http://ru.wikipedia.org/wiki/Less
http://ru.wikipedia.org/wiki/Tail
$ tail -n 5 /var/log/messages
$ kubectl -n portal get po | tail -n +2 | grep -v "postg" | awk '{print $1}' | xargs kubectl -n portal delete po
$ sudo tail -f -n 0 /var/log/auth.log
$ sudo tail -fn0 /var/log/auth.log | stdbuf -o0 grep abcd | while read L; do echo $L | mail -s abcd userX@isp.un; done