$ wall System will go down in one hour Broadcast message from shs@stinkbug (pts/17) (Thu Sep 14 14:04:16 2017): System will go down in one hour
Important messages should probably be delivered through multiple channels as it's difficult to predict what users will actually notice. Together, message-of-the-day (motd), wall, and email notifications might stand of chance of getting most of your users' attention.
Paying attention to log files
Paying attention to log files can also help you understand user activity. In particular, the /var/log/auth.log file will show you user login and logout activity, creation of new groups, etc. The /var/log/messages or /var/log/syslog files will tell you more about system activity.
Tracking problems and requests
Whether or not you install a ticketing application on your Linux system, it's important to track the problems that your users run into and the requests that they make. Your users won't be happy if some portion of their requests fall through the proverbial cracks. Even a paper log could be helpful or, better yet, a spreadsheet that allows you to notice what issues are still outstanding and what the root cause of the problems turned out to be. Ensuring that problems and requests are addressed is important and logs can also help you remember what you had to do to address a problem that re-emerges many months or even years later.
Managing user accounts on a busy server depends in part on starting out with well configured defaults and in part on monitoring user activities and problems encountered. Users are likely to be happy if they feel you are responsive to their concerns and know what to expect when system upgrades are needed.
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