How to script that multiple commands outputs are shown real-time?

Question

I'd like to run a few commands simultaneously and observe their output in real-time. Ideally it would be an automatic bash script which runs commands c1, c2, c3 at the same time and shows them in a grid view in a single terminal.

How can I achieve that the easiest way?

I've seen that screen could do something like that, but I'm not sure how to put that together. I'm using KDE Plasma, so I suppose I need to run that script with konsole. The commands are not always the same, so I need to parametrize them.

Answer 1

Very simplest:

ESSENTIAL First, BASIC requirement:
Make sure each command does a SINGLE quick update, prints the result and EXITS after that.

Create a text file with this content, save as e.g. observer.sh

rev="$(tput rev)"
off="$(tput sgr0)"

while true ; do 

  tput reset; 
  date; 

  echo -e "$rev--- c1 ---$off"; 
  # command c1 here

  echo -e "$rev--- c2 ---$off"; 
  # command c2 here

  echo -e "$rev--- c3 ---$off"; 
  # command c3 here

  sleep 1; 
done

Start it with bash observer.sh
The script, as is above, shows a rolling date/time at top, 1 second update.

To get the output in "a grid" is quite a bit harder; it involves manipulating the output window with e.g. ncurses commands via e.g. tput AND setting and retaining stdin, stdout and stderr for each command connected to each a separate ncurses-window - similar to what Bash does as it starts a command.

Note: https://stackoverflow.com/q/47502223/3720510 indicates that this isn't an easy task

But then: https://github.com/metal3d/bashsimplecurses
Simple examples: https://www.youtube.com/watch?v=MEULy6oqrfM