[periegetes]

Bash as a scripting language is actually pretty amazing. It gives you everything you need to perform some quick-and-dirty tasks with minimal overhead. If you need only work on sequential data, files and processes, it's a perfect match.

It's not a full-fledged programming language by any stretch of the imagination (lacking structures more complex than associative arrays), but it's damn good for scripts of all sorts.

As an example, I've reimplemented a subset of Ansible (a command able to send "modules" on multiple machines via SSH and capturing+caching their output for subsequent queries) in ~150 lines of Bash. Considering that the size of Ansible, written in the more proper Python, is ~15000 LOC, I'd say Python is the much lesser scripting language.

Edit: to answer the OP's question, the documentation I've found most helpful to learn Bash is the one present on the Linux Documentation Project, with the page for arrays deserving special mention : http://tldp.org/LDP/abs/html/arrays.html. I spent a lot of time reading the manual before stumbling upon that documentation, and none of it really clicked until I had a few examples before my eyes.

[ribs]

Typically a program like Ansible will have the majority of its use cases implemented in a minority of its code, while the rest of the code will be there to support special cases, edge cases, rare use cases, etc. So that contributes to the disparity in size.

[dkns]

Ansible has to take into account numerous edge cases, operating systems, backwards compatibility, etc. etc. Of course it's much, much bigger than your 150 lines bash script.