Here is an example script that I'm using to read the flash contents to a file once and update it as I flash newer versions of the software:
#!/bin/sh
flashrom="flashrom" programmer="ft2232_spi:type=openmoko,divisor=8"
contents="~/flash-contents.img" image="$1"
if [ -z $image ] then echo "Reading initial flash contents"
timeb=$( date +%s ) $flashrom -p $programmer -r $contents timea=$( date +%s )
echo "Time: "$(( $timea - $timeb ))" seconds" else echo "Writing new flash contents"
timeb=$( date +%s ) $flashrom -p $programmer -w $image -C $contents --noverify timea=$( date +%s )
cp $image $contents
echo "Time: "$(( $timea - $timeb ))" seconds" fi