icewm - lightweight X11 window manager
icewm is a lightweight window manager for the X11 window system. It aims to be small, fast and familiar to new users. icewm is called a re-parenting window manager, because it draws small frames around application windows. Windows are manipulated via the mouse by dragging or resizing this frame. It is also called a stacking window manager, because windows can overlap. Many windows may exist, some hidden behind others, while interaction takes place with the currently visible ones. icewm supports a configurable number of virtual desktops. It provides a task bar for monitoring applications and a pager to switch between desktops. icewm is largely compliant with the ICCCM 2.0, WinWM/WMH and NetWM/EWMH window manager specifications.
icewm was originally designed to emulate the look of Motif, OS/2 Warp 4, OS/2 Warp 3 and Windows 95. Since it has a theme engine other styles are possible. The installation comes with several configured themes. A menu allows to choose between themes.
Generally, it tries to make all functions available by both keyboard and mouse. Configuration is very good through various preferences files. However, configuring is not required: it works fine out of the box.
The icewm package includes several programs:
The actual window manager. It positions application windows on screen and decorates them with borders. It gives input focus to the current active application. icewm supports different focus modes, which are explained below. It draws a small task bar at the bottom of the screen, which gives easy access to programs, to virtual desktops, to active applications, and to a small set of monitoring applets.
The background setting application. It can assign plain background color or images in different formats to the X background. Each work space can have its own background. It supports semi-transparency. Semitransparent background image and colour can be configured. When the background image has changed then icewmbg(1) can be notified to update the background. Multi-head monitor setups are fully supported. This program should be started before icewm. See the icewmbg(1) man page for details.
icewm-session(1) is the preferred program to start the IceWM system.
It first loads additional environment variables from the optional
env file. Then it starts icewmbg(1) and icewm. It also runs
startup script and implements basic session management.
On termination the
shutdown script will be run first, then
icewm-session(1) will terminate icewm and icewmbg(1).
icewm-session(1) will also start the optional icesound(1)
if you give it the –sound option. See icewm-session(1).
A powerful tool to control window properties and to interact with the window manager. It is typically used in shell scripts. See icesh(1).
A small document browser, which is used by icewm to display the ‘IceWM manual’ and some man pages.
A utility for passing IceWM-specific window options to icewm. The options are used to configure the first application which is started subsequently. See icewmhint(1).
Plays audio files on GUI events which are raised by icewm. It supports ALSA, AO and OSS. See the icesound(1) man page.
Generate an icewm menu with executable desktop applications according to XDG specifications. See the icewm-menu-fdo(1) man page.
Configures GNOME to start IceWM instead of its own WM.
Each of the IceWM executables supports the following options:
Use FILE as the source of configuration options. By default icewm
looks for a file named
preferences. Typically this file is stored as
or in one of the configuration directories explained below. It contains
a long list of options which allow the user to tweak the behaviour of
icewm to ones taste. A default
preferences file contains comments
about the purpose of each option, the range of useful values and the
current or default value. A
preferences file is a readable text file
which can be modified with the help of a text editor. If this option is
given to icewm-session(1) then it is passed on to icewm. If
icewm is started independently then this option can be given to
icewm directly. However, usually one will want to use a
preferences file from a default location.
Use NAME as the name of the icewm theme to use. A theme defines
the look and feel of icewm, like colours, fonts, buttons and button
behaviour. Originally a theme defined options to emulate the appearance
of other desktop environments, like Motif, OS/2 Warp, or Windows. Over
the years many new original themes have been designed with beautiful
icons and backgrounds, which advance the state of the art in desktop
look and feel. Many of them can be downloaded from the website
https://www.box-look.org/ and stored in one of the directories
$XDG_CONFIG_HOME/icewm/themes/ or in
$HOME/.icewm/themes/. You can then activate such a theme via the
menu in the lower left corner of the display. A default theme is
specified in one of
$XDG_CONFIG_HOME/icewm/theme, or in
$HOME/.icewm/theme. When a
new theme is selected then this value is overwritten, so that the next
time icewm is started this choice is reused.
DISPLAY specifies the connection to the X11 server. If this option
is missing, as is usually the case, then DISPLAY is read from the
This option is sometimes used in software development of icewm. It specifies to use a slower synchronous communication mode with the X11 server. This is irrelevant for normal use of icewm.
Gives a complete list of all the available command line options with some very brief explanation.
Shows the software release version for this program.
