For me, educational stuff was all windows with a small amount of macs and I don't think I ever saw a Linux system in actual use anywhere.
Linux systems started being common in CompSci schools around mid-90s, around the time LAMP took off (fun fact, Apache, MySQL and PHP were all launched in 1995).
Previously in CompSci you'd get to use all kinds of UNIX servers. My uni still had Solaris servers with dumb terminals, and I got my first sysadmin certification on SCO.UNIX / OpenServer.
I still have Loki's port of Rune around somewhere.