Torkel,
The safest way to make a copy of the current card (but perhaps not the easiest) would require that you shutdown the Beaglebone and insert the microSD card in another PC.
On Windows, you can copy it to an .img file using Win32DiskImager. You could then use Win32DiskImager to copy the .img file onto other microSD cards.
On Linux, you would use the dd command. There are various options that affect the speed of the dd command, but the following will work (run as root):
To backup:
dd if=/dev/sde of=sdbackup.img
To restore onto a microSD card:
dd if=sdbackup.img of=/dev/sde
Of course, the “/dev/sde” part will vary depending on your configuration: it might be /dev/sdc or /dev/sdd or whatever. Check the output of dmesg after inserting the microSD card to see what device letter is assigned to it.
Having said all that, it is possible to make a “hot” copy of the microSD card while it is running the Beaglebone. That’s actually what I do, and so far I’ve been able to restore those copies onto other microSD cards and use them in Beaglebones without problems.
So, to make a hot copy onto a USB drive (you probably want to compress it):
dd if=/dev/mmcblk0 | gzip -1 > media/sda1/sdbackup.img.gz
To make a hot copy over SSH from a Linux PC, enter the following command on the Linux PC:
ssh root@192.168.1.100 dd if=/dev/mmcblk0 | gzip -1 - | dd of=sdbackup.img.gz
The IP address will, of course, need to be changed to your Beaglebone’s address, and SSH will prompt for the root password.
Dan.