Generating locales...
  en_US.UTF-8... done
Generation complete.
pwconv: failed to change the mode of /etc/passwd- to 0600
Using CD-ROM mount point /cdrom/
Identifying... [a76b4dffbea885a0c4926e3de978e894-2]
Scanning disc for index files...
Found 4 package indexes, 0 source indexes, 0 translation indexes and 1 signatures
Found label 'Ubuntu-GNOME 16.04 LTS _Xenial Xerus_ - Alpha amd64 (20151211)'
This disc is called: 
'Ubuntu-GNOME 16.04 LTS _Xenial Xerus_ - Alpha amd64 (20151211)'
Copying package lists...gpgv: Signature made Fri Dec 11 16:08:39 2015 UTC using DSA key ID FBB75451
gpgv: Good signature from "Ubuntu CD Image Automatic Signing Key <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-GNOME 16.04 LTS _Xenial Xerus_ - Alpha amd64 (20151211)]/ xenial main multiverse restricted universe
Repeat this process for the rest of the CDs in your set.