What software does the Ubuntu installer run on?

Sorry if somebody has already asked this question, I haven't found anything else.

When you install Ubuntu, some sort of program is run, like where you set different options for your OS installation. Does anyone know what the software is being run?

Thanks.

Solution 1:

As Pilot6 says, when you install Ubuntu using the graphical installer in a live environment, the installer you are using is Ubiquity. The desktop ISO images, which are the most popular way to install Ubuntu, use Ubiquity. (See also, What is ubiquity?.)

In contrast, when you install Ubuntu using the text-based server, minimal, or -- for older releases that had them -- the alternate ISO image, that uses the Debian installer. More precisely, it is "d-i," which is the Debian installer with the necessary changes for Ubuntu.

As the Installer/Development page on the Ubuntu wiki (by "Contributors to the Ubuntu documentation wiki") says:

Ubuntu and its various flavours (Kubuntu, Edubuntu, Xubuntu) have two installers. One is a modified version of the Debian installer, known as "d-i", and is written in POSIX shell script and C. The other, Ubiquity, is used on our live CD (or "desktop CD"), features a from-scratch user interface design, and has a good deal of front-end code written in Python, but behind the scenes still uses d-i code for many back-end tasks where it's important that we don't end up maintaining two implementations.

Solution 2:

This is ubiquity.

Ubiquity is a simple graphical live CD installer designed to integrate well with Debian- and Ubuntu-based systems, written largely in Python, using d-i as a backend for many of its functions for ease of maintenance.

^{— Ubiquity, in the Ubuntu wiki, by "Contributors to the Ubuntu documentation wiki"}