FIT SKJ printline

#!/bin/bash

#test if 3 arguments were specified
if [[ $# != 3 ]]
then
    exit 1;
fi

#test if $3 is readable file
if [[ ! -r "$3" || ! -f "$3" ]]
then
    exit 2;
fi

#test if $1 is positive number
if [[ ! $1 =~ ^([1-9][0-9]*|0)$ ]]
then
    exit 2;
fi

#test if $2 is positive number
if [[ ! $2 =~ ^([1-9][0-9]*|0)$ ]]
then
    exit 2;
fi

#test if $2 is at least $1
if [ $2 -lt $1 ]
then
    exit 2;
fi

#test if file have enough lines
lines=$(wc -l "$3" | awk '{print $1}')
if [ $lines -lt $2 ]
then
    exit 2;
fi

#print desired lines
awk -v from=$1 -v to=$2 '{if (NR >= from && NR <= to) print $0;}' "$3"
exit 0;