source and export diff
Non-interactive shells don’t load initialization files, so bash -c ‘declare -f’ doesn’t output anything. But we can source it: bash -c ‘source ~/.bashrc; hello’. Or even: bash -c ‘hello() { echo “hi”; }; declare -f’. It’s all about memory share in shell modes: source changes only affect current shell memory. export marks variables to be passed to child processes. Subtile difference that can save us a lof of debugging time.