Question

I am using set -e to stop execution of a script on first error.

The problem is that this does not tell me what went wrong.

How can update a bash script so it will display me the last command that failed?

Answer 1

Instead of set -e, use an ERR trap; you can pass $BASH_LINENO in to get the specific line number on which the error occurred. I provide a script taking advantage of this in my answer at https://stackoverflow.com/a/185900/14122

To summarize:

error() {
   local sourcefile=$1
   local lineno=$2
   # ...logic for reporting an error at line $lineno
   #    of file $sourcefile goes here...
}
trap 'error "${BASH_SOURCE}" "${LINENO}"' ERR