htop - Task manager for Linux

If your computer system’s per­for­mance is too slow or if it suddenly keeps freezing, you need to ask yourself: are un­de­tectable programs or processes running in the back­ground that are putting a strain on the system? And are they even­tu­al­ly causing these problems? The task manager (also known as 'process manager'), can answer this question. Since it collects in­for­ma­tion about all the active system processes, it presents them in a graph and dis­tin­guish­es the problem at hand. In addition to this mon­i­tor­ing function, task managers are also able to manage these processes: you can not only determine which programs and services are exerting a par­tic­u­lar strain on your system, but you can also terminate them.

Current operating systems have process managers installed by default. If the operating system does not, they provide cor­re­spond­ing commands to display and manage processes. There are also al­ter­na­tive programs like htop, which are known to represent processed data in a better way and are much easier to use. Orig­i­nal­ly developed ex­clu­sive­ly as a Linux task manager, the GNU-licensed tool fulfills the tasks of the command top, which is used to display active processes on Unix-like systems. Fur­ther­more, the terminal is replaced by a text interface based on the C library, ncurses. In this manner, htop can be operated easily using the keyboard and without having to enter cum­ber­some commands. The process manager, which was published by Hisham Muhammad in 2004 and has been con­stant­ly evolving ever since, doesn’t just show the active tasks, but also their in­di­vid­ual threads. These im­ple­men­ta­tions provide a more detailed de­scrip­tion of the process in question, meaning that they allow an even more accurate eval­u­a­tion. There are some keyboard shortcuts for htop; in a desktop en­vi­ron­ment, the process manager can even be operated by mouse. If you use the latest ncurses library, you can use the mouse to scroll through the process overview. In addition to Linux dis­tri­b­u­tions such as Ubuntu, the task manager is also available to use on the Unix de­riv­a­tives, FreeBSD, OpenBSD, and Mac OS X.

The main area lists all active processes using the following values:

The htop footer has different buttons that can be selected by mouse click. They can also be accessed using the function keys F1 to F10.

While other areas of the tool are only concerned with col­lect­ing processes and sta­tis­tics, the last-mentioned buttons on the footer are what are used to operate htop. It doesn’t matter whether you use the mouse or the keyboard. However, if you decide to use the keyboard, you will have a number of useful key commands that go beyond the pos­si­bil­i­ties of the function keys and make task manager work extremely easy. The ability of each function key and ad­di­tion­al shortcuts are sum­ma­rized here:

As is common for open source programs, you can install htop using either source files or binary files and the package manager of each dis­tri­b­u­tion. Download and install the former with the following commands:

If, on the other hand, you prefer the variant with the package manager, you should first ensure that the current htop version is included for your dis­tri­b­u­tion. If it is, then simply follow the usual in­stal­la­tion pattern for your system. For example, in Ubuntu, the task manager is set up by entering the following command:

htop is a good example of the classic Unix command top and scores plus points with its ncurses-based text interface. As a result, the in­di­vid­ual processes and threads are not only presented in an appealing manner, but operating with a mouse or keyboard is a lot more intuitive than with pure command line tools. The clever use of function keys and various ad­di­tion­al key commands sim­pli­fies nav­i­ga­tion and con­fig­u­ra­tion, no matter whether processes should be ter­mi­nat­ed, or pri­or­i­ties should be changed. Besides top (that is already installed by default), there are al­ter­na­tives for ex­pe­ri­enced ad­min­is­tra­tors. This includes the similar process manager atop as well as the cross-platform tool Glances.