There are libraries for unit testing shell scripts.

And also,

From https://news.ycombinator.com/item?id=26906351 :

> From "Bash Error Handling" https://news.ycombinator.com/item?id=24745833 : you can display the line number in `set -x` output by setting $PS4:

  export PS4='+(${BASH_SOURCE}:${LINENO}) '
  set -x

And

    trap '(read -p "[$BASH_SOURCE:$LINENO] $BASH_COMMAND?")' DEBUG