mail/mailx CMD // 메일전송
# mailx -s ' [ OK ] server1' admin@example.com < /root/report.txt
wall CMD
# wall < /etc/MESS/work.txt
[참고] 긴급 작업 절차
# touch /etc/nologin
# wall < /etc/MESS/work.txt
...
# fuser -cu /home
# fuser -ck /home
작업 진행
# rm -f /etc/nologin