When running prepare_grub_to_access_device inside of the here document a file
descriptor to a temporary file is leaked. When prepare_grub_to_access_device
calls various lvm related commands these will complain about this.
Minimum example:
<< EOF
"$(lvs)"
EOF
Avoid this by calling prepare_grub_to_access_device before assembling the
output.
echo "Found Grml ISO image: $grmliso" >&2
title="Grml Rescue System ($grml)"
+ grub_prep=$(prepare_grub_to_access_device "$device" | sed -e "s/^/ /")
cat << EOF
menuentry "${title}" {
-$(prepare_grub_to_access_device "$device" | sed -e "s/^/ /")
+${grub_prep}
iso_path="${rel_dirname}/${grml}"
export iso_path
kernelopts=" $CUSTOM_BOOTOPTIONS $additional_param "