how I got usb sticks and card reads mounted/unmounted automatically (using udev)

From: H. S. (greatexcalibur_at_yahoo.com)
Date: 11/08/04

  • Next message: H. S.: "Re: USB flash disk" 
    To: debian-user@lists.debian.org
Date: Mon, 08 Nov 2004 00:26:36 -0500

    First of all, here is what I have installed:
    #> dpkg -l gnome-volume-manager gnome-desktop* udev hotplug | grep '^ii'
    ii gnome-volume-m 1.0.2-3 GNOME daemon to auto-mount and manage
    media
    ii gnome-desktop- 2.6.1-2 Common files for GNOME 2 desktop apps
    ii gnome-desktop- 60 The GNOME Desktop Environment
    ii udev 0.040-1 /dev/ management daemon
    ii hotplug 0.0.20040329-1 Linux Hotplug Scripts

    To get icons of devices that you have listed in your /etc/fstab (whether
    they be USB sticks, card readers or anything else) you need
    gnome-volume-manager (KDE has something similar, but I have not
    experimented with that). I have tried the following method successfully
    in Debian Sarge and Sid.

    Now to automatically detect if a device is connected hot (USB stick,
    card reader, etc.) you need udev. Then to make udev make a /dev/<file>
    for the device that you connect, you need to tell udev what to look for.
    This is done in a rules file in /etc/udev/rules.d/. This directory can
    have as many rules as as you need. I have made one single rule file for
    all my gadgets:
    > ls -l /etc/udev/rules.d/
    total 1
    -rw-r--r-- 1 root root 930 2004-10-30 17:22 udev_hs.rules
    lrwxrwxrwx 1 root root 13 2004-10-18 12:10 udev.rules -> ../udev.rules

    Here the udev.rules link is the one that is there by default. The other,
    udev_hs.rules is the rules file that I created (yes, it is just a text
    file).

    Creating the Rules file:
    To create the rules file, you need to know about what information udev
    detects from the device that is connected. This is very nicely explained
    here: http://www.reactivated.net/udevrules.php (a must read).

    Using this information, I made this file:
    #-----------------------------------------------------
    > cat /etc/udev/rules.d/udev_hs.rules
    #Rules created by HS,29Oct,2004
    #In these rules, whatever devices I create, I give them a prefix of
    "hs-" just
    #to keep them separate from system devices. Not sure if this is
    necessary but
    #just in case ...

    #to find out info a USB device, plug it in any USB port of laptop and give
    #the command "udevinfo -a -p /sys/block/sd[ab]" where [ab] means either
    a or b
    # or appropriate character here.

    #the following rule is for the Lexar 256MB jump drive
    BUS="usb", KERNEL="sd*", SYSFS{product}="JUMPDRIVE ELITE",
    NAME="hs-jd-%k", SYMLINK="hs-jd-usb%n"

    #rule for the SanDisk ImageMat 6-in-1 memory cards reader
    # the '1' at the end is because the cards are sda1, sdb1, e.g.
    #The "?" in ID field is becuase kernel give the device ID's in that pattern,
    #this was observed by trying out "udevinfo -a -p /sys/block/sda" command
    with
    #sda, sdb, sdc and sdd.
    BUS="scsi", ID="*:0:0:0", SYSFS{model}="ImageMate 6 in 1",
    NAME="hs-usb-cr-%k"
    #-----------------------------------------------------

    This file essentially is for two devices, the first one is the Lexar
    Jumpdrive and the second one is a SanDisk 6-in-1 card reader.

    The first one was simple, I just plugged in the jump drive and checked
    what "udevinfo -a -p /sys/block/sd[abc..]" said ([abc..] mans try 'a'
    and if that doesn't work then try 'b' if not c and so on.). I picked the
    USB section (that is why there is BUS="usb") of the output. So the first
    rule says (my rough translation):
    a. On the BUS=usb
    b. Look for kernel message of "sd*" where * means anything
    c. If you see SYSFS{product}="JUMPDRIVE ELITE" then make a file in /dev
    with the name of hs-jd-%k, where %k is replaced by sda, sdb, sdc or
    whatever the kernel detected the drive as.
    d. Make a symlink named hs-jd-usb%n which points to the file made in
    step (c) above. (okay, not sure why I put %n there, but I guess I was
    experimenting with multiple paritions in one USB stick and you may not
    realy need that if you have just one partition on your jump drive).

