Hello,
why there is a listing of pseudo group filesystems
even in stripped down kernel that make suspicious.
wouldn’t basically a plain mounted ext4 file system be enough
Any usefull terminal output to work with?
You can do some neat tricks with /proc, /sys, /dev and many others.
See the kernel command line:
sh@meteor:~> cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-6.18.2-1.0.4.sr20251204-default root=/dev/nvme0n1p3 security= mitigations=auto plymouth.enable=0
See the mounted filesystems:
sh@meteor:~> cat /proc/mounts
/dev/nvme0n1p3 / ext4 rw,relatime 0 0
devtmpfs /dev devtmpfs rw,nosuid,size=7903432k,nr_inodes=1975858,mode=755,inode64 0 0
tmpfs /dev/shm tmpfs rw,nosuid,nodev,inode64 0 0
devpts /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
sysfs /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
See the labels of all filesystems that have one:
sh@meteor:~> ls -l /dev/disk/by-label/
total 0
lrwxrwxrwx 1 root root 15 Dez 24 00:38 efi-boot -> ../../nvme0n1p1
lrwxrwxrwx 1 root root 15 Dez 24 00:38 root-01 -> ../../nvme0n1p3
lrwxrwxrwx 1 root root 15 Dez 24 00:38 root-02 -> ../../nvme0n1p4
lrwxrwxrwx 1 root root 15 Dez 24 00:38 swap -> ../../nvme0n1p2
lrwxrwxrwx 1 root root 15 Dez 24 00:38 work -> ../../nvme0n1p6
…or the UUIDs:
sh@meteor:~> ls -l /dev/disk/by-uuid/
total 0
lrwxrwxrwx 1 root root 15 Dez 24 00:38 1eed3f64-cafc-4977-b8d7-e8ccb6a9857f -> ../../nvme0n1p2
lrwxrwxrwx 1 root root 15 Dez 24 00:38 5969e673-2daa-4904-9d62-8f6d475121d7 -> ../../nvme0n1p4
lrwxrwxrwx 1 root root 15 Dez 24 00:38 771f09d1-0b53-4537-9e0a-3afb40430e3c -> ../../nvme0n1p5
lrwxrwxrwx 1 root root 15 Dez 24 00:38 8f206b58-5422-40cd-b561-d3ee1dd4d110 -> ../../nvme0n1p3
lrwxrwxrwx 1 root root 15 Dez 24 00:38 ba3949fe-98db-4d09-926d-c8ed50e07132 -> ../../nvme0n1p6
lrwxrwxrwx 1 root root 15 Dez 24 00:38 DCEA-F8DD -> ../../nvme0n1p1
See the EFI variables from the NVRAM:
sh@meteor:~> ls -l /sys/firmware/efi/efivars/
...
-rw-r--r-- 1 root root 6 Dez 24 00:38 BootCurrent-8be4df61-93ca-11d2-aa0d-00e098032b8c
-rw-r--r-- 1 root root 8 Dez 24 00:38 BootOptionSupport-8be4df61-93ca-11d2-aa0d-00e098032b8c
-rw-r--r-- 1 root root 24 Dez 24 00:38 BootOrder-8be4df61-93ca-11d2-aa0d-00e098032b8c
-rw-r--r-- 1 root root 46 Dez 24 00:38 BootOrderDefault-0b7646a4-6b44-4332-8588-c8998117f2ef
...
An alias or shell function to see only the “interesting” filesystems with the df command and not all the other ones that are irrelevant for free disk space:
alias df="/bin/df -x tmpfs -x devtmpfs -h -x efivarfs $*
(You can still invoke the original with /bin/df)
Most of those pseudo filesystems are in reality nothing else than kernel tables that are exported for general use. They don’t cost any disk space.
Which ones? The OP did not show anything!
