shellscript conditional to check for external disk

[Roland Smith]

On Sat, Jun 21, 2008 at 09:44:09PM +0000, Helge Rohde wrote:
> Hello List,
> 
> I need to write a backup script, and one of the required actions would be a 
> copy of the backup to an external firewire drive. I would like to make this 
> as easy as possible for the local staff, so i'd like to check whether the 
> drive is attached, if necessary mount it, copy over the backup  and unmount 
> it again, so that the local staff can swap the external disks when they're 
> not used.
>  
> Is there a canonical way to achieve what i want? I played with the idea of 
> simply checking for /dev/da0s1d's existance, but that won't disappear on 
> disconnect, so that would leave the  is a possibility that although da0 is 
> in /dev, it might not be connected.

Use glabel(8) to give the device an unique label. There is no telling
which device /dev/da0s1d is pointing to! After labeling you can check
for /dev/<fstype>/<yourlabel>, which should be unique.

Make sure to unmount the drive at the end of the backup script, or
you'll get a kernel panic when staff pulls the plug on a mounted device.

Roland
-- 
R.F.Smith                                   http://www.xs4all.nl/~rsmith/
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