Resolve DOI references and print bibliography in BibTeX format

fetchbib.sh

#!/bin/bash
if [[ $# -lt 1 ]]; then
    echo "Usage ${0} <doi> ..."
    exit 1
fi

for doi in "${@}"; do
    ref="$(curl -sSf -H 'Accept: application/x-bibtex' -L "http://dx.doi.org/${doi}")" && { \
        head -n1 <<< "${ref}" | egrep -q '^@[a-zA-Z]+'
        if [[ $? != 0 ]]; then
            echo 'WARNING:' "${doi}" 'does not look like a BibTeX entry. Manual check is recommended.' 1>&2
        fi
        cat <<< "${ref}"
    }
    echo
done