mount -t overlay overlay?

gregors · 06-07-2023, 05:18 PM

Hi there,

I just heard of the 'overlay' type. The man page says the syntax reads

Code:

mount -t overlay overlay -olowerdir= ...

Can anyone tell me why there has to be a second 'overlay'? Well, I know it doesn't work without that. But what does that second 'overlay' trigger?

TIA

Gregor

pan64 · 06-08-2023, 01:04 AM

https://wiki.archlinux.org/title/Overlay_filesystem
https://man7.org/linux/man-pages/man8/mount.8.html

Quote:

The standard form of the mount command is:
mount -t type device dir

gregors · 06-08-2023, 01:39 AM

Quote:

Originally Posted by pan64

https://wiki.archlinux.org/title/Overlay_filesystem
https://man7.org/linux/man-pages/man8/mount.8.html

So, as I understand it, the first 'overlay' is the type of filesystem while the second 'overlay' is some kind of "special device", right? So after mounting (merging) there should be an /dev/overlay device file?

To answer myself: I tried both

Code:

mount -t overlay overlay      -o lowerdir=/tmp:/usr/local/share/:/usr/local/bin/ ./overlay-test/
mount -t overlay overlay-test -o lowerdir=/tmp:/usr/local/share/:/usr/local/bin/ ./overlay-test/

which both resulted in exactly the same 'lowerdir'-directorys being merged in ./overlay-test
So it seems that it doesn't make a difference what the parameter following the '-t overlay' reads.

Hm - I'm confused. Could someone please enlighten me?

Gregor