So, like how in Linux, a lot of system manipulation is presented as psuedo text files in /proc and and /sys, but expanded to the rest of the system. So like the window manager is manipulated by creating fake files (fake as in they don't exist in any persistent storage device) and writing text to them that describes the state of the windows. Rather than socket() and setsockopt(), under the hood it's opening something like /dev/net/tcp/google.com/80/ctrl and reading and writing text about the state of the connection.

Because of this the whole system is introspectable via cating interesting files.

Writing email. Viewing logs. Configuring servers. Setting reminders can be done in cron. Probably lots I don’t know about offhand too.