If you were a productive unix sysadmin in 2008 you are a productive unix sysadmin in 2018. Its just that Linux is no longer unix-like and you've switched from using, perhaps, Debian install media in '08 to FreeBSD install media in '18. Its not really that big of a problem. Its much easier and more productive to switch to FreeBSD than to switch to ... whatever it is Linux is becoming.
> If you were a productive unix sysadmin in 2008 you are a productive unix sysadmin in 2018.
Unless you mention Perl to someone now, and that someone might be 10 years younger but still your manager, and they look at you like you just spoke greek.
Ha ha! Perl has become the shit test for whether I feel like dealing with certain people. "Oh, you don't use Perl?...." Not everyone, just certain ones.