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SD card autocopy

Copying photos from the SD card of my camera is a very common task. And always the same pattern. Take the card out of the camera, put it into the sd card reader, wait for the automount popup, browse to the picture directory, select all images, cut all images, browse to my photo directory, create a new folder, name the folder, move to the folder, paste the pictures into it, wait for the finished job.

Sound boring? Sure, it is!

Now, how to make this one a little smarter? Maybe scripting some of those steps is a cool idea. So how would this work in a perfect world?

The idea

Taking the SD card out of the camera and putting it into the SD card reader does not seem to be easily scripted, that's why I focused on the other steps ;-). Okay, I'd like to put the card into the reader, just wait for all the images to be moved and then put the card back into the camera.

But how to reach this goal? Maybe you're interested in my solution...

One thing we need to know: When hotplugging devices to my Ubuntu system the kernel tells the udev daemon about that new device. The kernel informs the udev daemon about a lot of different events, like adding and removing hardware, volumes and so on. But how to get closer to these events?

Digging into udev events

There is an interesting tool named udevadm which can be used to monitor the incoming events. Let's see which events are fired when I put the SD card into the card reader:

> udevadm monitor
monitor will print the received events for:
UDEV - the event which udev sends out after rule processing
KERNEL - the kernel uevent

KERNEL[1316365297.577602] add /devices/pci0000:00/0000:00:1e.0/0000:15:00.2/mmc_host/mmc0/mmc0:b368 (mmc)
KERNEL[1316365297.578091] add /devices/virtual/bdi/179:0 (bdi)
UDEV [1316365297.579008] add /devices/virtual/bdi/179:0 (bdi)
UDEV [1316365297.579058] add /devices/pci0000:00/0000:00:1e.0/0000:15:00.2/mmc_host/mmc0/mmc0:b368 (mmc)
KERNEL[1316365297.580552] add /devices/pci0000:00/0000:00:1e.0/0000:15:00.2/mmc_host/mmc0/mmc0:b368/block/mmcblk0 (block)
KERNEL[1316365297.580644] add /devices/pci0000:00/0000:00:1e.0/0000:15:00.2/mmc_host/mmc0/mmc0:b368/block/mmcblk0/mmcblk0p1 (block)
UDEV [1316365297.617556] add /devices/pci0000:00/0000:00:1e.0/0000:15:00.2/mmc_host/mmc0/mmc0:b368/block/mmcblk0 (block)
UDEV [1316365298.314850] add /devices/pci0000:00/0000:00:1e.0/0000:15:00.2/mmc_host/mmc0/mmc0:b368/block/mmcblk0/mmcblk0p1 (block)

These are a lot of of events, but there is only one needed, so it is needed to choose the correct one. One way would be to try one event after each other, but there is a better way: Now one need to know that it is possible to react on specific events and run some script every time such an event is received. The script is executed and has access to the whole environment which is populated with some useful information.

To get a little more information create a matching udev rule and a small script which appends the whole environment to a temporary dump file:

Store the udev rule in the rules directory /etc/udev/rules.d/99-sd-autocopy.rules:

SUBSYSTEM=="block", ACTION=="add", RUN="/usr/local/bin/sd-autocopy"

The udev daemon should recognize that rule immediately. If a restart of the udev daemon might help.

Now create the script to dump the environment at the path specified in the udev rule /usr/local/bin/sd-autocopy:

echo ======================== >> /tmp/test
env >> /tmp/test

Then make the script executable:

chmod +x /usr/local/bin/sd-autocopy

Now simply plug the SD card of your choice into your SD card reader and have a look at the contents of /tmp/test afterwards. The file should contain information of several events where the single events are separated by the lines of equal sings.

Having these events recorded it is now possible to grab the important information for the script. When looking at the single events we see that there is one ADD event for the added disk and one ADD event for each partition. We are only interested in the partition events and need the first partition of the device, so add the following conditions to the udev rule:


which should result in this rule:

SUBSYSTEM=="block", ACTION=="add", ENV{DEVTYPE}=="partition", ENV{UDISKS_PARTITION_NUMBER}=="1", RUN="/usr/local/bin/sd-autocopy"

After changing the rule, deleting the /tmp/test file and an additional test we can see that the test sd-autocopy script gets only called with the correct event. This event comes with the following environment variables:

DEVLINKS=/dev/disk/by-id/mmc-SDC_0x000006d4-part1 /dev/disk/by-path/pci-0000:15:00.2-part1 /dev/disk/by-uuid/F84E-1690

The sd-autocopy script

With these information the SD card can be identified. It will use the ID_SERIAL and DEVNAME environment variables in the script. Now I identified the tasks which need to be performed by the sd-autocopy script:

  1. Verify the sd card to be a handled one
  2. Mount the partition
  3. Find all images on the partition
  4. Create a folder for each date in a target base path
  5. Move the files to the date specific folder
  6. Unmount the partition

The script is placed in /usr/local/bin/sd-autocopy (just remove the testing code from that file). The finished script can be found in the git next to this README file.

The script can easily be extended by modifying the first few lines:

# Move or copy - or something different
  • USER is needed a) for gathering the target directory and b) for owning the copied files.
  • TARGET holds the path to the target base directory.
  • HANDLED_SERIALS holds a list of space separated serial numbers of the SD cards to use the script for.
  • MOUNT contains the mountpoint for the first partition on the SD card.
  • FILE_MATCH is the matching regex for the files to be copied. It applies to the whole path of the files.
  • TRANSFER defines the transfer mode. For example "mv" to move the files or "cp" to copy them.

The script sends it's log entries to syslog, so you might want to have a look at the syslog files for debugging.

Btw. the script is not limited to handling images. By just modifying the FILE_MATCH pattern it is possible to copy other filetypes.


SD card autocopy (Linux)



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