use sed (gsed for mac/homebrew) to insert a header into .csv files & remove BOM

script.sh

#!/bin/bash
for file in *.csv
do
    # 1i means insert before line 1
    gsed -i 1i"animals,numbers,colors" $file
    echo "inserted header in $file!"
    gsed -i "s/^\xef\xbb\xbf//" $file
    echo "removed BOM in $file!"
done