There used to be this great resource called Linux Documentation Project. It's not as active as it used to be but it produced some really book-quality documents,

There used to be this great resource called Linux Documentation Project. It's not as active as it used to be but it produced some really book-quality documents, including the Advanced Bash Scripting Guide at https://www.tldp.org/LDP/abs/html/ https://www.tldp.org/LDP/abs/html/ . Read it! It's great. But know that a lot of bash scripting isn't really in bash, it's really required to be proficient with grep, sed, cut, dc and a few other text processing utilities. Learn those! Then are are a few other tricks to be mindful of: be mindful of spaces (wrap your variable substitution in double quotes, mostly), be mindful of sub-shells (piping to something that sets variables can be problematic), and a few other things that can really only be learned by reading good code. But it's also good to know when you shouldn't venture further. My rule of thumb is when I'm using arrays or hash maps, then it's a good idea to move to another language. That's probably Python nowaways. A lot of people use tons of awk or perl snippets inside their bash scripts, that can also be a sign that it's time to move the whole script over.