htop is an interactive process viewer for Unix systems. It is a text-mode application (for console or X terminals) and requires ncurses.

htop is NOT installed by default

We can run htop from a command window by entering:

  htop

htop is a more graphical version of the Linux top command (which is available on all distros). htop is much better as displaying the resources of multi-processor systems.

The htop display is split in to two main areas. At the top of the page is the details about the processors and memory, in this example we can see 48 processors (they are hyper threading so its actually 24 cores from two processers (so 2 x 12 core CPUs).

Each core can show up to 100% utilisation, so a server running at full CPU load would show a total CPU usage of 4800%

The bottom window shows each process running (PID is process ID) and what resources each process is consuming.

htop Shortcuts

  Description                Function Keys        Shortcut Keys
  Help                       F1                   h
  Setup                      F2                   s
  Search Process             F3                   /
  Invert Sort Order          F4                   |
  Tree                       F5                   t
  Sort By                    F6                   >
  Nice - (change priority)   F7                   [
  Nice + (change priority)   F8                   ]
  Kill a process             F9                   k
  Quit                       F10                  q