Mastering Application Management on Linux: Suspend and Resume with Ease

Linux users often encounter situations where they need to pause and resume applications without shutting them down completely. Fortunately, there are several effective methods to achieve this, primarily using the well-known kill command and the user-friendly htop task manager. This article will explore how to leverage both tools for effective process management in a Linux environment.

Identifying an Application’s Process ID (PID)

Before you can suspend or resume an application, the first step is to ascertain its Process ID (PID). This is critical, as the PID is a unique identifier for each running process on your system. The command ps aux is an essential utility for this purpose.

For example, if you want to find the PID of the “VirtualBox” application, run the following command:

ps aux

If you have many applications running, you can streamline your search by using the grep command:

ps aux | grep "VirtualBox"

The output will display a list of processes, with the PID appearing in the first column. In the case of VirtualBox, if the PID is listed as “10868,” you now have the identifier needed for further commands.

Suspending a Running Application with the kill Command

To suspend an application, the kill command is your go-to tool, specifically with the -STOP modifier. Ensure you have already identified your application’s PID. Let’s illustrate this with VirtualBox.

After confirming the PID:

kill -STOP 10868

By executing this command, the application enters a suspended state, ceasing all activity while remaining visible on your screen. It no longer consumes CPU resources until you decide to resume it.

Resuming a Suspended Application

When you are ready to revive a suspended application, you utilize the same kill command but this time with the -CONT modifier. First, confirm the PID of the suspended process:

ps aux | grep "VirtualBox"

Next, resume the application using its PID:

kill -CONT 10868

Executing this command will restore the application to its previous state, allowing it to function as before.

Simplifying Process Management with htop

While using the kill command is efficient, it may not be the most intuitive method for everyone. For a more user-friendly approach, consider using htop, a powerful terminal-based process viewer.

Installing htop

Before starting, check if htop is already installed by simply running:

htop

If it’s not available, you can easily install it using the following commands depending on your Linux distribution:

• Ubuntu/Debian:

  sudo apt install htop

• Arch Linux:

  sudo pacman -S htop

• Fedora:

  sudo dnf install htop

• OpenSUSE:

  sudo zypper in htop

Using htop to Suspend and Resume Applications

Launch htop by typing:

htop

With htop running, navigate through the list of ongoing processes using the UP and DOWN arrow keys. You can also press F3 to search for a specific application easily.

Once you locate the desired process, press F9 to open the "kill" menu. From here, select “19” (SIGSTOP) to suspend the program by hitting Enter.

To resume the suspended application, again press F9, and this time select “18” (SIGCONT). This action will successfully resume the process, allowing it to continue its tasks seamlessly.

Conclusion

Managing applications effectively in Linux requires an understanding of how to suspend and resume processes. Whether you choose the command line with kill or take advantage of the user-friendly htop, both methods empower you to optimize your workflow without closing applications entirely. With practice, these tools will become invaluable assets in your Linux toolkit.