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The post How to Set Priority of a Running Process in Linux first appeared on Tecmint: Linux Howtos, Tutorials & Guides .In this article, we’ll briefly explain the kernel scheduler (also known as the process scheduler), and process priority, which are topics beyond the scope of The post How to Set Priority of a Running Process in Linux first appeared on Tecmint: Linux Howtos, Tutorials & Guides.View the full article

The htop is a CLI utility to check an interactive list of running processes in real-time. It is a more feature-rich and user-friendly alternative to the top command. The htop command allows you to manage system processes, monitor resources, and perform other administration tasks. One of the most prominent features of htop is that it shows color-coded processes, which helps you differentiate them based on resource usage. Furthermore, it lets you customize the results with its sort and filter options. So, this short tutorial is about how to use the htop command in Linux without hassles. Unlike top, the htop command is not preinstalled in most Linux systems. That’s why you must install it using the following commands: Operating System Command Debian/Ubuntu sudo apt-get install htop Fedora sudo dnf install htop RHEL/CentOS sudo yum install htop Now, you can use the htop command, so let’s start with the basics: htop When you execute the above command, it launches the htop utility. Here, you can use the arrow keys to navigate up and down the processes. Moreover, press ‘F1’ or ‘?’ to get the help screen for additional navigation shortcuts. Sort Processes in htop In htop, you can sort the processes by CPU, memory, and other usage. Open the sorting menu by pressing F6: For example, select the PERCENT_CPU option and press ‘Enter.’ As you can see in the above image, all the processes are now sorted by CPU consumption. Search and Filter Processes in htop To search any process in htop, please go through the following steps: Press ‘F3’ to open the search bar. Similarly, press ‘F4’ to filter out the processes. Additional Options with htop -d, –delay=[argument]: By default, htop updates the processes every second, but you can add a delay using this option. For instance, to introduce a delay of 10 seconds, we would enter ‘–delay=10.’ -C, –no-color: This option disables the color output, which is helpful in systems with limited terminal support for colors. -u, –user=[username]: To display the processes for a specific user. Just replace ‘[username]’ with the target user’s name. -p, –pid=[PID1,PID2]: Displays information for specified process IDs. For example, let’s check the details of PID 1: htop -p 1 -v, –version: Prints htop version information. -h, –help: This displays a help message with usage information. Kill a Process in htop If you want to kill any process, select it and press the ‘F9’ key or ‘k’ to transmit a kill signal for the selected process. Wrapping Up Htop is a powerful utility for interactively checking system processes in real time. This tutorial briefly discusses how to use the htop command. As htop is not a preinstalled utility in Linux distributions, your first step is to install it using the mentioned commands. Later, we explained how to sort, search, filter, and kill processes from the htop utility. View the full article

Processes are the running instances of programs that consume system resources. Listing these processes helps you monitor system activity, and troubleshoot issues. That’s why there are multiple tools and utilities in Linux that you can use to list the currently running process. However, many beginners don’t know the exact way to list the process without errors. So, in this short article, we will explain different methods to list the process in Linux. We have divided this section into multiple parts to give you the best commands to list the processes in Linux. The ps Command The ps, or “process status,” is the most common utility to list processes in the terminal: ps -e The -e option guides ps to show every process regardless of whether the user owns those processes. Furthermore, you can customize the ps command to produce additional details using the “aux” options: ps aux The top Command If you desire to view the real-time list of system processes, please use the top command. It continuously updates the process list according to new and completed processes, providing more accurate results: top The above command on execution shows the list of processes as per their CPU consumption. Moreover, You can not interact with the terminal until you press “q” to quit the top utility. The pstree Command The pstree is very different from the above two commands because it displays the hierarchical relationship of processes in a tree-like structure. It helps you visually understand how a process starts and its connection with other active processes. pstree The Glances Tool The Glances tool provides a brief overview of the currently running process. However, you have to install the tool by running the below command: Operating System Command Debian/Ubuntu sudo apt install glances Fedora sudo dnf install glances Arch Linux sudo pacman -Sy glances openSUSE sudo zypper install glances After the successful installation, you can open the Glances by running the following command: glances A Quick Summary Knowing how to list processes can help free up the space and turn off the currently running process. This article covered four ways– the top, ps, pstree, and pgrep commands. You can choose to use any of them according to what suits you best. We recommend you use any commands carefully, or you may get errors. View the full article

