# &app; Manual V&manrevision;

## Introduction

System Monitor lists system processes and monitors system usage. System Monitor shows which processes are running and how those processes are related to each other in a table that the user can read and search. It also provides detailed information about individual processes and allows the user to control which processes are running. System Monitor also displays how much processor (CPU) capacity the system is using, how much memory and swap space the system is using, and how much disk space the system is taking up on each device. System Monitor displays this information in a graphical display so that users can see what the system is doing. Users can then modify the behavior of the system through the same graphical display.

To run System Monitor, select SYSTEM TOOLS System Monitor from the Applications menu, or type `gnome-system-monitor` on the command line.

System Monitor is included in the `gnome-system-monitor` package, which is part of the GNOME desktop environment. This document describes version &appversion; of System Monitor.

## Using System Monitor

System Monitor has the following uses:

Process Listing

- - Monitors processes that are running; and

  - Modifies processes that are running.

System Monitor

- - Monitors demands on the processor (CPU);

  - How much memory is consumed; and

  - How much space is available on each device.

This section describes the basic usage of System Monitor.

### Process Listing

Starting System Monitor opens the Process Listing window, shown in processlisting-fig. The window shows the names of the processes that are running under the Process Name column on the left side of the window. In some cases processes are shown in outline form. Child processes are listed below their parents and indented. Clicking the mouse on the triangle next to a process name expands the listing to show the child processes beneath it. Clicking on the triangle again collapses the list of child processes.

#### Process Listing window

Process Listing window

This window lists the processes that are running and shows how the processes are related to each other.

Process Listing shows the application icons associated with each process in the far left column. The default table shows a column for the process name and six columns that provide additional information. The Arguments column shows the command with the arguments that were used to start the process. The User column shows which user owns the process. The Memory column shows how much total system memory that process is using. The VM Size column shows how much virtual memory (disk space) the process is using. The %CPU column shows how great a percentage of the processor's capacity the process is using. The ID column indicates the process identifier (pid), a number that uniquely identifies the process and can be used to manipulate the process on the command line.

By default, the processes are sorted by process in alphabetical order. Clicking on the header above a column reorders the table by sorting the information in the column in alphabetical (a-z) or numerical order. Clicking again on the column sorts the data in reverse alphabetical (z-a) or reverse numerical order.

#### The Search Text Box

The search text box allows the user to search for a process by name. Wildcards are not supported. Once the process is found, it is highlighted, and the user can perform operations on it using either contextual menus or the menu bar.

#### The View Button

Clicking on the View button reveals a menu with three options: View All Processes, View My Processes, and View Running Processes. Clicking on View All Processes shows all processes on the system for all users. View My Processes shows only those processes that belong to the current user. View Running Processes shows only the processes that are running at that moment.

#### Processes and Contextual Menus

Right-click on one of the processes listed in the Process Listing window and a contextual menu will appear with the following choices:

- Change Priority —This menu choice brings up a dialog box with a slider that allows the user to change the priority of a process. Sliding the bar to the right gives the process a higher "Nice value" and a lower priority. A process with a lower priority will run after processes with a higher priority, and giving a process a lower priority (higher Nice value) can keep it from interfering with higher priority processes. Sliding the bar to the left gives the process a lower Nice value and a higher priority. Giving a process a higher priority (lower Nice value) helps ensure that it will run before processes of a lower priority. Generally, child processes inherit their priority from parent processes, but Change Priority allows the user to set priorities manually. In order to set the Nice value lower than zero (and give the process a higher priority) the user needs to enter the root password, unless the user is already logged in as root.

- Memory Maps — This menu choice brings up a dialog box containing the table shown in memorymaps-fig which displays memory maps of of the highlighted process. The name of the process appears at the top of the table.

  ##### Memory Maps

  Memory Maps

  This table shows the memory maps for a process.

  The table contains the following columns:

  - Filename: This column shows the full path name of the file listed.

  - VM Start

  - VM End

  - Flags

  - VM Offset

  - Device

  - Inode

  Left clicking on the column header will reverse the order in which information is displayed from top to bottom.

- Hide Process — This menu choice hides the process so that it is no longer displayed under Process Listing. (Child processes are still displayed in the main process branch.) To display a process that has been hidden, click on the Menu Bar on the Edit menu and then click on Hidden Processes or type Ctrl P. This will display a dialogue box with a list of the processes that have been hidden. To display the hidden process in the Process Listing table, highlight the hidden process with the mouse and click on the button Remove From List or type Alt R. Left click on the Close button or type Alt C to close the window.

  ##### Hidden Processes

  Hidden Processes

  This dialog box allows the user to see which processes in the Process Listing window are hidden. Clicking the Remove From List button displays the process.

- End Process — This menu choice ends the process. This is the preferred method of stopping a process.

- Kill Process — This menu choice kills the process. Normally Kill Process is necessary only if End Process does not work.

#### Other Buttons

The More Info button is located in the lower left corner of the Process Listing window.

More Information

- Clicking on the More Info button or typing Alt I reveals more information about whichever process is highlighted in the Process Listing window as shown in moreinfo-fig.

Less Information

- The user can click the Less Info button (in the same place as More Info) or type Alt I to toggle the information display and show less information.

