tmux is allowed in CKAD

 Therefore I needed to learn tmux. main commands below

• Ctrl+b " — split pane horizontally.
• Ctrl+b % — split pane vertically.
• Ctrl+b arrow key — switch pane.
• Ctrl+b : - enter command mode, "setw -g mouse" <-to enable mouse scroll in tab 

looks nice

check https://cloudacademy.com/blog/micro-blog-1-of-3-what-i-wish-i-knew-before-i-took-the-ckad-multi-what/