How to bring a background process to the foreground

You can switch tasks through job control in the terminal without opening a new tab or reconnecting. The specific method is as follows: 1. Use the jobs command to view the tasks currently running in the background; 2. Call the specified task back to the foreground through fg % task number; 3. If there is no task number, use ps aux | grep to find the process PID and use kill -CONT to resume running; 4. To suspend the foreground process, use Ctrl Z, then enter bg to put it into the background, jobs to confirm the status, and fg to return to the foreground. Proficiency in these commands can improve the efficiency of terminal operations.

Sometimes you run a command in the terminal and it occupies the current window, but you don't want to open a new terminal tab or disconnect and reconnect. At this time, putting the process in the background and then bringing it back to the foreground can solve the problem.

Linux and macOS terminals support job control, which allows you to switch tasks without closing the program. The key is the bg , fg and jobs commands.

View processes currently running in the background

If you have put a process in the background before and want to bring it back, the first step is to confirm that it is indeed running in the background. You can use:

 jobs

This command will list all pending or background tasks in the current shell session. You will see output similar to this:

 [1] Running sleep 300 &

[1] here is the task number, and the following Running indicates that it is running, not suspended.

Bring the background process to the foreground

After confirming the task number you want to bring back to the front desk, use the fg command plus the task number to bring it back:

 fg%1

Here %1 represents the job with task number 1. Once executed, the task will reoccupy your terminal window just as if you had run it directly in the first place.

• If you only have one background task, you can directly enter fg without parameters.
• If there are multiple tasks, it is recommended to specify the number clearly to avoid misoperation.

No task number? Try ps and kill

If jobs do not list anything, these tasks may not have been started by the current shell, or they may have been started through a script. At this time you have to use a more general method to check the process:

 ps aux | grep "keyword"

After finding the corresponding PID (process ID), you can use kill -CONT <pid></pid> to continue the process, but note: it will not automatically return to the current terminal, it will just continue running.

If you want to "connect" it back to the current terminal, you may have to rely on tools such as reptyr or screen / tmux .

Tips: Tips for suspending and putting in the background

• To temporarily interrupt a foreground process, press Ctrl Z and it will be suspended;
• Then enter bg and it will run in the background;
• Enter jobs again to confirm the status;
• Finally use fg to adjust it back.

Used together, these commands can allow you to switch tasks efficiently in the terminal without frequently opening new windows.

That's basically it. If you master it proficiently, your daily operations will be much smoother.

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