Sorry, when you said you had a 1.5GB file, I assumed you meant a large movie or something that needed splitting for archive onto CD. I assume now you meant the tar file is 1.5GB, not the contents?
One way I've found that works is to create a file beforehand (you could generate this file within a script fairly easily) that contains lines like this
Code:
n archive02.tar
y
n archive03.tar
y
Then you run a command like this:
tar cf archive01.tar -M -L 665600 < names.list
the contents of names.list replace the text you would need to type manually to continue the archive.
These tar files are partially extractable. As long as a file is fully contained within the piece you are working with, it should extract fine. If you want to restrict files so they cannot create archive boundaries, that will be more complicated.