How To Background A Process In Linux

When working with graphical desktop environments, we rarely worry about background processes. If we have a process running in the foreground, we tin quickly spawn another terminal window and continue with our work.

However, if you are in a raw terminal shell such as SSH, you lot will often experience concerned about processes that occupy and block the crush until they are completed, especially on long-running jobs. That is where the concept of groundwork and foreground processes comes into play.

This tutorial will discuss what background and foreground processes are, including creating and managing them in Linux.

What is a Process?

Allow me to offset at the basic level: what is a process?

In Linux, a process is an instance of a program. Typically, this means any command or executable in a shell is a procedure.

At that place are mainly ii types of processes:

Foreground processes
Background processes

Foreground processes are mainly typical applications that we launch and interact with them. An example would exist the nautilus file manager in Gnome. In most cases, nosotros can start foreground processes from the shell or the desktop environment.

On the other hand, background processes run in the background and require no input or interaction from the user. An example would be whatever typical Linux daemon.

How to Run a Process in the Background

Suppose nosotros have a procedure that, while running, occupies the trounce session and hinders us from executing commands until it exits.

For example, if we run the Firefox browser in the shell, it will occupy the session until process termination.

As you can come across, every bit long equally Firefox is running, the trounce prompt is unavailable, and nosotros cannot execute any more than commands.

To solve this, we tin exercise it 2 ways:

one: Using an Ampersand (&)

The first method is using the ampersand & sign. This tells the shell to run whatsoever command precedes the ampersand in the groundwork.

An example:

In such a scenario, the process executes in the background and spawns as a new shell prompt allowing u.s. to go on executing commands.

It as well gives two numerical identifiers. The first one enclosed in foursquare brackets is the Job ID, while the adjacent one is the process ID.

2: Using CTRL + Z, bg command.

The next method you can use to put a process in the background is to use the shortcut CTRL + Z. This stops the process from blocking the shell. You can and then use the bg command to button it to the background.

For case, get-go by launching Firefox every bit:

While the process is running, press CTRL + Z. This returns your shell prompt. Finally, enter the bg command to push the process in the groundwork.

How to Show Background Processes

To view and manage processes in the background, use the jobs command in the shell. That will prove the groundwork jobs in the current terminal session.

For example:

An instance output of background jobs:

To bring a procedure running in the background to the foreground, use the fg command followed by the job id.

For example, to bring the firefox job in the foreground, we use the control:

To put in the background over again, press CTRL + Z followed by the bg command.

How to Make a Process Persistent After Shell Dies

When you are running processes in the groundwork, and your vanquish session dies, all the processes associated with it terminate, which can be problematic, particularly if it is an SSH session.

However, this is not likewise big an event if you use a concluding multiplexer such as tmux or screen because, in that case, you can but reattach the session.

Yet, if you run a beat out session without a multiplexer, you tin use the nohup command.

The nohup command is immune to hang-ups and tin ignore the SIGHUP bespeak sent to a procedure.

Hence, if y'all run a command with nohup, it continues to run even if the shell session accidentally dies.

For example, to run Firefox with nohup, use the command:

This will run the procedure in the background as persist a shell cease.

You can run a new terminal session and view the background jobs. Yous will see the process nevertheless running in the background.

Decision

In this tutorial, we discussed various ways to run and transport processes to the background in Linux. Nosotros also covered how to bring a background procedure to the background and persist hang-up upon shell termination.

About the author

My name is John and am a fellow geek like you. I am passionate near all things computers from Hardware, Operating systems to Programming. My dream is to share my knowledge with the world and help out boyfriend geeks. Follow my content past subscribing to LinuxHint mailing list