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... [8c5892be87f78ac0a8355ea2099c4e0a-2]
Scanning disc for index files...
Found 4 package indexes, 0 source indexes, 0 translation indexes and 2 signatures
Found label 'Ubuntu 16.04.3 LTS _Xenial Xerus_ - Release amd64 (20170801)'
This disc is called: 
'Ubuntu 16.04.3 LTS _Xenial Xerus_ - Release amd64 (20170801)'
Copying package lists...gpgv: Signature made Wed Aug  3 17:49:26 2016 UTC using DSA key ID FBB75451
gpgv: Good signature from "Ubuntu CD Image Automatic Signing Key <cdimage@ubuntu.com>"
gpgv: Signature made Tue Aug  1 11:51:24 2017 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 16.04.3 LTS _Xenial Xerus_ - Release amd64 (20170801)]/ trusty main restricted
deb cdrom:[Ubuntu 16.04.3 LTS _Xenial Xerus_ - Release amd64 (20170801)]/ xenial main restricted
Repeat this process for the rest of the CDs in your set.