shell-读取电子书

#!/bin/bash
book=$1
read -p "input you want reader begin:" chapter
echo ====================================================================================

rownumber=$( cat ${book} |wc -l )
echo ${chapter}

nownumber=$(cat ${book} | grep -n ${chapter} | awk -F ':' '{print$1}')

tail -n +$nownumber ${book} | while read line
do
        echo "${line}"
        sleep 2
        clear
done

while [ $nownumber -lt $rownumber  ]
do
        nownumber=$((nownumber+1))
        echo ${nownumber}
        sleep 1
done