I was trying to use an USB-stick in Linux and it didn’t go as expected:
I had already created a mountpoint (/mnt), found the device of the newly inserted USB-stick (/dev/sdb1) and mounted it:
# ls -l /dev/sdb1
brw-rw---- 1 root disk 8, 17 Aug 7 16:05 /dev/sdb1
# ls -ld /mnt
drwxrwxrwx 2 root root 4096 Jul 31 2020 /mnt
# mount /dev/sdb1 /mnt
# mount | grep sdb
/dev/sdb1 on /mnt type exfat(rw,relatime,fmask=0022,dmask=0022,iocharset=utf8,errors=remount-ro)
# ls -ld mnt
drwxr-xr-x 2 root root 131072 Aug 7 16:23 mnt
The problem was now that the stick was writable only for root. So I changed the filemode of the directory – which didn’t work at all, although no error was issued:
# chmod -R 777 /mnt
# ls -ld mnt
drwxr-xr-x 2 root root 131072 Aug 7 16:23 mnt
(I also tried “0777” instead of “777” – no difference.) Not being all too familiar with Linux I suspected the problem being that I tried to do something in the root directory. So I created a subdirectory “/mnt/usb1” and repeated above procedure – with the same result. The chmod command came back without an error but the filemode wasn’t changed. As a last resort I tried changing the ownership – which lead to an error (“user” is an existing user/group on this system):
# chown user:user /mnt
chown: changing ownership of '/mnt': Operation not permitted
My system uses kernel 5.15.0-97-generic, if you need more/other information please ask and I will edit it in.
Can someone shed light on what I did wrong? Both commands (chown as well as chmod) are standard UNIX commands and the system I usually work with (AIX) would have done exactly what I intended to do.
As A bonus: if someone could also answer why the chown was “not permitted” I’d be glad.