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bg – Move a Foreground Terminal Job to Run in the Background

The bg command is a built-in Linux command that is used to move a foreground process to run in the background. When you start a command or process in the terminal, it runs in the foreground, which means that it takes control of the terminal until it is completed or terminated. If you want to run a process in the background while still using the terminal for other tasks, you can use the bg command to move the process to run in the background.

Overview

The bg command is used to move a foreground process to run in the background. The syntax for the bg command is as follows:

bg [job_spec]

The job_spec argument specifies the job that you want to move to the background. You can specify the job using its job ID or its process ID. If you do not specify a job_spec, the bg command will move the most recently stopped job to the background.

To use the bg command, you first need to start a process or command in the terminal. For example, you can start a long-running process like rsync:

rsync -avh /path/to/source /path/to/destination

While the rsync command is running, you can press CTRL-Z to suspend the process and return control of the terminal to the shell prompt. You can then use the bg command to move the rsync process to run in the background:

bg %1

In this example, %1 is the job ID of the rsync process. You can also use the process ID to specify the job:

bg 1234

In this example, 1234 is the process ID of the rsync process.

Once you have moved a process to run in the background, you can continue to use the terminal for other tasks. You can view the status of background jobs using the jobs command:

jobs

This will show you a list of all active jobs, including their job ID, status, and command.

Options

The bg command does not have any options.

Troubleshooting tips

If you are having trouble moving a process to run in the background with the bg command, here are some troubleshooting tips:

  • Make sure that you have suspended the process using CTRL-Z before using the bg command.
  • Check the output of the jobs command to make sure that the job ID or process ID you are using is correct.
  • If the process is not responding, you may need to terminate it using the kill command before starting it again.

Notes

  • The bg command only works with processes that have been suspended using CTRL-Z. If a process is running in the foreground and you want to move it to the background, you will need to suspend it first using CTRL-Z.
  • When a process is running in the background, its output will not be displayed in the terminal. If you want to view the output of a background process, you can redirect its output to a file or use the fg command to bring it back to the foreground.

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