How to check the HDMI interface status after the boot

Hi
How to check the HDMI interface status after the boot, Check whether the HDMI interface is working properly

I am not sure what do you mean “HDMI interface is working properly”.

You can use /sys/devices/virtual/switch/hdmi/state to check if it is connected.

Thank you very mach!
I looked at the state values is 1, This 1 represents an HDMI interface or the state of the connection on?

Yes, it means connected.