Using a USB flash drive with Linux by wgl47616


									Using a USB flash drive with Linux
September 8, 2003
By: Dave Salvator

USB Flash drives are one of the coolest new tools available these days. And they're getting so cheap,
it's easy to carry one around with you anywhere. Finally it looks like the USB flash drive will kill off the
floppy once and for all – except for the lack of native Linux support.
I carry my files back and forth from the office to home with a 32MB USB flash drive. But transporting
files from my Linux test machine at work typically involves two steps:
     1. Copy the bits onto a Windows machine via Samba
     2. Write those bits to my USB flash drive using the Wintel machine.
Now this is not really an arduous process, but wouldn't it be nice to use that flash drive directly in the
Linux system? Well I recently figured out how to do that, and I thought I'd share my experience with
This tip was put together on a box running Red Hat 9, but the same procedure should yield the same
results on any Linux distro.

Getting Started
To start off, you'll need to be logged in as root to set this up and to set permissions.
Verify that you have the needed kernel modules loaded. To find out what modules you have loaded,
open a terminal window and type the following:
    lsmod | more
The output of lsmod will look like this:

    Module Size Used by Not tainted
    nls_cp437 5116 0 (autoclean)
    vfat 13004 0 (autoclean)
    fat 38808 0 (autoclean) [vfat]
    nls_iso8859-1 3516 0 (autoclean)
    udf 98400 0 (autoclean)
    ide-scsi 12208 0
    soundcore 6404 6 (autoclean) [snd]
    sd_mod 13516 0 (autoclean)
    lp 8996 0 (autoclean)
    parport 37056 0 (autoclean) [lp]
    autofs 13268 0 (autoclean) (unused)
    e100 60644 1
    ipt_REJECT 3928 6 (autoclean)
    iptable_filter 2412 1 (autoclean)
    ip_tables 15096 2 [ipt_REJECT iptable_filter]
    sg 36524 0 (autoclean)
    sr_mod 18136 0 (autoclean)
    scsi_mod 107160 4 [ide-scsi sd_mod sg sr_mod]
    ide-cd 35708 0
    cdrom 33728 0 [sr_mod ide-cd]
    keybdev 2944 0 (unused)
    mousedev 5492 1
    hid 22148 0 (unused)
    input 5856 0 [keybdev mousedev hid]
    usb-uhci 26348 0 (unused)
    usbcore 78784 1 [hid usb-uhci]
    ext3 70784 2
    jbd 51892 2 [ext3]

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By default, Red Hat loads usb-uhci and usbcore on startup. But you'll need to load an additional
module called usb-storage in order to get a flash drive working. To do this, simply type:
    modprobe usb-storage
Next, we'll need to define a mount point for the USB flash drive, which includes a directory for the
mount point. So go to the /mnt sub-directory and create this sub-directory.
    cd /mnt
    mkdir /usbstick
Now we need to edit a file called fstab, which lives in the /etc directory. This file defines storage
devices and the location of their mount-points.
Open the file using gedit, emacs or your text editor of choice. Its contents will look like this:

    LABEL=/ / ext3 defaults 1 1
    LABEL=/boot /boot ext3 defaults 1 2
    none /dev/pts devpts gid=5,mode=620 0 0
    none /proc proc defaults 0 0
    none /dev/shm tmpfs defaults 0 0
    /dev/hda3 swap swap defaults 0 0
    /dev/cdrom /mnt/cdrom udf,iso9660 noauto,owner,kudzu,ro 0 0
    /dev/fd0 /mnt/floppy auto noauto,owner,kudzu 0 0
We need to add a line to this file that reads:
    /dev/sda1 /mnt/usbstick vfat user,noauto,umask=0 0 0
You can copy/paste the above line directly into your fstab file.
The "sda1" represents the device name that the kernel gives the USB flash drive when it gets
plugged in.
Once you've added this line to the fstab file, save it and close your text editor.
Now we're almost ready to plug in your USB flash drive. Open a second terminal window and type:
    tail -s 3 -f /var/log/messages
This command will poll the kernel's message log every three seconds, and displays the latest
messages the kernel has spat out. This is a useful debug tool to make sure the USB flash drive has
been enumerated, and assigned a device name. Generally, the device name will be:
Now, go ahead and plug your flash drive into the USB port.

Up and Running
Once you've plugged the drive in, look at the terminal window where you're monitoring the kernel's
event messages and verify that it has enumerated the USB device. You should see something like
    Aug 26 17:06:09 localhost kernel: hub.c: new USB device 00:1f.2-1, assigned address
    Aug 26 17:06:13 localhost /etc/hotplug/usb.agent: Setup usb-storage for USB product
    Aug 26 17:06:13 localhost /etc/hotplug/usb.agent: Setup nomadjukebox for USB
    product d7d/100/100
    Aug 26 17:06:13 localhost /etc/hotplug/usb.agent: Module setup nomadjukebox for USB
    product d7d/100/100
    Aug 26 17:06:13 localhost kernel: SCSI device sda: 121856 512-byte hdwr sectors (62
    MB) Aug 26 17:06:13 localhost kernel: sda: Write Protect is off
    Aug 26 17:06:13 localhost kernel: sda: sda1 Aug 26 17:06:13 localhost devlabel:
    devlabel service started/restarted

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The key event here is that the device was assigned as /dev/sda1. You can now mount the volume by
    cd /mnt
    mount usbstick
If all has gone well, a disk icon will appear on your KDE/Gnome desktop and double-clicking on it will
open a window that reveals the contents of your USB flash drive.
There's also a way to automate this process, where you can mount your USB flash drive without
having to type anything at a command line. In Gnome, when you right-click anywhere on the desktop,
one of the menu choices you have is Scripts, which is a quick and easy way to execute Bash scripts
without having to open a terminal window. By default, there are no scripts in the folder that this menu
points to, but there is an option to open that folder. Once in the folder, create a new text file and open
it in your favorite text editor (we use gedit) to write the following script.
You can simply copy/paste what we have here into your Bash script:

    modprobe usb-storage
    cd /mnt
    mount usbstick
We run the modprobe command just to make sure that the usb-storage module is loaded. If it's
already loaded, there's no harm done, and if it wasn't already loaded, now it is.
Now save the script as something like mount usbstick, and copy it into the
/root/.gnome2/nautilus-scripts sub-directory.
From Gnome/KDE, right-click on this script and go to the Permissions tab dialog. Set the script as
executable by the appropriate groups/users, and click OK.
You'll want this script to be available to non-root users, so be sure to copy it to their respective sub-
Now when you right-click on the desktop and go down to the Scripts menu choice, in the Scripts sub-
menu you should see your mount usbstick script.
If you have your USB flash drive mounted as a volume, right-click on it, and the bottom menu choice
should be Unmount Volume. Go ahead and unmount the volume and physically remove the USB
flash drive.
Now go ahead and re-insert the flash drive into an available USB port. Next, right-click on the
desktop, go into the Scripts sub-menu and execute your mount usbstick script. The drive icon for
your flash drive should appear on your desktop, and you're ready to pull bits off of it or write bits to it
to carry home.

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