Today, I correct my mistake that i have done last day. Last night, when I turn off my laptop, my robotic vision presenatation on experimental server was lost. Its link did not work http://188.8.131.52:8990/robo_lec3.md#/. Because I was use tmux at wrong place. I run tmux before login into experimental, thats why, When I turn off laptop ,it lost. Today I did oposite. Firstly , I login into experimental and after that I run tmux and run prsentation from public_html folder of experimental. It works. Then I deattach tmux by typing ctrl+b, then d. Now presentation is accessible. tmux is a terminal multiplexer. We can save work , done on another terminal.