I am about to upgrade Ubuntu 13.04 to Ubuntu 13.10.
Internet speed is slow and so it would take many hours for the same.
So, is there any tool or way to handle or take care of this. Suppose my Internet disconnects while upgrading, how to take care of that? Can it be resumed later at whatever point the Internet disconnects?
If you are using apt-get for upgrading, there is no problem, because it resumes where it left off. The way apt-get operates is that it first decides what packages are necessary, downloads all of these, and then dpkg installs them. The download process is interruptible, like rsync and wget, for example, but apt has its own internal method for dealing with that. It does not call out to external software. The downloaded and partially downloaded files are put in /var/cache/apt.
This is probably true of aptitude as well, and other methods are in most cases probably front-ends to these programs, so I don't see a problem.
I used sudo do-release-upgrade and after the network was interrupted I just had to run:
dpkg --configure -a
apt-get update
apt-get upgrade
reboot
While it does not answer your question directly, my suggestion would be not to upgrade through sudo do-release-upgrade, if that is what You are planning. Something may go wrong and you will have a broken system. It happened to me once. I would suggest backing up your data (/home folder etc) and software and do a clean install of the upgraded OS.
apt-getfor upgrading, there is no problem, because it resumes where it left off. This is probably true of aptitude as well, and other methods is in most cases probably front-ends to these, so I don't see a problem.