printf '\xEF\xBB\xBF' >bom.dat find . -name '*.csv' \ -exec sh -c 'head --bytes 3 {} | cmp --quiet - bom.dat' \; \ -print
Could be made into a oneliner by replacing the 'bom.dat' argument to cmp with '<(printf ...)'.
-n, --bytes=LIMIT compare at most LIMIT bytes
find . -name '*.csv' -type f -exec cmp -sn 3 {} bom.dat \; -print
Could be made into a oneliner by replacing the 'bom.dat' argument to cmp with '<(printf ...)'.