To be honest, I haven't encountered any poorly written shell code in my career, only good one. The worst stuff I've seen till now was written in PHP and VBScript.

I agree with the slides, one should not do complex stuff with shell scripts. However there is one further good reason to do some things in shell script: Every *nix sysadmin that is worth his/her salary MUST be able to read and maintain shell scripts. So shell is the lowest common denominator among system people.

On the other hand the poor Windows sysadmins are nowadays supposed to learn PowerShell. While it's much more powerful than CMD and WSH, the syntax is a mess.

Your article does a good job in explaining some issues with agile.I think the strength of agile is to quickly produce some application level software that works OK-ish with a mixed bunch of developers. Some online shop software written in J2EE would be a good example for this. IMO if you are an extraordinary developer producing cleaner and more efficient code than the people around you, working in a religiously agile project will kill your passion before the first seven Scrum sprints have finished because you're confrontend with shitty code and short sighted architecture all the time.

A good example of how a non-agile project succeeds is the Linux kernel. Linus Torvalds and his mates do a fantastic job driving this software.