findmnt  will  list  all  mounted  filesytems  or  search  for  a  filesystem.   The  findmnt command is able to search in /etc/fstab, /etc/fstab.d, /etc/mtab or /proc/self/mountinfo.  If device or mountpoint is not given, all filesystems are shown.

 The command prints all mounted filesystems in the tree-like format by default.

Default tree-like output

$ findmnt
TARGET                       SOURCE                       FSTYPE      OPTIONS
/                            /dev/sdb2                    ext4        rw,relatime,barrier=1,data=ordered
├─/proc                      proc                         proc        rw,relatime
│ ├─/proc/bus/usb            /proc/bus/usb                usbfs       rw,relatime
│ └─/proc/sys/fs/binfmt_misc                              binfmt_misc rw,relatime
├─/sys                       sysfs                        sysfs       rw,relatime
├─/dev                       devtmpfs                     devtmpfs    rw,relatime,size=8157124k,nr_inodes=2039281,mode=755
│ ├─/dev/pts                 devpts                       devpts      rw,relatime,gid=5,mode=620,ptmxmode=000
│ └─/dev/shm                 tmpfs                        tmpfs       rw,relatime
├─/boot                      /dev/sdb1                    ext4        rw,relatime,barrier=1,data=ordered
├─/home                      /dev/sdb9                    ext4        rw,relatime,barrier=1,data=ordered
├─/opt                       /dev/sdb6                    ext4        rw,relatime,barrier=1,data=ordered
│ └─/opt/mirror              /etc/auto.mirror             autofs      rw,relatime,fd=6,pgrp=1911,timeout=600,minproto=5,maxproto=5,indirect
├─/tmp                       /dev/sdb8                    ext4        rw,relatime,barrier=1,data=ordered
├─/usr                       /dev/sdb5                    ext4        rw,relatime,barrier=1,data=ordered
├─/var                       /dev/sdb7                    ext4        rw,relatime,barrier=1,data=ordered
│ └─/var/lib/nfs/rpc_pipefs  sunrpc                       rpc_pipefs  rw,relatime
├─/data                      /dev/sdc1                    ext4        rw,relatime,barrier=1,data=ordered
└─/dcsunit07_lun4_5          /dev/mapper/dcsunit07_lun4_5 xfs         rw,relatime,delaylog,sunit=256,swidth=3072,noquota

List mounted file system in /etc/fstab

       -s, --fstab
              Search in /etc/fstab and /etc/fstab.d.  The output is in the list format (see --list).

$ findmnt -s
TARGET            SOURCE                                    FSTYPE OPTIONS
/                 UUID=8e37d096-4494-4a31-80df-e74b6a8c26e3 ext4
/boot             UUID=e10dc5c0-c27a-4617-8945-daab6d597137 ext4
/home             UUID=4442fda3-7149-4f78-b114-ac8820c51549 ext4
/opt              UUID=3166aa04-d05e-4b32-a306-939679882090 ext4
/tmp              UUID=63d12776-b54a-454e-b721-e92526980b3f ext4
/usr              UUID=f2b734b2-2e14-44cd-a1c8-2421b7e4d1b7 ext4
...

List mounted file system in /etc/mtab

       -m, --mtab
              Search in /etc/mtab.  The output is in the list format (see --list).

$ findmnt -m
TARGET                   SOURCE                       FSTYPE      OPTIONS
/                        /dev/sdb2                    ext4        rw
/proc                    proc                         proc        rw
/sys                     sysfs                        sysfs       rw
/dev/pts                 devpts                       devpts      rw,gid=5,mode=620
/dev/shm                 tmpfs                        tmpfs       rw
/boot                    /dev/sdb1                    ext4        rw
/home                    /dev/sdb9                    ext4        rw
...

List mounted file system in /etc/self/mountinfo

       -k, --kernel
              Search in /proc/self/mountinfo.  The output is in the tree-like format.  This is the default.

Example similar to the ones above

List specified file system type

Prints all ext4 file systems currently mounted

$ findmnt -t ext4
TARGET SOURCE    FSTYPE OPTIONS
/      /dev/sdb2 ext4   rw,relatime,barrier=1,data=ordered
/boot  /dev/sdb1 ext4   rw,relatime,barrier=1,data=ordered
...

List swap defined in /etc/fstab

$ findmnt --fstab -t swap
TARGET SOURCE                                    FSTYPE OPTIONS
swap   UUID=8b13596f-3647-4289-b8ab-89ce31719e42 swap

List file systems by mount point

Liste filesystems , currently mounted and defined in fstab

$ findmnt --target /
TARGET SOURCE    FSTYPE OPTIONS
/      /dev/sdb2 ext4   rw,relatime,barrier=1,data=ordered
$ findmnt --fstab /
TARGET SOURCE                                    FSTYPE OPTIONS
/      UUID=8e37d096-4494-4a31-80df-e74b6a8c26e3 ext4

Format output

List /etc/fstab filesystem and converts LABEL= and UUID=tags to the real device names

$  findmnt --fstab --evaluate /boot
TARGET SOURCE    FSTYPE OPTIONS
/boot  /dev/sdb1 ext4

Prints only the mountpoint where the filesystem with label "/data" is mounted

# findmnt -n --raw --evaluate --output=target LABEL=/data
/data