1

I am confused where the devtmpfs filesystem is on my Linux system, I have read on it and I heard it is a virtual filesystem so it should be shown when I run the df -a command it should show the devtmpfs but it doesn't.

Since devtmpfs is a virtual filesystem I thought since it's virtual that's why it's not showing so I thought of searching for the /proc filesystem which is also virtual but /proc is showing. So my question is where is devtmpfs?

Here is my output of df -a :

root@buster10:/dev$ df -a
Filesystem     1K-blocks     Used Available Use% Mounted on
sysfs                  0        0         0    - /sys
proc                   0        0         0    - /proc
udev             1916492        0   1916492   0% /dev
devpts                 0        0         0    - /dev/pts
tmpfs             396232    11448    384784   3% /run
/dev/sda2      955878772 12422396 894830612   2% /
securityfs             0        0         0    - /sys/kernel/security
tmpfs            1981144   123836   1857308   7% /dev/shm
tmpfs               5120        4      5116   1% /run/lock
tmpfs            1981144        0   1981144   0% /sys/fs/cgroup
cgroup2                0        0         0    - /sys/fs/cgroup/unified
cgroup                 0        0         0    - /sys/fs/cgroup/systemd
pstore                 0        0         0    - /sys/fs/pstore
efivarfs               0        0         0    - /sys/firmware/efi/efivars
bpf                    0        0         0    - /sys/fs/bpf
cgroup                 0        0         0    - /sys/fs/cgroup/net_cls,net_prio
cgroup                 0        0         0    - /sys/fs/cgroup/freezer
cgroup                 0        0         0    - /sys/fs/cgroup/cpuset
cgroup                 0        0         0    - /sys/fs/cgroup/devices
cgroup                 0        0         0    - /sys/fs/cgroup/perf_event
cgroup                 0        0         0    - /sys/fs/cgroup/cpu,cpuacct
cgroup                 0        0         0    - /sys/fs/cgroup/memory
cgroup                 0        0         0    - /sys/fs/cgroup/rdma
cgroup                 0        0         0    - /sys/fs/cgroup/pids
cgroup                 0        0         0    - /sys/fs/cgroup/blkio
systemd-1              -        -         -    - /proc/sys/fs/binfmt_misc
mqueue                 0        0         0    - /dev/mqueue
debugfs                0        0         0    - /sys/kernel/debug
hugetlbfs              0        0         0    - /dev/hugepages
/dev/sda1         523248     5220    518028   1% /boot/efi
tmpfs             396228     5876    390352   2% /run/user/1000
fusectl                0        0         0    - /sys/fs/fuse/connections
gvfsd-fuse             0        0         0    - /run/user/1000/gvfs
binfmt_misc            0        0         0    - /proc/sys/fs/binfmt_misc
tracefs                -        -         -    - /sys/kernel/debug/tracing

2

It’s mounted on /dev. To see the file system type, run mount; it should show something like

udev on /dev type devtmpfs (rw,nosuid,relatime,size=16392524k,nr_inodes=4098131,mode=755)

which confirms it’s a devtmpfs.

  • ah i see, thank you my friend for clearing this up for me! but why does it not come up on the df output? – Qasim Nov 1 '19 at 15:26
  • 1
    df shows the mounted device, not the file system type. For virtual file systems the device is often set to match the type (proc, cgroup etc.) but it doesn’t have to be, and /dev ends up mounted in such a way as to show udev rather than devtmpfs. – Stephen Kitt Nov 1 '19 at 15:38

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