A small shellscript to slice a file into several smaller files

slice.sh

#!/bin/bash

INPUT_FILE=$1
LINES_PER_FILE=$2

if [ -z $LINES_PER_FILE ]; then
    LINES_PER_FILE=1000
fi

if [ -z $INPUT_FILE ]; then
    echo "usage: $0 input_file [lines_per_file=1000]"
    exit 1
fi

if [ ! -f $INPUT_FILE ]; then
    echo "$INPUT_FILE could not be read"
    exit 1
fi

INPUT_LINES=`wc -l $INPUT_FILE | awk '{print $1}'` 

if [ $INPUT_LINES -lt $LINES_PER_FILE ]; then
    echo "input files has less than $LINES_PER_FILE lines"
    exit 0
fi

RESULT_FILES=$((($INPUT_LINES / $LINES_PER_FILE) + 1))

echo "slicing $INPUT_FILE into $RESULT_FILES $LINES_PER_FILE lines files "

for i in `seq $RESULT_FILES`; do
    echo "slicing file #$i"
    tail -n +$((($i - 1) * $LINES_PER_FILE)) $INPUT_FILE | head -n $LINES_PER_FILE > $INPUT_FILE.$i
done