Generating locales (this might take a while)...
Generation complete.
pwconv: failed to change the mode of /etc/passwd- to 0600
Using CD-ROM mount point /cdrom/
Identifying... [10a477711460d272936f36f0f9a11a8f-2]
Scanning disc for index files...
Found 4 package indexes, 0 source indexes, 0 translation indexes and 2 signatures
Found label 'Ubuntu 16.04.4 LTS _Xenial Xerus_ - Release amd64 (20180228)'
This disc is called: 
'Ubuntu 16.04.4 LTS _Xenial Xerus_ - Release amd64 (20180228)'
Copying package lists...gpgv: Signature made Wed Jul 25 03:21:41 2018 UTC using RSA key ID EFE21092
gpgv: Good signature from "Ubuntu CD Image Automatic Signing Key (2012) <cdimage@ubuntu.com>"
gpgv: Signature made Wed Feb 28 19:14:57 2018 UTC using RSA key ID EFE21092
gpgv: Good signature from "Ubuntu CD Image Automatic Signing Key (2012) <cdimage@ubuntu.com>"

Reading Package Indexes... 0%

Reading Package Indexes... Done
Writing new source list
Source list entries for this disc are:
deb cdrom:[Ubuntu 16.04.4 LTS _Xenial Xerus_ - Release amd64 (20180228)]/ bionic main restricted
deb cdrom:[Ubuntu 16.04.4 LTS _Xenial Xerus_ - Release amd64 (20180228)]/ xenial main restricted
Repeat this process for the rest of the CDs in your set.