Whether you launch the file manager, run a system service, or execute a command in the terminal, each action initiates a process. These processes run in the foreground or background while consuming system resources such as memory, CPU, and disk space. Therefore, processes essential to ensure appropriate functioning of the system. Moreover, users sometimes need to terminate processes for reasons like an unresponsive application, a software update, security concerns, etc. So, this guide will briefly explain the methods you can use to kill a process in Linux using suitable examples. Linux has three commands– kill, pkill, and killall, to kill processes. Let’s divide this section further to discuss each of these commands one at a time. The kill Command If you want to terminate a process gracefully, do it using the kill command: kill PID Replace PID with the process ID you want to remove. This will send the kill signal to that process. For example, let’s eliminate PID 3906 using the kill command: kill 3906 Please remember that on successful execution, these commands(including those mentioned below) return nothing. The pkill Command You can use the pkill to eliminate a process using its name. If an application has multiple processes running, you can kill them all using the pkill command. pkill process_name Here, putting the application name in place of the term process_name will kill all the processes matching to it. To kill the processes initiated by the Firefox browser, you must enter the following command: pkill firefox The killall Command If a process has various sub-processes running, please run the pkill command to kill them all. pkill process_name Putting the application name in place of the term process_name will kill all the processes matching it. To kill the processes initiated by the Firefox browser, you must enter the following command: killall firefox A Quick Wrap-up Killing processes in Linux is fundamental, and it helps you maintain a healthy system. It assists you in troubleshooting unresponsive applications, resource optimization, etc. This guide outlines all the three commands you can use to kill processes. The kill command helps you while working with the process IDs, whereas the pkill and killall commands come in handy for process names. View the full article

Linux offers the capability to customize almost every single aspect of your system. One such feature is the ability to control the number of processes a user can have. This gives the system admins better control over the system and optimizes resource consumption. This article will show you how to set max user processes in Linux. Setting Max User Processes A single user has the capability to run a large number of processes. Linux is a multi-user operating system. Now, imagine multiple users running tons of processes. Even if each of the processes does not consume too many hardware resources on its own, the sum of all user processes may eventually hog the entire system. To avoid such a situation, system admins may limit the number of processes that each user can open. The limit can be imposed temporarily or permanently. Depending on your target scenario, follow the most appropriate method. Set Max User Processes Temporarily This method temporarily changes the limit of the target user. If the user restarts the session or the system is rebooted, the limit will reset to the default value. Ulimit is a built-in tool that is used for this task. Ulimit can impose limits on various resources for a particular user. The only downside (as mentioned earlier) is that it is temporary. Log in as the target user and check the current process limit. $ ulimit -u Next, define the limit to 12345. $ ulimit -u 12345 Verify the change. $ ulimit -u Set Max User Processes Permanently The following method is more reliable in a real-life scenario. If the user logs out or the system reboots, the change will not disappear. Here, we will still use the Ulimit tool. However, instead of directly making changes using the ulimit command, we will tweak the system configuration tool that Ulimit uses to assign the limits to the target users. Check out the limits.conf. command below: $ cat /etc/security/limits.conf To add an entry to the file, it should be in the following format: $ <domain> <type> <item> <value> The following list provides a definition for each field: domain: A domain can be a user, user group, GUID ranges, etc. type: The type of the limit. It can be either hard or soft. item: What resource will be limited. For this guide, we’ll be using “nproc”. value: The value of the limit. Next, we will discuss limit types. If you want the domain to have a maximum process limit hovering around a certain value, then you use the soft limit type. If you want the domain to have a maximum process limit at a fixed value, then you use the hard limit type. As for the item fields, there are a number of these. For the full list, I recommend checking out the limits.conf man page. $ man limits.conf Now, back to tweaking the limits.conf file. To edit the file, open it in your favorite text editor. Note that you must run the command with root privileges. Otherwise, the changes cannot be saved. $ sudo vim /etc/security/limits.conf The following line is just an example. It will set a hard limit of 12345 for the user viktor. $ viktor hard nproc 12345 Save the file and close the editor. To take the changes into effect, the user may need to restart the session or the system may have to reboot. Verify the result. $ ulimit -a viktor Conclusion Limiting max user processes is a common task that system admins may have to perform. Hopefully, this guide was helpful in that regard. If you are interested in learning more about how to impose limits on other resources, check out the article Linux ulimit command. Ulimit is the primary tool that imposes resource limits on users in Linux. Happy computing! View the full article