points/Filtering Non-Interesting Types or Listing Directories under / that are Not Under the Same Mountpoint for some example usage, but there’s also a brief rundown below. The command you are asking about is findmnt (though lsblk might also serve):

lsblk -f /dev/sda[12]

NAME FSTYPE LABEL UUID                                 MOUNTPOINT
sda1 vfat   ESP   F0B7-5DAE                            /esp
sda2 btrfs  sys   94749918-bde1-46e6-b77c-b66e0368ecdb /    

Now, as you can see, /dev/sda1 is mounted on /esp. I wonder if it is mounted elsewhere as well?

findmnt /dev/sda1

TARGET SOURCE                    FSTYPE OPTIONS
/esp   /dev/sda1                 vfat   rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro
/boot  /dev/sda1[/EFI/arch_root] vfat   rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro

Aha. I see. A subfolder is also --bind mounted over boot. Ok…

sudo umount /boot /esp
findmnt /dev/sda1

Nothing. What the hell?

echo "$?"

1

Ohhh… Well, that’s nice. Hmmm…

for d in 1 2
do    findmnt "/dev/sda$d" >/dev/null
      printf  "/dev/sda$d%.$((6>>!$?))s%sn"
              " isn't" " currently mounted."
done

/dev/sda1 isn't currently mounted.
/dev/sda2 is currently mounted.

Oh, yeah, that’s really nice.

for d in /dev/sd*
do    findmnt -noSOURCE,TARGET "$d"
done

/dev/sda2[/arch_root] /

Now let’s put sda1 back where it belongs and try that again…

sudo mount -a
for d in /dev/sd*
do    findmnt -noSOURCE,TARGET "$d"
done

/dev/sda1                 /esp
/dev/sda1[/EFI/arch_root] /boot
/dev/sda2[/arch_root] /

But where did I find this magical command?

man mount | sed -e:n -e'/findmnt/!d;N;/n$/q;bn'

For more robust and customizable output use findmnt(8), especially in your scripts. Note that control characters in the mountpoint name are replaced with ?.

Method 5

I don’t know of a clean and simple way to detect whether or not a device node in /dev is mounted. This is what I can offer, though. It handles directly mounted devices (/dev/sda1) and devices mounted by UUID (/dev/disk/by-uuid/aa4e7b08-6547-4b5a-85ad-094e9e1af74f). It breaks if your device names contain whitespace.

deviceIsMounted()
{
    local DEVICE="$1"
    local MOUNT=$(
        (
            echo "$DEVICE"
            find /dev -type l -lname "*${DEVICE/*/}" -exec readlink -f {} ; -print |
                xargs -n2 |
                awk -v device="$DEVICE" '$1 == device {print $2}'
        ) |
            xargs -n1 -i{} grep -F {} /proc/mounts
    )
    test -n "$MOUNT" && echo "$MOUNT"
}

deviceIsMounted /dev/sda1 && echo yes              # Mountpoint and status
deviceIsMounted /dev/md2 >/dev/null && echo yes    # Just status

The function writes the entry from /proc/mounts to stdout if found, also setting exit status to 0. Otherwise the exit status is 1.

Method 6

Just run the below command:

df -h

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0