The xinit program is used to start the X Window System server. The first client program listed will be launched. This is launched from /etc/init. In cases in which a program is not listed, xinit will look for a file in the user's home directory. This file (shell script) is called .xinitrc. If this shell script does not exist, you can create one in your home directory that can be used.
Let's look at this file again:
#!/bin/sh xrdb -load $HOME/.X11defaults xscreensaver -timeout 10 & xterm -geometry 80x30+10+10 &
The first line in the .xinitrc file is used to declare the shell in which the script is written. Whatever shell you ultimately decide to use will dictate the commands you use within it. What this means is that if ...