使用物理监视器运行 Pi 效果很好。但如果没有 HDMI 连接，NoMachine 无法找到任何正在运行的显示器。尝试service lighdm start通过 ssh 启动 lightdm 也不起作用systemctl。我收到下一个错误：
● lightdm.service - Light Display Manager
Loaded: loaded (/lib/systemd/system/lightdm.service; indirect; vendor preset: enabled)
Active: failed (Result: exit-code) since Thu 2021-09-23 16:55:28 IDT; 8s ago
Docs: man:lightdm(1)
Process: 1702 ExecStartPre=/bin/sh -c [ "$(cat /etc/X11/default-display-manager 2>/dev/null)" = "/usr/sbin/lightdm" ] (code=exited, status=0/SUCCESS)
Process: 1704 ExecStart=/usr/sbin/lightdm (code=exited, status=1/FAILURE)
Main PID: 1704 (code=exited, status=1/FAILURE)
Sep 23 16:55:28 raspberrypi systemd[1]: lightdm.service: Service RestartSec=100ms expired, scheduling restart.
Sep 23 16:55:28 raspberrypi systemd[1]: lightdm.service: Scheduled restart job, restart counter is at 5.
Sep 23 16:55:28 raspberrypi systemd[1]: Stopped Light Display Manager.
Sep 23 16:55:28 raspberrypi systemd[1]: lightdm.service: Start request repeated too quickly.
Sep 23 16:55:28 raspberrypi systemd[1]: lightdm.service: Failed with result 'exit-code'.
Sep 23 16:55:28 raspberrypi systemd[1]: Failed to start Light Display Manager.
Sep 23 16:55:28 raspberrypi systemd[1]: lightdm.service: Triggering OnFailure= dependencies.