[Xastir] Rebuild

[Dexter N Muir]

Hi all
    This is quite likely a 'newbie' question, but with history.
    My system is Kubuntu amd64, originally installed as 14.04 and 
upgraded. I had bypassed the login prompt, being the only 
computer-literate denizen, but have since added eldest grandson to the 
household. Somewhere along the line I lost the ability to re-enable the 
password prompt at login, and having had no response to my queries at 
kubuntuforums.net I gave up and formatted /, reinstalling from the 
ground up.  With this I have lost several 'homebuilt' programs so tried 
rebuilding them. I ran up against a brick wall: any attempt at 
reinstalling build-essential results in an error:

Media change: please insert the disc labeled
  'Kubuntu 16.04 LTS _Xenial Xerus_ - Release amd64 (20160420.1)'
in the drive '/media/cdrom/' and press [Enter]

My reinstall was done from a live USB stick, so I have no CD/DVD disc.

I've long been a user and fan of Lee's cvs script, and the git variant, 
so tried this, hoping it might detect parts of build-essential and just 
go get the other bits, but no: back against the brick wall. Any hints 
here, anybody?
73
Dex, ZL2DEX