Can't mount cd9660 file system.

[Gary W. Swearingen]

If you have doubts about your CD (but you probably shouldn't),
this should help:

iso_file="backup.iso"

blocksize=2048
    ## *** WARNING *** DVDs might be different *** WARNING ***
    ## Block size of ISO CDs. Nothing else will work (esp,in dd command).
blocks=$(( $(ls -l ${iso_file} | awk '{print $5;}') / ${blocksize} ))
bytes=$(( ${blocks} * ${blocksize} ))
if dd if=/dev/acd0 count=${blocks} bs=${blocksize} | diff - ${iso_file}; then
    echo "NOTICE: Comparison OK.  The CD seems OK."
else
    echo "ERROR: The CD and file differred."
fi