split.sh

#!/bin/bash

# create sample file
original=original.txt
rm -f $original
touch $original

for x in $(seq 100); do
	echo $x >> $original
done

# split file
total_lines=$(wc -l $original | awk '{ print $1 }')
lines_per_file=10

number_files=$((total_lines / lines_per_file))
if [ $((total_lines % lines_per_file)) -ne 0 ]; then
	number_files=$(($number_files + 1))
fi

for x in $(seq $number_files); do
	start=$(((($x - 1) * $lines_per_file) + 1))
	end=$(($start + $lines_per_file - 1 ))
	output=$x.txt
	sed -n "${start},${end}p" $original > $output
done