This feature has been part of bash since 5.1 (ca 2020), though it may not be ena...

This feature has been part of bash since 5.1 (ca 2020), though it may not be enabled in all distros.

  cd src/bash-5.3/examples/loadables
  make accept
  enable -f ./accept accept
  (accept -r RHOST -v SOCKETFD -b 127.0.0.1 8000; 
    read -u $SOCKETFD SOCKETDATA; 
    printf "%s: %s\n" "$RHOST" "$SOCKETDATA";
    printf "goodbye, world\n" 1>&${SOCKETFD} ) &
  nc 127.0.0.1 8000 <<< "hello, world"

For real use you may need to add "exec {SOCKETFD}<&-" to close the FD.

Edit: https://hackertimes.com/item?id=39369749 (2024)