Fulcrum PDF reports are named with the record's unique fulcrum_id. This bash script loops through the parent CSV file and renames the PDF files based on the index of user-specified fields.

fulcrum-report-rename.sh

#!/bin/bash
INPUT=fire_hydrants.csv
OLDIFS=$IFS
IFS=,
[ ! -f $INPUT ] && { echo "$INPUT file not found"; exit 99; }
while read -a csv_line
do
	mv ${csv_line[0]}.pdf ${csv_line[8]}-${csv_line[0]}.pdf
done < $INPUT

windows-cmd-rename.txt

FOR /F "usebackq tokens=1,2,26 delims=," %a IN (fire_hydrants.csv) DO ren %a.pdf "%c.pdf"