1.4. Automount

barebox supports automatically mounting filesystems when a path is first accessed. This is handled with the automount - execute (mount) COMMAND when PATH is first accessed command. With automounting it is possible to separate the configuration of a board from actually using filesystems. The filesystems (and the devices they are on) are only probed when necessary, so barebox does not lose time probing unused devices.

Typical usage is for accessing the TFTP server. To set up an automount for a TFTP server, the following is required:

mkdir -p /mnt/tftp
automount /mnt/tftp 'ifup -a && mount -t tftp $global.net.server /mnt/tftp'

This creates an automountpoint on /mnt/tftp. Whenever this directory is accessed, the command ifup eth0 && mount -t tftp $eth0.serverip /mnt/tftp is executed. It will bring up the network device using ifup - bring a network interface up and mount a TFTP filesystem using mount - mount a filesystem or list mounted filesystems.

Usually the above automount command is executed from an init script in /env/init/automount. With the above, files on the TFTP server can be accessed without configuration:

cp /mnt/tftp/linuximage /image

This automatically detects a USB mass storage device and mounts the first partition to /mnt/fat:

mkdir -p /mnt/fat
automount -d /mnt/fat 'usb && [ -e /dev/disk0.0 ] && mount /dev/disk0.0 /mnt/fat'

To see a list of currently registered automountpoints use automount -l.