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... [5b41d7e825d5d78bbdc5a2da9c965622-2]
Scanning disc for index files...
Found 4 package indexes, 0 source indexes, 0 translation indexes and 1 signatures
Found label 'Ubuntu-MATE 16.04.2 LTS _Xenial Xerus_ - Release amd64 (20170215)'
This disc is called: 
'Ubuntu-MATE 16.04.2 LTS _Xenial Xerus_ - Release amd64 (20170215)'
Copying package lists...gpgv: Signature made Wed Feb 15 21:16:55 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-MATE 16.04.2 LTS _Xenial Xerus_ - Release amd64 (20170215)]/ xenial main multiverse restricted universe
Repeat this process for the rest of the CDs in your set.