##### More Info

More Info

Highlight a process in the Process Listing window and click on the "More Info" button in the lower left corner of the window to show the information about a process displayed in the figure above.

More Info shows the following information:

- The command used to start the highlighted process;

- Whether the Status of the process is sleeping or running;

- The Priority of the process (with the Nice number used to set the Priority in parentheses);

- The total memory used by the process;

- The RSS (or physical) memory used by the process; and

- The amount of memory that is Shared.

To hide this information, click on the Less Info button in the lower left corner. The user can also toggle More Info/Less Info with the Alt I key combination.

The End Process button ends the process highlighted in the Process Listing window. Clicking on the End Process button or typing Alt P will display an optional dialogue box that gives the user a choice between canceling the action Alt C or ending the process Alt E.

### Menu Bar

Most of the menu choices in the menu bar apply to the Process Listing window. If the System Monitor window is on top, menu choices that apply only to the Process Listing will be greyed out. The menu bar contains the following choices:

File

- This menu contains:

  - Ctrl Q Quit — This exits the program.

Edit

- This menu contains:

  - Ctrl R Change Priority — Highlight a process in the Process Listing table and select this menu choice to change the Priority or "Nice value" of a process. You must be a superuser to do this.

  - Ctrl H Hide Process — Highlight a process in the Process Listing table and select this menu choice to hide a process. Select Edit: Hidden Processes to show hidden processes.

  - Ctrl E End Process — Highlight a process in the Process Listing table and select this menu choice to end the process. You must be the owner of the process or the superuser to do this.

  - Ctrl K Kill Process — Highlight a process in the Process Listing table and select this menu choice to kill the process. You must be the owner of the process or the superuser to do this. If possible, it is normally preferable to end a process rather than kill it.

  - Ctrl P Hidden Processes — This menu choice will list any processes that are not displayed in the Process Listing window because they are hidden as shown in hiddenprocess-fig. If no processes are hidden, it will display an error message.

  - Preferences — This shows the preferences dialog for Process Listing, Process Fields and System Monitor.

    Process Listing

  - The Process Listing tab allows the user to control the following features:

    Update Interval

  - Set the interval in seconds at which the Process Listing will update.

- Display Process Dependencies and Threads.

- Display warning messages before ending, killing or hiding processes in the Process Listing window.

Left click the Close button or hit Alt C to exit preferences.

Process Fields

- The Process Fields tab allows the user to select which columns to display in the Process Listing window. The user can select the following columns to display in the Process Listing window:

  - Process Name: This column show the name of the process.

  - Arguments: This column shows the arguments used when the process was started.

  - Status: This column shows whether a process is running or sleeping.

  - Memory: This column shows the amount of memory that the process uses.

  - VM Size: This column shows the amount of virtual memory allocated to a process.

  - Resident Memory: This column shows the amount of physical memory allocated to a process.

  - Shared Memory: This column shows the amount of shared memory allocated to a process. Shared memory is memory that can be accessed by another process.

  - RSS Memory: This column shows the total amount of physical memory used, not counting pages swapped out.

  - %CPU: This column shows the percentage of Central Processing Unit (CPU) time the process uses.

  - Nice: A higher nice value indicates that a process has a lower priority, and will wait for higher priority processes. A lower nice value indicates that a process has a higher priority and will execute before lower priority processes.

  - ID: This column shows the unique Process Identification number (PID) for the process.

System Monitor

- - Left click System Monitor tab to see the System Monitor preferences. Under Graphs, the user can set the interval at which the graphs update in seconds. Left clicking on the boxes to the right of Background Color or Grid Color brings up a color change dialog. The user can then adjust the color of the background or the grid lines in the % CPU Usage History and % Memory/Swap Usage History graphs, which are described in system-monitor.

View

- This menu contains:

  - Ctrl M Memory Maps — This displays the Memory Maps table shown in memorymaps-fig.

### System Monitor

The second window in System Monitor is the System Monitor shown in system-monitor-fig. To see the System Monitor, click on the System Monitor tab to the right of the Process Listing tab.

#### System Monitor

More Info

This System Monitor window shows information about CPU usage, Memory/Swap history usage, and disk space.

As shown in system-monitor-fig above, the System Monitor has three panels:

% CPU Usage History — This panel shows a graph of the percentage of processor (CPU) capacity used over time.

% Memory/Swap Use — This panel shows a graph of the percentage of memory and swap space used over time. Users can change the colors of the lines used in the graphs by clicking on the colored buttons in the lower left corner of the %CPU Usage History or % Memory/Swap Use graphs.

At the bottom of the System Monitor panel is a Devices table showing the amount of used disk space and total disk space by device name and directory as shown in system-monitor-fig above. Left clicking and dragging the space between the graphs and the Devices table allows the user to change the size of the Devices table.

## About &app;

&app; was written by Kevin Vandersloot (kfv101@psu.edu). Erik Johnsson (zaphod@linux.nu) provided icon support.

To report a bug or make a suggestion regarding this application or this manual, follow the directions in this document.

This program is distributed under the terms of the GNU General Public license as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. A copy of this license can be found at this link, or in the file COPYING included with the source code of this program.