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idea: usb disk becomes available, do something

So I've been using this method to backup for some time: USB connection to an external SATA docking station, 1TB disk goes there. I then get on my system run dmesg, confirm the output below, mount /dev/sdd1 /opt.bk, then run a script I have that does all the backup magic.

I'd like to extend/improve this scheme by automating most, or possibly all of it. I'm wondering if anyone can tell me 1) is there a file in /proc that will tell me if this disk is available or not (I've looked and I'm not finding it) 2) does anyone have an example of a daemon or cron run job that watches for something in proc then acts on it?

Code:

usb 1-1.4: new high speed USB device using ehci_hcd and address 3

usb 1-1.4: configuration #1 chosen from 1 choice

Initializing USB Mass Storage driver...

scsi6 : SCSI emulation for USB Mass Storage devices

usb-storage: device found at 3

usbcore: registered new driver usb-storage

usb-storage: waiting for device to settle before scanning

USB Mass Storage support registered.

  Vendor: ST        Model: ST1000DM003-9YN1  Rev: 2.02

  Type:  Direct-Access                      ANSI SCSI revision: 04

SCSI device sdd: 1953525168 512-byte hdwr sectors (1000205 MB)

sdd: Write Protect is off

sdd: Mode Sense: 23 00 00 00

sdd: assuming drive cache: write through

SCSI device sdd: 1953525168 512-byte hdwr sectors (1000205 MB)

sdd: Write Protect is off

sdd: Mode Sense: 23 00 00 00

sdd: assuming drive cache: write through

 sdd: sdd1

sd 6:0:0:0: Attached scsi disk sdd

sd 6:0:0:0: Attached scsi generic sg4 type 0

usb-storage: device scan complete

What I have in my backup script is to mount my USB drive, test if the backup directory now exists, run the backup, then umount.
The backup script runs from a cron job and adds start and end times to a log file in my home directory so I know how long its taking and whether it completed.

If you want to start a your backup script once your disk becomes available have a look at udev scripts: http://reactivated.net/writing_udev_rules.html

and if you use udev, you can tie the rule to a specific volumn name so that it backs up only when you plug in a device labeled for backup...

I used this. It's a bit sloppy but seems to work fine.

Code:



cat /proc/bus/usb/devices  | grep "Driver=usb-storage" >/dev/null

if [ "$?" -ne "0" ]; then

  exit 1

fi



dmesg | tail -n 10  | grep sdd1 > /dev/null

if [ "$?" -ne "0" ]; then

  exit 1

fi