How to generate partial checksum of a file

Suppose a more complicated case: You need to get your 2nd 1GB part of your first partition. use dd command:

dd bs=1M skip=1024 count=1024 if=/dev/sda1 | md5sum

Note that we haven't used of= part of dd command. So its output will be redirected to standard output, that we piped to the next command.

head -c 1024 | md5sum

should work.

Full example, as requested in comments:

head -c 1024 your_file | md5sum