Your script contains errors as well, for example if you have dos2unix installed your install works but if you don't like I did then it will fail with dependency issues.
I found this by accident as I was making a script file of this to give to my friend who is new to Linux and because I made the scripts on windows I directed him to install it, at the time I did not have dos2unix installed thus I got errors.
here is a copy of the script I made for your solution but have dos2unix installed.
#!/bin/sh
echo "deb http://ftp.debian.org/debian sid main" >> /etc/apt/sources.list
apt-get update
apt-get -t sid install libc6 libc6-dev libc6-dbg
echo "Please remember to hash out sid main from your sources list. /etc/apt/sources.list"
this script has been tested on 3 machines with no errors.