    So, if I now plug in my Lexar Jumpdrive, I get:
    > udevinfo -a -p /sys/block/sda
    <SNIP><SNIP>
       looking at the device chain at
    '/sys/devices/pci0000:00/0000:00:1f.2/usb1/1-1':
         BUS="usb"
         ID="1-1"
         SYSFS{bConfigurationValue}="1"
         SYSFS{bDeviceClass}="00"
         SYSFS{bDeviceProtocol}="00"
         SYSFS{bDeviceSubClass}="00"
         SYSFS{bMaxPower}="100mA"
         SYSFS{bNumConfigurations}="1"
         SYSFS{bNumInterfaces}=" 1"
         SYSFS{bcdDevice}="2000"
         SYSFS{bmAttributes}="80"
         SYSFS{detach_state}="0"
         SYSFS{devnum}="3"
         SYSFS{idProduct}="a400"
         SYSFS{idVendor}="05dc"
         SYSFS{manufacturer}="LEXAR MEDIA"
         SYSFS{maxchild}="0"
         SYSFS{product}="JUMPDRIVE ELITE"
         SYSFS{serial}="0A4EEC11010415071004"
         SYSFS{speed}="12"
         SYSFS{version}=" 2.00"
    <SNIP><SNIP>

    And I get these files created in /dev:
    > ls -1 /dev/*hs*
    /dev/hs-jd-sda
    /dev/hs-jd-usb

    Why do I need the symlink? Because depending on other USB devices
    connected to my computer, the drive could have been detected as sdb,
    sdc. etc. No matter what it is detected as, as long as it is "sd*" it
    will have a symlink hs-jd-usb pointing to it. This symlink will be used
    in /etc/fstab to make a mount point for the USB stick.

    Making a Mount Point in /etc/fstab
    Now I have this line in /etc/fstab to tell gnome-volume-manager about
    the usb stick mount point:
    #the following it to mound USB Jump drive from udev created symlinks
    /dev/hs-jd-usb /media/usbstick auto rw,user,noauto 0 0

    Of course, I also have the /media/usbstick directory. And lo and behold,
    gnome-volume-manager mounts the USB stick and shows an icon on the
    desktop (the icons is named as "usbstick", same as the mount point). If
    you pluck out the USB stick, it is unmounted and the icon dissappears
    from the desktop. Pretty neat, eh.

    Now, the second rule I have in my rules files is for the 6-in-1 SanDisk
    card reader. It has 4 slots in all and each one seems to be seen as a
    different parition at least. BUS="usb" didn't give me enough
    information(or maybe I didn't look hard enough). I did notice that in
    BUS="scsi" I was getting a unique ID="*:0:0:0" for each slot and also a
    SYSFS{model}="ImageMate 6 in 1". Armed with this information I made the
    rule in rules file (see above) and I made these lines in /etc/fstab:
    /dev/hs-usb-cr-sda1 /media/card-cf auto
    noauto,user,rw,sync,noatime,umask=0077 0 0
    #/dev/hs-usb-cr-sdb1 /media/card-sm auto
    noauto,user,rw,sync,noatime,umask=0077 0 0
    #/dev/hs-usb-cr-sdc1 /media/card-sd auto
    noauto,user,rw,sync,noatime,umask=0077 0 0
    /dev/hs-usb-cr-sdd1 /media/card-ms auto
    noauto,user,rw,sync,noatime,umask=0077 0 0

    along with the corresponding mount point directories in /media.

    Here I have only used sda1 and sdd1 until now so the other two are
    commented out (I don't have other kind of memory cards). If I plug in
    the card reader and put in a CF card, I get an icon on my desktop. Pluck
    out the card and the icon dissappears.

    However, with udev, you can get some rare quirks. For example, in my
    case, ppp_generic has to be mentioned in /etc/modules (I am using 2.6.7
    kernel, remember?) otherwise ppp0 connection fails to get fired up at
    boot time and has to be done using pppoeconf.

    If you have questions, feel free to ask.
    GL,
    ->HS 

    -- 
To UNSUBSCRIBE, email to debian-user-REQUEST@lists.debian.org 
with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org
  • Next message: H. S.: "Re: USB flash disk"