backtrace working fine!

lib/backtrace.bash

@@ -21,11 +21,13 @@ function exit {
   # # remove 0 on tail list
   # [[ ${#stack_lines[@]} > 0 && ${stack_lines[-1]} == 0 ]] && unset stack_lines[-1]
 
+  rm $script
   if [[ $error_code > 0 ]]; then
     printf "\nEXIT #${error_code} due to error at line ${stack_lines[*]} : \n-----------------------------------------\n"
-    echo "FUNCNAME:    ${FUNCNAME[@]}" >&2 # inner outer main
-    echo "BASH_SOURCE: ${BASH_SOURCE[@]}" >&2
-    echo "BASH_LINENO: ${BASH_LINENO[@]}" >&2
+    [[ -s /tmp/error ]] && echo -ne 'CAUSE:\t\t' && cat /tmp/error
+    echo -e "FUNCNAME:\t${FUNCNAME[@]}" >&2 # inner outer main
+    echo -e "BASH_SOURCE:\t${BASH_SOURCE[@]}" >&2
+    echo -e "BASH_LINENO:\t${BASH_LINENO[@]}" >&2
     trap - ERR TERM INT EXIT
     builtin exit "${error_code}"
   else
@@ -41,8 +43,11 @@ function raise_error {
   exit $code
 }
 
+# MAIN
 _BACKTRACE=${_BACKTRACE:-false}
 # echo "_BACKTRACE=${_BACKTRACE}"
+
+# a bit of magic: preserve performing the original script and rather running the backtrace version
 ${_BACKTRACE} && return
 
 set -TEue
@@ -50,5 +55,23 @@ trap 'exit $?' ERR TERM INT EXIT
 # echo "current: ${BASH_SOURCE[-1]}"
 # echo "ARGV   : $@"
 export _BACKTRACE=true
-# exec ${BASH_SOURCE[-1]} $*
-eval $(<${BASH_SOURCE[-1]}) $*
+
+source=${BASH_SOURCE[-1]}
+script="${source}.backtrace"
+cp $source $script
+
+# prepend the set Strict command
+sed -i '1s/.*/set -TEue/' $script
+
+# a bit of magic: save stderr into /tmp/error while outputing stdout!
+{
+  $script 3>&1 1>&2 2>&3 | tee /tmp/error
+} 2>/dev/null >/dev/null
+
+# SOME VARIANTS (which does not work actually)
+# ----------
+# exec ${BASH_SOURCE[-1]} $* 2>/tmp/error
+# eval $(<${BASH_SOURCE[-1]}) $* 2>/tmp/error
+# eval $(<$script) $* 2>&1 >/tmp/error
+# $script $* 2>&1 >>/tmp/error
+# ERROR=$($script 3>&1 1>&2 2>&3 | tee /tmp/error)

test2.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env -S -- bash
+
+## MAIN
+. "lib/backtrace.bash"
+
+function f1 {
+  echo START f1
+  # return 4
+  # echo $nope
+  grep titi titi
+  grep titi titi 2>/dev/null
+  false
+  echo END F1
+}
+
+echo START test2
+f1
+echo END test2