How to determine if disk is compact flash or standard hard drive

Question

I need to determine in a shell script if a given block device (e.g. /dev/sda) is a compact flash disk or a regular hard drive. Google did not help me out for once, and while udevadm info --query=all --name=sda gives me lots of information, theres nothing I recognize to mean "I'm definately (not) a flash drive" or "I'm definately (not) a hard drive".

Is it possible to distinguish these two types of storage devices?

I use Ubuntu 10.10.

Answer 1

It seems likely (though there may be caveats) that this will distiguish between flash-based storage devices and traditional hard disks:

is_compact_flash ()
{
    hdparm -I $1 | sed -n '\_Commands/features:_,\_Security:_p' | \
        grep -q CFA && return 0 || return 1
}

disk=/dev/sda
if is_compact_flash $disk; then
    echo "$disk is a compact flash disk"
else
    echo "$disk is not a compact flash disk"
fi

EDIT: Added sed command to guard against model or serial containing CFA.