Is it safe to manually perform 'apt-get update' 's operation?

I am trying to **keep one my Ubuntu systems up-to-date**. The intended target is **Not Connected to the internet**. Am trying to get all the needed info from another machine with internet access. After a bit of study, I found a way to achieve this. Can you please tell me if this is correct & safe? > Here is my understanding of the apt-get process.. > > 1. First, we run the command ***'apt-get update'*** : This connects to all the repositories mentioned in the *'/etc/apt/sources.list'*.. And, > **downloads all the Packages.gz** files like > (**in.archive.ubuntu.com/ubuntu/dists/trusty/main/binary-amd64/Packages.gz**) > & **saves them in a similar name** under *'/var/lib/apt/lists'* (for the > above mentioned url the corresponding file is > **in.archive.ubuntu.com_ubuntu_dists_trusty_main_binary-amd64_Packages**) > 2. Then, when we run ***'apt-get upgrade'*** (or) ***'apt-get install pkg_name'***, this **checks the locally installed package list with the local meta-data** > downloaded & stored at *'/var/lib/apt/lists'*. And, then gets the > download url from that & asks for user confirmation **before downloading > & installing the required packages**. This is my plan to keep the isolated machine up-to-date.. 1. **Get the list of packages to download** from the *'/etc/apt/sources.list'* conf file at the target machine.. 2. **Download the meta-data** files Packages.gz **at another machine**.. 3. **Copy** these files **to target machine's *'/var/lib/apt/lists'*** under appropriate filename. 4. **Run** the ***'apt-get --print-uris upgrade'*** (or) *'apt-get --print-uris --yes install pkg_name'* to get the list of all the packages needed for that machine. 5. **Download these packages** again **at the second machine**. 6. **Copy them to the target machine**. 7. **Run the *'dpkg -i pkg_list'*** to install all the missing packages. I am able to achieve my goal using this process. My question is : **Is this correct & reliable? Or is there an easier way to achieve this?** Rangaraj