I attempted to log in today and discovered that I had more users than I thought. It seems that both MS-SQL and RStudio users exist on my PC and are visible on my log-in screen. I've ran SQL on my laptop before, but only in a localhost setup that let me learn the language. Is there any good reason why I should have these users or any good reason why I shouldn't get rid of them?
Note that id -u mssql returns 997 and id -u rstudio-server returns 998.
The users shown at the greeter need to be at minimum (and the maximum UID_MAX) what is set in /etc/login.defs at UID_MIN.
The range 1–499 (Red Hat, CentOS) or 1–999 (Debian, Ubuntu) are reserved for system users, including users allocated when installing a package containing a system service that requires a dedicated user.
So your mssql user having 997 is correct. That user should, in default Ubuntu, not be shown at the greeter when it is below 1000.
Please check what your minimum is set to. To get rid of user 997 one methoud should be changing that parameter to something above 997. If it is 1000 this is a bug and should be reported against the greeter you use.
