How to run multiple background jobs?

Running Multiple Background Jobs in Linux

In the Linux operating system, you can run multiple tasks or commands in the background, allowing you to continue using the terminal or command prompt for other tasks. This is particularly useful when you have long-running processes that don't require immediate attention, or when you want to execute multiple tasks simultaneously.

Understanding Background Jobs

In Linux, when you run a command, it typically runs in the foreground, occupying the terminal until the command completes. However, you can send a command to run in the background by appending an ampersand (&) at the end of the command. This allows you to continue using the terminal while the background job runs.

Here's an example of running a command in the background:

$ sleep 60 &
[1] 12345

In this case, the sleep 60 command will run in the background, and the terminal will return the job number ([1]) and the process ID (12345) of the background process.

Listing and Managing Background Jobs

Once you have started a background job, you can use the following commands to manage and interact with it:

1. jobs: This command lists all the background jobs currently running in the terminal session.

$ jobs
[1]+ Running    sleep 60 &

2. fg: This command brings a background job to the foreground, allowing you to interact with it directly.

$ fg %1
sleep 60

3. bg: This command resumes a suspended background job, allowing it to continue running in the background.

$ sleep 120 &
[2] 12346
$ jobs
[1]- Running    sleep 60 &
[2]+ Stopped    sleep 120
$ bg %2
[2]+ sleep 120 &

4. kill: This command can be used to terminate a background job.

$ kill %1
[1]+ Terminated    sleep 60

Practical Examples

Let's consider a few practical examples of running multiple background jobs in Linux:

1. Downloading multiple files: Suppose you need to download several large files from the internet. You can start each download in the background using the & operator, allowing you to continue using the terminal for other tasks.

$ wget https://example.com/file1.zip &
$ wget https://example.com/file2.zip &
$ wget https://example.com/file3.zip &

2. Running long-running backups: If you need to perform a backup of your system, you can run the backup process in the background, freeing up the terminal for other tasks.

$ tar -czf backup.tar.gz /home /etc &
[1] 12347

3. Executing multiple build or deployment tasks: When working on a software project, you may need to run multiple build or deployment tasks. By running these tasks in the background, you can speed up the overall process and continue working on other aspects of the project.

$ make clean && make -j4 &
$ ansible-playbook deploy.yml &

In the above example, the make command to clean and build the project, and the Ansible playbook to deploy the application, are both running in the background.

By understanding how to run and manage background jobs in Linux, you can become more efficient and productive in your daily tasks, allowing you to multitask and work on multiple things simultaneously.