Print newly added lines from log file

#/bin/bash

logfile="linelog.log"

# remember the number of lines first
logcount_oldln=`wc -l < ${logfile}`
logcount_oldch=`wc -c < ${logfile}`

# do something and update the log
date "+%Y/%m/%d %H:%M:%S" >> ${logfile}
sleep 1
date "+%Y/%m/%d %H:%M:%S" >> ${logfile}
sleep 1
date "+%Y/%m/%d %H:%M:%S" >> ${logfile}

# check the diff
logcount_newln=`wc -l < ${logfile}`
logcount_newch=`wc -c < ${logfile}`
logcount_diffln=`expr ${logcount_newln} - ${logcount_oldln}`
logcount_diffch=`expr ${logcount_newch} - ${logcount_oldch}`
echo "added: ${logcount_diffch} bytes, ${logcount_diffln} lines"

# show it
#tail -n ${logcount_diffln} ${logfile}
tail -c ${logcount_diffch} ${logfile}