usb0 -> what exactly is it for?

Question

So far, I found out that on GNU/Linux /media/usb0 seems to be a mount point for Ethernet over USB. Nice.

Question: Where is defined, what usb0 is exactly for?

I distilled the above mentioned suspicion from a lot of discussions where usb0is mentioned for Ethernet over USB. But I can't find any definition. Is there a history behind this?

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EDIT: I found the following in FHS 2.3 definitions, section /media:

On systems where more than one device exists for mounting a certain type of media, mount directories can be created by appending a digit to the name of those available above starting with '0', but the unqualified name must also exist.

so the [updated/additional] question: Is usb0 meant for Ethernet over USB or is it just commonly used for this?

Solution

The directory /mnt is a fairly old directory where resources, such as HDDs, are often mounted into the system. They're typically mounted from /etc/fstab, but do not have to be exclusively mounted from there.

If you're wondering where a resource such as /mnt/usb0 is pointing to, or rather what device is "behind" it, you can use the df command to interrogate the situation a little further.

$ cd /mnt/usb0
$ df -h .

Example

Under several Linuxes the directory /media has become a pseudo standard location for mounting USB thumbdrives etc. On my laptop for example when I plug in a USB thumbdrive and cd to it's mounted directory it presents like so:

$ pwd
/media/KINGSTON

$ df -h .
Filesystem            Size  Used Avail Use% Mounted on
/dev/sdb1             7.5G  6.4G  1.2G  86% /media/KINGSTON

You can use the above to try and get a better understanding of the device, if any, that may be behind the mount point /mnt/usb0.

Comments

[user2914606]

are you aware of the UNIX philosophy that everything is a file?

[user2914606]

oh actually, nevermind. misread your question. still, though, I've never seen /mount/usb0 on my boxes. more than that, I've never seen /mount. that directory isn't in the Filesystem Hierarchy Standard, either.

[erch]

@strugee I am, yes. So what, beside the 0, makes the difference between fileand file0? Also: are you aware that one can delete comments if… for whatever reason ;)

[Jeff Hewitt]

Is it possible you mean /mnt/usb0? If that's the case, I don't think it's meant to represent Ethernet over USB specifically. It's a generic mountpoint that can be used to automount removable media over USB. At least that's how things are on my Debian box.

[erch]

@JosephR. MY BAD! Edited /mount to media Thanks for the hint!

[Jeff Hewitt]

@chirp No worries. I make that mistake a lot, too, because I'm used to sounding out the "mount" in my head whenever I think of /mnt (See also /temp mistaken for /tmp :D )

[erch]

MY BAD! SORRY!!! Edited /mount to mnt Thanks for the hint!

[slm]

@chirp - see updates.

[erch]

/media/usb is a softlink to /media/usb0 here (Debian based Crunchbang 10). Seriously, a softlink: Different inodes, differing in just one digit from /media/usb which has the lower inode and /media/usb0 having the exactly next inode available (!).