Comodo manual updater (Incomplete)

cav-updater.sh

#!/usr/bin/sh

echo "[+] Checking for updates..."

path_bases_cav="/c/Program Files/COMODO/COMODO Internet Security/scanners/bases.cav"
update_url="http://cdn.download.comodo.com/av/updates58/sigs/bases/bases.cav"

hash_check () {
	# Download first 256 bytes (after header) of remote stream
	tmp_first_256_remote=`mktemp`
	start=16
	stop=802400
	curl --silent -r $start-$stop -o $tmp_first_256_remote $update_url
	md5_first_256_remote=$(md5sum $tmp_first_256_remote | \
							cut -d " " -f 1)
	
	md5_first_256_system=$(dd if="$path_bases_cav" skip=$start bs=1 count=$((stop-start+1)) 2>/dev/null | \
								md5sum | \
								cut -d " " -f 1)
	echo $md5_first_256_remote
	
	echo $md5_first_256_system
	
}

system_cav_size=$(du -b "$path_bases_cav" | \
				cut -d $'\t' -f 1)
				
remote_cav_size=$(curl --silent --head $update_url | \
			grep "Content-Length:" | \
			cut -d " " -f 2)				
				
printf "[+] System bases.cav filesize = %d bytes\n" $system_cav_size
printf "[+] Remote bases.cav filesize = %d bytes\n" $remote_cav_size

if [ $remote_cav_size -gt $system_cav_size ]
then
	echo "[+] Updates detected"
	hash_check
else
	echo "[+] No updates found"
fi