And it is not just this computer. If I try on my laptop, with only one hard drive:
# ls -l /dev/sd?
brw-rw---- 1 root disk 8, 0 Mar 31 14:26 /dev/sda
brw-rw---- 1 root disk 8, 16 Apr 3 12:12 /dev/sdb
Again, the timestamp for the actual drive (/dev/sda) is when that computer was last booted. And the timestamp for the ghost drive is the time of the “ls” command.
If I plug in a USB drive, that shows as “/dev/sde” and not as “/dev/sdd”. But perhaps that depends on which USB port I plug it into.
This is relatively recent. It used to be that only “/dev/sda”, “/dev/sdb” and “/dev/sdc” showed up (unless I plugged in a USB drive). Something has changed. I’m not sure if it is intentional or a bug.
Is it still there after a reboot? I’ve seen this when I had a USB device mounted and unplugged it when I was still in one of the mountpoint in Yakuake, The /dev/ entry was then not removed. So
mount /dev/sdb1 /mnt
cd /mnt (unplug USB disk )
ls -ltr /dev | tail -4
The last command would still show /dev/sdb and /dev/sdb1 etc. I took tail -4 because I knew the device has 3 partitions.
The listing I gave was after booting (last evening), and before plugging in and USB drives. However, since then I have now plugged in an external drive. My laptop, with similar behavior, has not had any USB drive plugged in for several weeks. It does have a USB mouse. I tried unplugging that, but nothing changes (other than the mouse change). I have not tried rebooting without the USB mouse.
My main desktop (for the original listing that I gave) routinely has a USB mouse, a USB keyboard and a USB ups system connected, none of which are disks or disk-like.
No. It is next unused SCSI disk name. It does not matter how it is connected. What “lsusb -t” says? Full “udevadm info --export-db” output would be even better.
I am not affluent with Udev, but as udev creates the device files, checking there might be helpful. I know udev has some informational commands and/or loggings.
I can upload the current “dmesg” output. If you need me to reboot first, then I’ll delay until a convenient time. My next scheduled reboot is Monday morning, but I guess I can do an earlier one.
@nrickert has a disk that he can not identify, because there is only one disk present on his system.
To show you have the same or similar astonishment, you should at least explain which of thoses devices do not correspond to a disk you physicaly have, else it is just a list of your mass-storage devices.
Please re-read and try to understand what df does
man df
The command you gave lets df first search for the file /dev/sdd. Then it finds out on what file system that file sits. That file system happens to be /dev. Then it shows data about that file system. Amongst that is what device it is mounted from (/dev) and the file system type (devtmpfs).
That will be true for all /dev/sd? files you try. Even for /dev/sda, /dev/sdb and /dev/sdc.
It is in fact the first line of what you see on my system when I use no file name, which then means
If no file name is given, the space available on all currently mounted file systems is shown
I will get that first line for every file I give to df that is inside the /dev mount point:
henk@boven:~> df /dev/sda
Filesystem 1K-blocks Used Available Use% Mounted on
devtmpfs 4001520 8 4001512 1% /dev
henk@boven:~> df/dev/sdb
bash: df/dev/sdb: Bestand of map bestaat niet
henk@boven:~> df /dev/sdb
Filesystem 1K-blocks Used Available Use% Mounted on
devtmpfs 4001520 8 4001512 1% /dev
henk@boven:~> df /dev/tty
Filesystem 1K-blocks Used Available Use% Mounted on
devtmpfs 4001520 8 4001512 1% /dev
henk@boven:~>
Like I will always get the information about the file system mounted on /home with
henk@boven:~> df /home/henk
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda4 206291640 84842612 120384080 42% /home
henk@boven:~> df /home/henk/bin
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda4 206291640 84842612 120384080 42% /home
henk@boven:~>
