Linux terminal run in background

How can I put the current running linux process in background? [closed]

I have a command that uploads files using git to a remote server from the Linux shell and it will take many hours to finish. How can I put that running program in background? So that I can still work on shell and that process also gets completed?

The command is already running so i dont have other option. I am not sure which command to try. i didn’t wanted to break the current process so i didn’t experimented it

We should wait a more professional answer then 🙂 I meant if you had the chance to start all over again. ( The command & thing)

The accepted answerer on this question explains the three steps which needs to be taken: stackoverflow.com/questions/625409/…

You can also just open a second instance of putty and connect to the server again to get another shell. Though the solution with ctrl+z is great.

1 Answer 1

Suspend the process with CTRL+Z then use the command bg to resume it in background. For example:

sleep 60 ^Z #Suspend character shown after hitting CTRL+Z [1]+ Stopped sleep 60 #Message showing stopped process info bg #Resume current job (last job stopped) 

More about job control and bg usage in bash manual page:

JOB CONTROL
Typing the suspend character (typically ^Z, Control-Z) while a process is running causes that process to be stopped and returns control to bash. [. ] The user may then manipulate the state of this job, using the bg command to continue it in the background, [. ]. A ^Z takes effect immediately, and has the additional side effect of causing pending output and typeahead to be discarded.

bg [jobspec . ]
Resume each suspended job jobspec in the background, as if it had been started with &. If jobspec is not present, the shell’s notion of the current job is used.

To start a process where you can even kill the terminal and it still carries on running

nohup [command] [-args] > [filename] 2>&1 & 

nohup /home/edheal/myprog -arg1 -arg2 > /home/edheal/output.txt 2>&1 & 

To just ignore the output (not very wise) change the filename to /dev/null

To get the error message set to a different file change the &1 to a filename.

In addition: You can use the jobs command to see an indexed list of those backgrounded processes. And you can kill a backgrounded process by running kill %1 or kill %2 with the number being the index of the process.

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How to Run Linux Commands in Background and Detach in Terminal

In this guide, we shall bring to light a simple yet important concept in process handling in a Linux system, which is how to completely detach a process from its controlling terminal.

When a Linux process is associated with a terminal, two problems might occur:

1. Your controlling terminal is filled with so much output data and error/diagnostic messages.
2. In the event that the terminal is closed, the process together with its child processes will be terminated.

To deal with these two issues, you need to totally detach a process from a controlling terminal. Before we actually move to solve the problem, let us briefly cover how to run processes in the background in Linux.

Run Linux Command or Process in Background

If a process is already in execution, such as the tar command example below, simply press Ctrl+Z to stop it then enter the command bg to continue with its execution in the background as a job.

You can view all your background jobs by typing jobs . However, its stdin, stdout, and stderr are still joined to the terminal.

$ tar -czf home.tar.gz . $ bg $ jobs

You can as well run a Linux process in the background using the ampersand, & sign.

$ tar -czf home.tar.gz . & $ jobs

Take a look at the example below, although the tar command was started as a background job, an error message was still sent to the terminal meaning the process is still connected to the controlling terminal.

$ tar -czf home.tar.gz . & $ jobs tar: ./.config/etcher: Cannot open: Permission denied 

Keep Linux Process Running After Logout

We will use the disown command, which is used after the process has been executed and put in the background, its work is to remove a shell job from the shell’s active list jobs, therefore you will not use fg , bg commands on that particular job anymore.

In addition, when you close the controlling terminal or log out, the job will not hang or send a SIGHUP to any child jobs.

Let’s take a look at the below example of using the diswon bash built-in function.

$ sudo rsync Templates/* /var/www/html/files/ & $ jobs $ disown -h %1 $ jobs

You can also use the nohup command, which also enables a process to continue running in the background when a user exits a shell.

$ nohup tar -czf iso.tar.gz Templates/* & $ jobs

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Detach a Linux Process From Terminal

Therefore, to completely detach a process from a controlling terminal, use the command format below, this is more effective for graphical user interface (GUI) applications such as Firefox:

In Linux, /dev/null is a special device file that writes off (gets rid of) all data written to it, in the command above, input is read from, and output is sent to /dev/null.

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As a concluding remark, provided a process is connected to a controlling terminal, as a user, you will see several output lines of the process data as well as error messages on your terminal. Again, when you close the controlling terminal, your process and child processes will be terminated.

Importantly, for any questions or remarks on the subject, reach us by using the comment form below.

Aaron Kili is a Linux and F.O.S.S enthusiast, an upcoming Linux SysAdmin, web developer, and currently a content creator for TecMint who loves working with computers and strongly believes in sharing knowledge.

