When Sysadmins Ruled The Earth by Cory Doctorow

After a sudden, civilization‑collapsing event leaves most people dead, a handful of system administrators find themselves among the few with the skills to keep networks, power, and critical data running; they scavenge and repair hardware, rig solar power, and use their command-line expertise to reconnect scattered survivors, while facing wrenching ethical choices about who to help, how to allocate scarce resources, and what it means to rebuild society when technical stewardship becomes the closest thing to leadership.