Multi-Application (multi-task) switching of the embedded Linux system on the command line (Terminal interface)

In the near future, some projects of multi-application (multi-task) Switching in the command line (Terminal interface) of the embedded Linux system need to run multiple applications at the same time, but I have no idea about this. I always understand it in a fragmented manner. In the past, I had no progress because I had not summarized it comprehensively. Write down what you have learned and add it at any time. If you see this article and find that my understanding is incorrect, please correct it. Involved shell command: fg bg jobs ps kill in the command line interface, if you need an application to run in the back header, enter./testapp1. At this time, the application testapp1 may output some debugging information, but you can continue to input shell commands. If you want to add more applications to run in the background, enter./testapp2. To view how many applications are currently running in the background, enter jobs and workers to display all applications running in the background. You need to switch the application and use the fg and bg commands. Fg switches the application to the foreground, and bg switches the currently running program to the background to continue running. For example, fg % 1; bg % 2. If it is a manual operation, when running an application, You Can Ctrl + z to make the current application suspended, not running. If you need to change the application to run in the background, enter bg % 1. If you want to terminate an application running in the background, use kill. The PID of the application can be obtained through the ps command.