Thank you for your reply。
chmod -x /usr/sbin/lightdm
it worked, tx1 boot to command line.
When I execute the script following the content below
Hdmi displays a small white command-line window, and myapp has not been executed.
I know now is a little strange, in fact, is the first time I face in an embedded system running ubuntu.
My product requirements are：
1, multi-channel video decoding， four channel h264 or h265 decoded video splicing into one picture ,and show on hdmi screen. QT as a user interface program is also displayed in the hdmi output.
2, When the device starts, do not want to see ubuntu-related content displayed, including the startup information and desktop
Because I want to multi-channel display, so I envision the use of Xlib window concept, the use of four window display four channel video, so the easiest to achieve the stitching effect, so I need to run X service, but do not want to show ubuntu desktop, so I envisioned init process is to start X, and then start qt and other app.
Is there a way for me to use the simplest init method to configure my startup content. Start speed is not what I need to care about. I can provide some direction, thank you.