Start learning another programming language. Maybe two or three. They aren't like spoken languages: there are only a few words, and syntax is explicit.
Programming languages will feel a bit foreign since there are different paradigms involved, but you have a solid perspective to start with.
Since you know bash, you know the environment your programs will run in. Start by learning simple IO with stdin, stdout, and stderr. The rest is basically just different methods to organize your code.
Try a dynamically typed language like Ruby, Python or Lua. It's closest to Bash, but different enough to let you learn the power of a true programming language.
Then try a statically compiled language like F#, C#, OCaml, or Kotlin, depending on what kind of platform you like.
Then try a lower level language like C, Ada or Rust.
There are of course completely different paths you could also take, like tossing Prolog or Haskell in there somewhere, but the above path will cover the basics of what's most widely used in industry, ie. functional, imperative and OO paradigms, curly brace syntax vs indentation based syntax, the common control flow abstractions, statement oriented vs expression oriented languages, and statically and dynamically typed languages.
Hmm might be good to think about this as what career path you'd like. If you're IT for example and want to move into ops or something, maybe you can start looking into writing things for chef or puppet.
You don't really "get told" you're an expert at something-- if you're waiting for someone's certification that you're an expert, then you're probably not an expert.
I don't mean to diminish what I'm sure is your extremely proficient grasp of bash; rather I mean to diminish the way you presented it. If you're an expert, you know it without being told.
I think he's just being modest and not claiming that he's expert, just that he's considered to be one. You're reading way too much into that single sentence.
On the contrary; I've been told I'm expert level at things I don't consider myself an expert in. I always chalked it up to the fact that "the more you know, the more you realise you don't know"
Programming languages will feel a bit foreign since there are different paradigms involved, but you have a solid perspective to start with.
Since you know bash, you know the environment your programs will run in. Start by learning simple IO with stdin, stdout, and stderr. The rest is basically just different methods to organize your code.