split [-l line_count] [-b byte_count] [-n chunk_count] [file [prefix]]
split -l 100000 -d filename.csv file_
for i in $(find file_*); do mv $i "$i.csv"; done
for i in $(find . -type f -name "file_*.csv" -not -name "file_00.csv");
do echo -e "$(head -1 file_00.csv)\n$(cat $i)" > $i;
done