Running programs in background linux

The Complete Guide to Running Programs in the Background in Linux

Learn how to run programs in the background in Linux with this comprehensive guide. Discover tips, best practices, and common issues for managing background processes.

• Introduction
• Running Programs in the Background in Linux
• How to run a program in background in Linux
• Monitoring and Managing Background Processes in Linux
• Advantages and Disadvantages of Running Programs in the Background in Linux
• Tips and Best Practices for Running Programs in the Background in Linux
• Common Issues with Running Programs in the Background on Linux Systems
• Additional useful code snippets for running programs in the background on Linux
• Conclusion
• How do I run an application in the background in Linux?
• How do I run a program in the background in Unix?
• How do I run a program in the background?
• How to run C program in background Linux?

If you’re a Linux user, you know that running programs in the background is an essential skill. It allows you to keep your terminal session free while your program runs in the background so that you can continue working on other tasks without any interruptions. In this guide, we’ll be discussing the different ways to run programs in the background in Linux, how to manage them, their advantages and disadvantages, and some best practices to follow.

Introduction

Explanation of Linux background processes

Background processes are processes that run independently of the command shell. They don’t require any user input and run in the background without taking up your terminal window. This is useful when you need to run long processes that take a while to complete.

Importance of running programs in the background

Running programs in the background is crucial because it frees up your terminal window to execute more commands, and it allows you to run long processes without having to keep an eye on them constantly.

Overview of the key, important, and helpful points

This guide will cover the different ways to run programs in the background in Linux, how to manage them, their advantages and disadvantages, and some best practices to follow.

Running Programs in the Background in Linux

Using Ctrl + Z and bg command to send a process in the background

Explanation of the Ctrl + Z command

The Ctrl + Z command suspends the current process and sends it to the background. This command leaves the process in a suspended state, which means it’s not running but still exists in the system’s memory.

How to use bg command to send a process in the background

To send a suspended process to the background, you can use the bg command followed by the job ID. The job ID is a number that corresponds to the process that you want to send to the background.

Examples of using Ctrl + Z and bg command

Suppose you’re running a long process called my_long_process and want to send it to the background. To do this, you can use the following commands:

Using the disown command to run programs in the background

Explanation of the disown command

The disown command removes the job from the current shell’s job list, which means that it won’t receive a SIGHUP signal when the terminal session ends.

How to use the disown command to run programs in the background

To use the disown command, you need to first suspend the process using the Ctrl + Z command, followed by the bg command. Then, you can use the disown command to remove the process from the job list.

Examples of using the disown command

Suppose you’re running a long process called my_long_process and want to run it in the background using the disown command. To do this, you can use the following commands:

$ my_long_process ^Z $ bg $ disown 

Using the nohup command to run programs in the background after logging off

Explanation of the nohup command

The nohup command stands for “no hang-up.” It allows you to run a command or script in the background even after logging off. This command redirects the standard output and standard error to a file called nohup.out.

How to use the nohup command to run programs in the background

To use the nohup command, you need to prefix the command or script that you want to run with the nohup command.

Examples of using the nohup command

Suppose you want to run a script called my_script.sh in the background using the nohup command. To do this, you can use the following command:

Using the screen command to start a new “screen” and execute the command or script in the background

Explanation of the screen command

The screen command creates a new terminal session that can be detached from the current session. This allows you to continue running your program in the background even after logging off.

How to use the screen command to run programs in the background

To use the screen command, you need to first start a new screen session using the command screen , followed by the command or script that you want to run in the background.

Examples of using the screen command

Suppose you want to run a script called my_script.sh in the background using the screen command. To do this, you can use the following commands:

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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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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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