#!/bin/bash -

#
# Use bash in the coprocess but turn off buffering
#
process='stdbuf -i0 -o0 -e0 bash'

#
# Indexed array of bash commands
#
declare -a com=('date +%F' 'whoami' 'id' 'echo "$BASH_VERSION"'
    'printf "Hello\nWorld\n"')

#
# Count commands in the array
#
n="${#com[@]}"

#
# Start the coprocess
#
coproc child { $process; }

#
# Loop though the commands
#
i=0
while [[ $i -lt $n ]]; do
    # Show the command
    echo "\$ ${com[$i]}"

    # Send to coprocess
    echo "${com[$i]}" >&"${child[1]}"

    # Read a line from the coprocess
    read -u "${child[0]}" -r results

    # Show the line received
    echo "$results"

    ((i++))
done

#
# Send an EOF to the coprocess (if needed)
#
if [[ -v child_PID ]]; then
    echo "-- End --"
    exec {child[1]}>&-

    # Flush any remaining results
    cat <&"${child[0]}"
fi