The icewm program supports some additional options:
Use a 32-bit visual for translucency. This can also be set in
the preferences file as
Instructs icewm to replace an existing window manager. Provided that the window manager being replaced is ICCCM 2.0 compliant, once it notices that it is to be replaced it will cease operations and typically stop execution. This allows icewm to establish itself as the only active window manager.
Tell icewm to restart itself. This reloads the configuration from file.
Briefly show IMAGE on startup in the center of the screen.
This can also be set in the preferences file as Splash=
Shows a list of configuration options which were enabled when icewm was compiled from source code. This can be helpful if one suspects some functionality may be missing.
Gives a list of directories where icewm will look for configuration data. This list is printed in the actual order in which icewm uses it to search for configuration files.
icewm will search all the configuration directories for theme files and print a list of all found themes.
This gives a long list of all the internal icewm options with their actual values after icewm has processed all of the configuration and theme files. In some advanced scenarios this can be helpful to inspect which configuration was chosen or whether option formatting was correct.
Give a list of the current X extensions, their versions and status.
Enable tracing of the paths which are used to load configuration and/or icons.
On startup icewm launches the task bar at the bottom of the screen. The task bar consists from left to right of the following components:
The Menu button in the lower left corner gives access to the icewm root menu. This menu has sub-menus to start applications, to control icewm settings, and the icewm Logout menu.
The Show Desktop button unmaps all application windows to fully uncover the desktop.
The Window List Menu button gives access to a menu with a list of active windows for the current work space and a list of work spaces with sub-menus for their active application windows.
The Toolbar is a list of icons for applications which are defined in the toolbar configuration file.
The Workspace List shows one button for each work space. The current
work space is indicated by a pressed button. Pressing another work space
button switches to that work space. The work spaces are defined in the
preferences file. When
PagerShowPreview is turned on a small
graphical summary for each workspace is shown.
The Task Pane consists of a list of wide buttons for each application
which is running on the current work space. Each task button shows the
application icon and the application title. The active application is
indicated by a pressed button. This is the application which has input
focus. Pressing another button activates that application: it is
brought to the foreground and receives input focus. Other mouse
controlled activities on the window buttons are dragging window buttons to
(temporarily) rearrange the order (with left mouse button) or closing
the application window (with middle button while pressing and holding
If there are not many application buttons then a stretch of plain task bar is visible. Clicking on it with the right mouse button gives the task bar menu. Even with a full task pane, this menu can be usually accessed by right-clicking the bottom right corner of the taskbar.
The Tray Applet shows system tray objects.
The APM Applet shows battery power status.
The Net Applet shows network activity. Network devices to monitor
are given by the
The Memory Applet monitors memory usage.
The CPU Applet monitors processor utilization.
The Mailbox Applet monitors mailbox status changes. The location of
the mailbox is given by the
MailBoxPath preferences option or else by
The Clock Applet shows the current time and date. It is configured
The Task Bar Collapse button collapses the task bar and hides it.
Not all icewm applets may show up on the task bar. They must have
been enabled during configuration of the icewm software. Their
appearance is also controlled by options in the
Of all visible windows only one can be the active window. This is the window which has input focus. It is the primary receiver of keyboard and mouse events and hence one can interact with the application which created that window. A primary task of a window manager is to allow the user to switch input focus between different windows. The primary means to do this is the mouse pointer. By moving the mouse pointer over the screen to another window, and perhaps also by clicking on a window, input focus can be directed.
FocusMode option controls the way icewm gives input focus to
applications. It is initialized by the
file. The focus mode is set via the Focus menu. icewm supports
six focus models:
The default focus mode. In this mode changing input focus requires to click a window with the left mouse button. The window is raised if needed. When an application requests focus its task pane button flashes. This gives the option to honor this request or to ignore it. When a new application window appears it automatically receives focus. Also when a hidden application raises to the front it receives focus.
Sets input focus merely by moving the mouse pointer over a window. It is called sloppy, because if the mouse then leaves the window and moves to the desktop background the input focus remains with the last active window. When a window receives focus it is raised. When an application requests focus its task pane button flashes. A new application or an application which raises to the front automatically receives focus.
Focus is even more user-controlled than Click-to-focus. When a window receives focus it is not raised by default, unless the frame border is clicked. No flashing occurs when an application requests focus. When a new application window appears it does not receive focus. Only by explicit clicking on a window is focus directed.
Like Sloppy but focus remains with the last window. New applications don’t receive focus and are mapped behind other windows. When an application raises to the front it still does not get focus.
Like Sloppy but no disturbing flashing occurs on the task bar when an application requests focus.
