Get stack trace in Bash shell script/program.

stack_trace.sh

# LICENSE: MIT, wtfpl or whatever OSS license you like
function get_stack () {
   STACK=""
   local i message="${1:-""}"
   local stack_size=${#FUNCNAME[@]}
   # to avoid noise we start with 1 to skip the get_stack function
   for (( i=1; i<$stack_size; i++ )); do
      local func="${FUNCNAME[$i]}"
      [ x$func = x ] && func=MAIN
      local linen="${BASH_LINENO[$(( i - 1 ))]}"
      local src="${BASH_SOURCE[$i]}"
      [ x"$src" = x ] && src=non_file_source

      STACK+=$'\n'"   at: "$func" "$src" "$linen
   done
   STACK="${message}${STACK}"
}

I'm impressed with all improvements I see here. Perhaps somebody would submit their version as an improvement to https://github.com/olivergondza/bash-strict-mode/

P.S. when printing stack traces, it's better to use STDERR

I did it that way so that higher level code can more conveniently capture the output; it can also redirect it to stderr. Either way works, certainly.

I find the arguments to be invaluable for debugging. I have a very complex script that itself provides an API, and there's a lot of control flow complexity. Ideally it would be written in Go or something, but none of those languages provide the convenience of shell scripting for running other commands.