capture standard out, standard error and return code in bash

stdout-stderr-rtncode-in-bash.sh

# #!/bin/bash
# 
# based on posts from stackexchange:
# http://stackoverflow.com/a/26827443/171475
# http://stackoverflow.com/a/18086548/171475
# http://stackoverflow.com/a/28796214/171475

function example_function {
    printf 'example output to stdout %d\n' {1..10}
    echo >&2 'example output to stderr'
    return 42
}



##############################
### using the dot operator ###

if [ "${BASH_VERSINFO}" -lt 4 ]; then
	printf '%s\n' "The source version of this script requires Bash v4 or higher."
else

	# stdout & stderr only
	source <({ cmd_err=$({ mapfile -t cmd_out < <(example_function); } 2>&1; declare -p cmd_out >&2); declare -p cmd_err; } 2>&1)
	
	printf "\n%s\n" "SOURCE VERSION : STDOUT & STDERR ONLY"
	printf "%s\n" "${cmd_out[@]}"
	printf "%s\n" "${cmd_err}"

	unset cmd_out
    unset cmd_err


	# stdout & stderr only as well as return code:
	source <({ cmd_err=$({ mapfile -t cmd_out< <( \
	    example_function \
	  ; cmd_rtn=$?; declare -p cmd_rtn >&3); } 3>&2 2>&1; declare -p cmd_out >&2); declare -p cmd_err; } 2>&1)
	

	printf "\n%s\n" "SOURCE VERSION : STDOUT, STDERR & RETURN CODE"
	printf '%s\n' "${cmd_out[@]}"
	# alternative version
	# declare -p cmd_out 
	printf '%s\n' "${cmd_err}"
	printf '%s\n' "${cmd_rtn}"

	unset cmd_out
    unset cmd_err
    unset cmd_rtn

fi

##############################
######### using exec #########

# stdout & stderr only
eval "$({ cmd_err=$({ cmd_out=$( \
	example_function \
  ); } 2>&1; declare -p cmd_out >&2); declare -p cmd_err; } 2>&1)"

printf "\n%s\n" "EVAL VERSION : STDOUT & STDERR ONLY"
printf '%s\n' "${cmd_out}"
printf '%s\n' "${cmd_err}"
printf '%s\n' "${cmd_rtn}"

unset cmd_out
unset cmd_err

# stdout & stderr only as well as return code:
eval "$({ cmd_err=$({ cmd_out=$( \
	example_function \
  ); cmd_rtn=$?; } 2>&1; declare -p cmd_out cmd_rtn >&2); declare -p cmd_err; } 2>&1)"


printf "\n%s\n" "EVAL VERSION : STDOUT, STDERR & RETURN CODE"
printf '%s\n' "${cmd_out}"
printf '%s\n' "${cmd_err}"
printf '%s\n' "${cmd_rtn}"


unset cmd_out
unset cmd_err
unset cmd_rtn