Date: Tue, 25 Feb 2003 23:51:00 -0800
From: Rick Moen rick@linuxmafia.com
Subject: Re: USB Camera
To: luv@luv.asn.au

Quoting Donovan Craig (donovan@snapfrozen.com):

> Even though the Canon Ixus cameras aren't mass storage devices, you
> still have to mount the USB file system.
>
> Try this as root, it seemed to get my little Ixus talking and working
> with gtkam.
>
> #!/bin/bash
> modprobe usb-uhci
> mount -t usbdevfs usb /proc/bus/usb
>
> see:
>
> http://gphoto.sourceforge.net/doc/manual/permissions-usb.html

That's useful, and links to the even more broadly useful USB Guide,
http://www.linux-usb.org/USB-guide/ .

I've been working with USB on my laptop, since my wife gave me a 32 MB
Easy Disk flash-memory drive, a cute plastic thing on a keychain fob. It
needs the usb-uhci and usb-storage drivers (impliedly also usbcore). At
which point, one can do:

# mount -o uid=1000,gid=1000,noatime -t vfat /dev/sda /mnt/fob/

(where 1000 is my own login account's UID and GID).

Note: That command (or anything like it) always returns:

mount: block device /dev/sda is write-protected, mounting read-only

Two points about that:

(1) I think the automatic read-only mounting default is intended to
protect the device against early failure from wear: Flash memory is
good for about 10,000 write cycles. This is also why I mount using
"noatime": Otherwise, even as routine an operation as "ls" would cause
a write in the form of updating atime (access time).

(2) The Easy Disk appears to be treated like a floppy disk instead of a
hard drive, which is why it's sda instead of sda1. I.e., the block
device it's addressed via cannot be partitioned.

Therefore, attempting "fdisk /dev/sda" returns...

# fdisk /dev/sda
You will not be able to write the partition table.

...because of this device-class consideration (and is the same error
you'd get from attempting "fdisk /dev/fd0").

To enable write access after initial mounting, do:

# mount -o rw,remount /mnt/fob

The mount options cited previously can and should be put in /etc/fstab:
/dev/sda /mnt/fob vfat uid=1000,gid=1000,user,noauto,noatime 0 0

--
Cheers, Founding member of the Hyphenation Society, a grassroots-based,
Rick Moen not-for-profit, locally-owned-and-operated, cooperatively-managed,
rick@linuxmafia.com modern-American-English-usage-improvement association.