Each tutorial at TecMint is created by a team of experienced Linux system administrators so that it meets our high-quality standards.

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10 thoughts on “How to Run Linux Commands in Background and Detach in Terminal”

Hey, Thanks for this little Linux tip, useful for me to make my Linux commands run in the background… Reply

Without the “disown” you’ll get the following output in the source terminal after the given program is closed: “[1]+ Done firefox /dev/null” This only happens the next time something is put out to the terminal’s output stream. So, the next time command runs that writes to the output stream. To test this, run it without “disown”, close firefox, and then run “ls”. Reply

I see this is an old post but I think my question is sort of in the ballpark. what I would like to do is open the console of the process that was started with systemd with a no GUI flag. what this pertains to the Minecraft server. so I made a systemd service file and the execution command is “java -jar server.jar nogui” now once the system is up and running, I would like to open the GUI or console of the Minecraft server to issue commands without having to open a Minecraft launcher like you would play the game. I know I have done something like this in the past on other platforms but I just don’t know enough about Minecraft/java to make this happen. I am using ubuntu 18.04 and the current version of the Minecraft is 1.15.2 Reply

How to see the jobs running in the previous session? I have submitted jobs in nohup and logged out. After logging again if i wanna see the jobs and if I wanna kill, how to do so Reply

@Bala You can run this command:
ps -fu username #replace username with your real username
OR
ps -x Reply

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How to Run Bash Commands in the Background in Linux

There’s nothing more annoying than running a command in your terminal and having it run for minutes, sometimes hours, and not be able to use your terminal again. Sure, you can use tabs, but that’s a clunky solution, and it’s not always optimal because you may want to see updates as you’re working. Here we show you a few different ways to run bash commands in the background in Linux.

End a Command with &

If you want to push a command into the background, using & at the end is an easy way to do that. This way, you can issue a command in the background and continue to use your terminal as it runs. It comes with a catch, though. Using & doesn’t disconnect the command away from you; it just pushes it into the background. This means that while you’re trying to use the terminal, anything the command wants to push to STDOUT or STDERR will still be printed, which may be distracting.

When the terminal session is closed, the command ends. You can also kill the command by issuing the jobs command, finding the number of the command that’s running, and killing it with the kill command. That syntax is as follows:

Using & is good if you need to push something off for a bit but don’t expect it to continue forever.

& After a Command, Then Disown It

Running a command with just & pushes it off to the back and keeps it running as long as the terminal window is open. If, however, you’re looking to keep this command running in constant, even with your terminal session ending, you can use the disown command.

To use this method, start by adding an & .

As mentioned above, using & pushes this command into the background but doesn’t detach it from your user. You can verify this by typing jobs into the terminal. It’ll show the command running in the background as we saw before.

Just type disown into the shell, and it’ll do just that. (And you can once again verify this with the jobs command.)

Now you can close your terminal and continue about your day. It’ll still keep piping things to STDOUT or STDERR , but once you exit and reopen your terminal, you won’t see anything there. You can find the command again with the top or ps commands and kill it with the kill command.

& After a Command with /dev/null

Adding & after a command will push a command into the background, but as a result, the background command will continue to print messages into the terminal as you’re using it. If you’re looking to prevent this, consider redirecting the command to /dev/null .

This does not prevent the command from closing when the terminal closes. However, as mentioned above, it’s possible to use disown to disown the running command away from the user. You can also kill it in either of the methods mentioned above if you don’t want it to run anymore.

Nohup, with & and /dev/null

Unlike the previous commands, using nohup allows you to run a command in the background and keep it running. How? nohup bypasses the HUP signal (signal hang up), making it possible to run commands in the background even when the terminal is off. Combine this command with redirection to “/dev/null” (to prevent nohup from making a nohup.out file), and everything goes to the background with one command.

Most terminal programs on Linux today have features built in to allow them to run in the background with little effort. Along with that, modern init systems (like systemd) can allow users to start programs like services at boot or whenever.

Still, some programs on Linux lack the ability to run as a daemon or integrate with modern init systems. This is a real inconvenience but is understandable, as not all developers have the skill or time to add new features.

Luckily, commands like nohup or disown are still a reality and can close the gap in moving programs like this to the background. They’re not perfect or fancy, but they get the job done when needed.

If you enjoyed this Linux article, make sure to check out some of our other Linux content, like how to connect your Google account to GNOME Shell, the best Linux distros for windows users, and LS commands you need to know.

John is a young technical professional with a passion for educating users on the best ways to use their technology. He holds technical certifications covering topics ranging from computer hardware to cybersecurity to Linux system administration.

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