No, but all that cruft in the regular df output annoyed me as well over the years:
sh@meteor:~> /bin/df -Th
Filesystem Type Size Used Avail Use% Mounted on
/dev/nvme0n1p3 ext4 98G 13G 84G 13% /
devtmpfs devtmpfs 7.6G 8.0K 7.6G 1% /dev
tmpfs tmpfs 7.6G 4.0K 7.6G 1% /dev/shm
efivarfs efivarfs 172K 62K 106K 37% /sys/firmware/efi/efivars
tmpfs tmpfs 3.1G 2.1M 3.1G 1% /run
tmpfs tmpfs 1.0M 0 1.0M 0% /run/credentials/systemd-journald.service
tmpfs tmpfs 7.6G 714M 6.9G 10% /tmp
/dev/nvme0n1p4 ext4 98G 2.1M 96G 1% /alternate-root
/dev/nvme0n1p1 vfat 511M 5.8M 506M 2% /boot/efi
/dev/nvme0n1p6 ext4 542G 114G 429G 21% /work
tmpfs tmpfs 1.6G 80K 1.6G 1% /run/user/1000
tmpfs tmpfs 1.0M 0 1.0M 0% /run/credentials/getty@tty1.service
tmpfs tmpfs 1.6G 84K 1.6G 1% /run/user/466
That was when I wondered WTH all that stuff is, and how to get it out of my face. 
One difference, though. The OP is asking about the “mount” command, not “df” … and why we see all the extra entries with “mount” , as with this:
user@machine :~> mount
/dev/nvme0n1p4 on / type btrfs (rw, [ right side snipped ]
devtmpfs on /dev type devtmpfs (rw,
tmpfs on /dev/shm type tmpfs (rw,no
devpts on /dev/pts type devpts (rw,
sysfs on /sys type sysfs (rw,nosuid
securityfs on /sys/kernel/security
cgroup2 on /sys/fs/cgroup type cgro
pstore on /sys/fs/pstore type pstor
efivarfs on /sys/firmware/efi/efiva
bpf on /sys/fs/bpf type bpf (rw,nos
proc on /proc type proc (rw,nosuid,
tmpfs on /run type tmpfs (rw,nosuid
systemd-1 on /proc/sys/fs/binfmt_mi
hugetlbfs on /dev/hugepages type hu
mqueue on /dev/mqueue type mqueue (
debugfs on /sys/kernel/debug type d
tracefs on /sys/kernel/tracing type
fusectl on /sys/fs/fuse/connections
configfs on /sys/kernel/config type
tmpfs on /run/credentials/systemd-t
tmpfs on /run/credentials/systemd-s
tmpfs on /run/credentials/systemd-t
/dev/nvme0n1p4 on /.snapshots type
/dev/nvme0n1p4 on /boot/grub2/i386-
/dev/nvme0n1p4 on /boot/grub2/x86_6
/dev/nvme0n1p4 on /home type btrfs
/dev/nvme0n1p4 on /opt type btrfs (
/dev/nvme0n1p4 on /root type btrfs
/dev/nvme0n1p4 on /srv type btrfs (
/dev/nvme0n1p4 on /tmp type btrfs (
/dev/nvme0n1p4 on /usr/local type b
/dev/nvme0n1p4 on /var type btrfs (
/dev/nvme0n1p3 on /boot/efi type vf
tmpfs on /run/credentials/systemd-t
tmpfs on /run/credentials/systemd-v
tracefs on /sys/kernel/debug/tracin
tmpfs on /run/credentials/getty@tty
tmpfs on /run/user/1000 type tmpfs
portal on /run/user/1000/doc type f
gvfsd-fuse on /run/user/1000/gvfs t
portal on /root/.cache/doc type fus
gvfsd-fuse on /root/.gvfs type fuse
/dev/nvme0n1p1 on /run/media/root/1
user@machine :~>
IMHO “file systems that appear not needed” is the core of the question. And that was what I answered to.
Maybe the OP will give us more details.
Perhaps OP is after a reason behind why I find it logical to do as I do, omit listings of filesystems that exist only in RAM, looking for filesystem status of disk storage space consuming files, rather than mere inode and RAM consumers:
# alias | grep mount
alias Mnt='mount | egrep -v "cgroup|rpc|ramfs|tmpfs|^sys|on /dev|on /proc|on /sys|on /var" | sort '
# Mnt
/dev/md1 on /usr/local type ext4 (rw,noatime)
/dev/md2 on /srv type ext4 (rw,noatime)
/dev/md3 on /home type ext4 (rw,noatime)
/dev/md4 on /data type ext4 (rw,noatime)
/dev/md5 on /bigs type ext4 (rw,noatime)
/dev/nvme0n1p3 on /parts/boot type ext2 (rw,noatime)
/dev/nvme0n1p8 on / type ext4 (rw,noatime)
#