adding source URI for emacs install

Question

I'm attempting to install emacs 25.1 on my ubuntu 16.04 system from the following PPA:

https://launchpad.net/~ubuntu-elisp/+archive/ubuntu/ppa

I've added the Ubuntu Emacs Daily Snapshot PPA to my system, and attempted to install the build dependencies.

I ran:

>sudo apt install build-essential checkinstall

and then:

>sudo apt-get build-dep emacs24

But I get the following output:

Reading package lists... Done
E: You must put some 'source' URIs in your sources.list

I take this to mean apt-get can't find the build dependencies, isn't this what adding the PPA to my system with

>sudo add-apt-repository ppa:ubuntu-elisp/ppa
>sudo apt-get update

should have corrected? I've edited the sources.list file in /etc/apt by individually uncommenting all the pairs of deb and deb-src lines, but that didn't solve the problem.

Answer 1

You don't need build-dep to install emacs snapshot. Just make sure you run

sudo add-apt-repository ppa:ubuntu-elisp/ppa
sudo apt-get update

as you mentioned, and then

sudo apt-get install emacs-snapshot
sudo update-alternatives --config emacs

and select emacs-snapshot.

(I gather the source URI build-dep is complaining about are in /etc/apt/sources.list.d/ubuntu-elisp-ppa-xenial.list, but as I said you don't need it unless you are going to compile emacs.)

Answer 2

This issue can be solved by the following steps:

1. open 'Softwares & Updates' from `System Settings.
2. In 'Ubuntu Softwares', check the source code in 'Downloadable from the Internet' section. Then the system will do apt-get update automatically and download the source code.
3. Then you can install the dependencies of emacs.