Greetings To The GTALUG Community:

I'm trying to discover where an overlay filesystem is mapped, for a Debian live boot from a USB stick.

After perusing a dog's breakfast of output from various linux commands, I am appealing to GTALUG members for guidance.

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I boot live Debian 11 linux from a USB memory stick.

This provides an overlay filesystem:
...
user@debian:~$ df -h
Filesystem      Size  Used Avail Use% Mounted on
udev            7.8G     0  7.8G   0% /dev
tmpfs           1.6G  1.6M  1.6G   1% /run
/dev/sdb1       3.5G  3.5G     0 100% /run/live/medium
/dev/loop0      2.9G  2.9G     0 100% /run/live/rootfs/filesystem.squashfs
tmpfs           7.8G  1.6G  6.3G  20% /run/live/overlay
overlay         7.8G  1.6G  6.3G  20% /
tmpfs           7.8G     0  7.8G   0% /dev/shm
tmpfs           5.0M  4.0K  5.0M   1% /run/lock
tmpfs           7.8G  8.0K  7.8G   1% /tmp
tmpfs           1.6G  1.7M  1.6G   1% /run/user/1000
/dev/sdc1        59G  1.7G   57G   3% /media/user/245B-74A8
/dev/sda2       1.8T  767G  958G  45% /media/user/32ec11e8-082c-4ca5-b751-dc2852f9d5e2
user@debian:~$ 
...

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I believe that the overlay filesystem provides the root directory for linux.

Files under GNOME shows under Other Locations > Computer a root directory:
...
user@debian:/$ ls -aAl
total 0
lrwxrwxrwx   1 root root    7 Dec 17  2022 bin -> usr/bin
drwxr-xr-x   2 root root  144 Dec 17  2022 boot
drwxr-xr-x  18 root root 3580 Mar 20 17:58 dev
drwxr-xr-x   1 root root  640 Mar 20 14:32 etc
drwxr-xr-x   1 root root   60 Mar 20 08:14 home
lrwxrwxrwx   1 root root   31 Dec 17  2022 initrd.img -> boot/initrd.img-5.10.0-20-amd64
lrwxrwxrwx   1 root root   31 Dec 17  2022 initrd.img.old -> boot/initrd.img-5.10.0-20-amd64
lrwxrwxrwx   1 root root    7 Dec 17  2022 lib -> usr/lib
lrwxrwxrwx   1 root root    9 Dec 17  2022 lib32 -> usr/lib32
lrwxrwxrwx   1 root root    9 Dec 17  2022 lib64 -> usr/lib64
lrwxrwxrwx   1 root root   10 Dec 17  2022 libx32 -> usr/libx32
drwxr-xr-x   1 root root   60 Mar 20 08:17 media
drwxr-xr-x   2 root root    3 Dec 17  2022 mnt
drwxr-xr-x   2 root root    3 Dec 17  2022 opt
dr-xr-xr-x 266 root root    0 Mar 20 08:14 proc
drwx------   1 root root   60 Dec 17  2022 root
drwxr-xr-x  31 root root  800 Mar 20 08:17 run
lrwxrwxrwx   1 root root    8 Dec 17  2022 sbin -> usr/sbin
drwxr-xr-x   2 root root    3 Dec 17  2022 srv
dr-xr-xr-x  13 root root    0 Mar 20 08:14 sys
drwxrwxrwt  17 root root  400 Mar 20 18:49 tmp
drwxr-xr-x   1 root root   80 Dec 17  2022 usr
drwxr-xr-x   1 root root  140 Dec 17  2022 var
lrwxrwxrwx   1 root root   28 Dec 17  2022 vmlinuz -> boot/vmlinuz-5.10.0-20-amd64
lrwxrwxrwx   1 root root   28 Dec 17  2022 vmlinuz.old -> boot/vmlinuz-5.10.0-20-amd64
user@debian:/$
...

When I right-click on the word Computer in the title bar of the Files window, and select Properties, it shows:
...
Name      /
Type        Folder (inode/directory)
Contents 297,003 items, totaling 10.9 GB
               (some contents unreadable)

The space allocation graphic shows:
   1.7 GB used
   6.7 GB available
 Filesystem type  overlay

Open in Disks
...

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I have tried using many linux commands to find out where the overlay filesystem is mapped:
...
df -h

ls -l /dev/disk/by-id

gdisk (/dev/sda)
gdisk (/dev/sdb)
gdisk (/dev/sdc)

cfdisk /dev/sda
cfdisk /dev/sda
cfdisk /dev/sdc

sfdisk -J /dev/sda
sfdisk -J /dev/sdb
sfdisk -J /dev/sdc

user@debian:/$ cd /dev
user@debian:/dev$ ls -aAl

sfdisk -T --label (dos, gpt)

blkid

lsblk

lsblk

parted -l

mount

sgdisk
...

Output from all these commands is in the attached text file:

ASP -- commands - looking for overlay filesystem device - 20240320.txt

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Suggestions from GTALUG members would be greatly appreciated !!

Steve Petrie

Etobicoke (Toronto), Ontario, Canada

apetrie@aspetrie.net
416-233-6116