bashfill

#!/bin/bash

# synopsis:  bashfill FILE ... [-- TEMPLATEOPTIONS ... ]

function include() {
    lastline=$(tail -n 1 $1; echo x);
    lastline=${lastline%x};
    sanitize='';
    [[ "${lastline: -1}" != $'\n' ]] && sanitize=$'\n';
    read; [[ "$REPLY" =~ ^'#!' ]] || {
    cat <(echo "$REPLY") - <(echo -n "$sanitize");
    } && cat - <(echo -n "$sanitize");
}

declare -a BASHFILL;

while [[ $1 != '--' ]] && [[ $# -gt 0 ]]; do
    BASHFILL[index++]=$1; shift;
done

[[ $1 == '--' ]] && shift;

source <(echo 'cat <<ENDOFASSEMBLY';
for (( order=0; order != index; ++order )); do
[[ -e "${BASHFILL[order]}" ]] && {
include "${BASHFILL[order]}" < "${BASHFILL[order]}";
} || { [[ -n "${BASHFILL[order]}" ]] &&
echo ${BASHFILL[0]}: error: unable to include $(pwd)/${BASHFILL[order]} >&2;
}; done; echo 'ENDOFASSEMBLY');