I think this is the right answer, assuming OP actually wants to get better at bash and not route around his original question by learning stuff that isn't bash.

I think this is the right answer, assuming OP actually wants to get better at bash and not route around his original question by learning stuff that isn't bash. I use bash/shell scripts frequently and have many running 'in production' as cron jobs th at run various jobs or manipulate data for other jobs to run on. One thing I really like about pure shell is that it's extremely portable and transparent about what it's doing. I still have to re-learn control structures almost everytime I write a new script, I don't try and memorize [[]] vs [] and all the weird ways equality can work, I just google each time and answers are always on top (once you know what you're looking for).