Chapter 3.1.2 htop
==================

htop is an ncurses text interface task manager that can be controlled by the keyboard. htop also closes unresponsive programs by killing the process.

Usage
------
To view how much RAM is being used on your system is under :guilabel:`Mem` and then a [ number based on how many Gigabytes of memory. The :guilabel:`Swp` line lists how much swap is used. The numbers going down with a bar with a percentage next to them display CPU usage on each of your CPU cores.

To see how many process are running on your system see the :guilabel:`Tasks` row. :guilabel:`Load average` shows your system load over the past one five and fifteen minute is why there are three numbers see `Wikipedia load (computing) <https://en.wikipedia.org/wiki/Load_(computing)>`_ for more information. :guilabel:`Uptime` shows how long your computer has been booted.

After the bottom there is a green bar that says :guilabel:`PID` for the Process ID of a user, The user the process responds to, :guilabel:`RES` is how much RAM the process is currently using. :guilabel:`CPU%` shows how much as a percent of CPU time the process is using, mem% is a percent of the RAM your process is using. :guilabel:`Time` shows how long the process has been running. :guilabel:`Command` shows the command line command of the process. To view any cut off part of the :guilabel:`Command` field press the :kbd:`Right Arrow` to view the cut off area of the window. To move your window back to where it was press  the :kbd:`Left Arrow` key.   

To select the process below the currently selected one press :kbd:`Down Arrow` to select the process below. To select the process above the currently selected one press :kbd:`Up Arrow` to select the process above. To select the next group of processes on your screen press :kbd:`Page Down`. To select the previous group of process on your screen press :kbd:`Page up`. To choose the last process on your system press the :kbd:`End` key. To choose the first process press the :kbd:`Home` key.

.. image:: htop.png

You can press :kbd:`F1` or :kbd:`?`  to bring up a help dialog on htop. Pressing :kbd:`F3` or :kbd:`/` lets you search for a particular process. To reverse sort order press :kbd:`Shift +I`. Pressing :kbd:`F4` makes it so you can only see processes matching a certain pattern. To get out of the view of your search for a pattern press the :kbd:`Escape` key. Pressing :kbd:`F5` is what you press to view the processes in a tree. To get back to the default view press :kbd:`F5` again. Pressing :kbd:`F9` lets you kill a process with different signals to send to the process and 15 will terminate the process while 9 will Kill it. Lastly pressing :kbd:`F10` or :kbd:`q` will quit htop and return you to a terminal.

.. image:: htop-filter.png

To change how your process are sorted press :kbd:`F6` which will bring up your own menu to sort by by :guilabel:`PID`, :guilabel:`USER`, :guilabel:`Priority`, :guilabel:`NICE`, :guilabel:`M_Size`, :guilabel:`M_Resident`, :guilabel:`M_Share`, :guilabel:`State`, :guilabel:`Percent_CPU`, :guilabel:`Percent_Mem`, :guilabel:`Time`, or :guilabel:`Command`.  To select a menu item press :kbd:`Enter`.

:kbd:`F2` brings about a customizable settings on htop. The :guilabel:`Meters` brings up meters like CPU average. The :guilabel:`Display Options` has option for different ways to display in htop. The :guilabel:`Colors` tab brings up different color schemes for htop. To select a different color scheme press the :kbd:`Up arrow` or :kbd:`Down arrow` keys. To select a new color scheme press the :kbd:`Spacebar` key.  

.. image:: htop-setup.png

Version
-------
Lubuntu ships with version 2.2.0 of htop. 

How to launch
-------------
To launch htop from the menu :menuselection:`System Tools --> Htop` with the Icon that looks like the green H made out of text or run  

.. code:: 

   htop 

from the command line. 
