# The trick: Set Record Separator to nil, and Field Separator to newline.
# This capitalizes on the structure of how JabRef formats the database, where each entry is separated by a newline.
# The following command prints the first line of the record, which is the bibtex type field and the entry key.

BEGIN{RS=""; FS="\n"}

{print $1}

# Other possible options:
# {print $(NF)                 # This prints the last line (should be the closing curly bracket)
# {print $(NF - 1)             # This prints the last field before the closing curly bracket
# ($1 ~ "Almeida") {print $0}  # This would print all the entries that have "Almeida" as a key.