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... [286dc9d27fa71957dbdba26de5c7ba3d-2]
Scanning disc for index files...
Found 2 package indexes, 0 source indexes, 0 translation indexes and 1 signatures
Found label 'Ubuntu 16.04.1 LTS _Xenial Xerus_ - Beta amd64 (20170208)'
This disc is called: 
'Ubuntu 16.04.1 LTS _Xenial Xerus_ - Beta amd64 (20170208)'
Copying package lists...gpgv: Signature made Wed Feb  8 07:25:49 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 16.04.1 LTS _Xenial Xerus_ - Beta amd64 (20170208)]/ xenial main restricted
Repeat this process for the rest of the CDs in your set.