Customizing your login on Purdue CS computers (WIP)
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---
date: "2014-04-21"
---

> This article is currently a Work-In-Progress, but it may be enough
> to get someone started, so I'm publishing it as is.

Most CS students at Purdue spend a lot of time on the lab boxes, but
don't know a lot about them.  This document tries to fix that.

The lab boxes all run Gentoo.

## About GDM

They run `gdm` (Gnome Display Manager) 2.20.11 for the login screen.
This is an old version, and has a couple behaviors that are slightly
different than new versions, but here are the important bits:

System configuration:

 - `/usr/share/gdm/defaults.conf` (lower precidence)
 - `/etc/X11/gdm/custom.conf` (higher precidence)

User configuration:

 - `~/.dmrc` (more recent versions use `~/.desktop`, but Purdue boxes
   aren't running more recent versions)

## Purdue's GDM

Now, `custom.conf` sets

    BaseXsession=/usr/local/share/xsessions/Xsession
    SessionDesktopDir=/usr/local/share/xsessions/

This is important, because there are *multiple* locations that look
like these files; I take it that they were used at sometime in the
past.  Don't get tricked into thinking that it looks at
`/etc/X11/gdm/Xsession` (which exists, and is where it would look by
default).

Values for `~/.dmrc:Session`:

 - `custom`: Executes `~/.xsession`
 - `default`: Executes ~/.Xrc.cs
 - `fvwm2`: ???
 - `gnome`: ...
 - `kde`: Displays a message saing KDE is no longer available
 - `failsafe`: Runs a single xterm window (NOPE)