Top (software)

Top is a command in most Unix -like operating systems that prints a constantly updated list of running processes in the system. This top also displays the CPU utilization, memory usage, as well as many other information. Some versions of top can be configured in terms of the information to be displayed is very flexible.

The command is very useful among other things for system administrators, because it gives an overview of the user and the system processes the most strain. For further processing by a script language or to record the output of top can also redirect to a text file.

Compared with the command for single listing processes, ps, offers a constant update of the top advantage that the command does not need to be constantly restarted in order to stay up to date. In addition, top displays only as many processes as will fit in the terminal window. This will display only the most stressful processes ( default ).

Development and variants

The development was inspired by the top of the monitor process / topcpu commands of the operating system VMS. William LeFebvre wrote the first implementation of top in April 1984 for BSD 4.1 as a student at Rice University. The project was released as open source under the very liberal BSD license, which is why the program quickly spread in various BSD systems and other Unix systems.

Top has been repeatedly re-designed from the ground up for various operating systems and under different licenses. AIX Version 4.3 contained an extended version called topaz. The first version of Linux was designed by Roger Binns, the newest and most widely used variant of James C. Warner supports both a colored representation of the process list and other enhancements.