Cheatsheet Pages / systemd Cheatsheet
How to see a unit exactly as systemd sees it — systemctl cat
The file on disk and what systemd actually loaded differ — drop-ins included, this prints the merged truth.
Most management commands need sudo, and systemctl only works on a system actually booted with systemd — inside containers it fails with “System has not been booted with systemd as init system”. Every command was checked against systemd 255, and the example units pass systemd-analyze verify.
systemctl cat nginx # base file + every drop-in merged, each piece labelled with its file path
# this is the ground truth — what you edited is not always what is running