A focus mode which is defined in detail by ten options in the
All non-Custom focus modes override these ten options.
Apart from the mouse, icewm supports changing input focus in two
other ways. Both involve the keyboard. The first uses the
QuickSwitch window. It is activated by pressing
Alt+Shift+Tab. A window pops up in the centre of the screen with a
narrow band over the next or previous window which will receive input
focus when the
Alt key is released. By repeatedly pressing
Alt+Shift+Tab one can cycle through all windows.
The second keyboard method involves pressing
Alt+Shift+Esc. Input focus is immediately changed to the next or
previous window, which will be raised to make it fully visible.
And finally, there is another way which is a hybrid of keyboard and
mouse control. It involves the
QuickSwitch popup explained before,
Alt+Tab and while still holding
Alt a left click
on one of the list items causes the activation of the related window.
A second important task of a window manager is to place new windows on
the screen. By default icewm chooses a placement with minimal
overlap, but this is determined by the
SmartPlacement option in the
preferences file. If
SmartPlacement is turned off then windows
are placed in sequence from left to right and top to bottom. One can
also turn on
ManualPlacement. Then new windows appear initially in
the top left corner and the mouse cursor changes into a fist. By moving
the fist cursor to a suitable location and clicking the new window will
appear at the mouse click location.
Windows can overlap. Which window appears on top is determined by three features. Newer windows appear over older windows. By clicking on a window it is raised to the top. But both are overruled by the window layer. Windows can be placed in different layers via the Layers menu. Click with the right mouse button on the window frame and select Layer. From there choose one of seven window layers. These are ordered from higher to lower. Windows in higher layers appear over windows in lower layers.
icewm supports multiple virtual desktops called work spaces. A work
space is like a screen where a subset of all application windows are
mapped. Thanks to multiple work spaces we can more easily manage a
large number of applications. The number of work spaces and their names
are configurable in the
preferences file through the
WorkspaceNames option. By default four workspaces are created
with the names 1, 2, 3 and 4 thus:
WorkspaceNames=" 1 ", " 2 ", " 3 ", " 4 "
This syntax is typical for icewm options which receive multiple values. It is a list of comma separated values each of which can be quoted.
The work spaces are visible on the toolbar. One can switch to a
different work space by pressing the work space button in the toolbar,
but after becoming familiar with the ‘keyboard shortcuts’ below one will
want to use a hotkey to choose a work space. If the
options is enabled in the
preferences file (with sub-options
VerticalEdgeSwitch) then one can move to
the next or previous workspace by moving the mouse to the edge of the
ContinuousEdgeSwitch option enables continuous movement
to subsequent workspaces. The
EdgeSwitchDelay option says how long
to wait before a change of workspace occurs.
To move an application window to a different work space one can use a keyboard shortcut. Another option is to select the Move To submenu in the window menu of the window frame.
If EnableAddressBar=1 then KeySysAddressBar=
activates the address bar in the task bar.
If ShowAddressBar=1 it is always shown. This is a command line in
the task bar where a shell command can be typed.
Enter will execute the command.
/bin/sh will be used to execute the command.
Control+Enter the command is executed in a terminal
as given by TerminalCommand.
The address bar maintains a history which is navigable by the Up
and Down keys.
It supports file completion using
A rich set of editing operations is supported,
icewm supports a large number of hotkeys to activate some behaviour
with a single key combination. These are all configurable in the
preferences file. Here we give their default values, followed by
their preferences names and short descriptions of their effect:
KeyWinRaise raises the window which currently has input focus.
KeyWinOccupyAll makes the active window occupy all work spaces.
KeyWinLower lowers the window which currently has input focus.
KeyWinClose closes the active window.
KeyWinRestore restores the active window to its visible state.
KeyWinNext switches focus to the next window.
KeyWinPrev switches focus to the previous window.
KeyWinMove starts movement of the active window.
KeyWinSize starts resizing of the active window.
KeyWinMinimize iconifies the active window.
KeyWinMaximize maximizes the active window with borders.
KeyWinMaximizeVert maximizes the active window vertically.
KeyWinMaximizeHoriz maximizes the active window horizontally.
KeyWinFullscreen maximizes the active window without borders.
KeyWinRollup rolls up the active window.
KeyWinHide hides the active window.
KeyWinMenu posts the window menu.
KeyWinArrangeNW moves the active window to the top left corner of the screen.
KeyWinArrangeN moves the active window to the top middle of the screen.
KeyWinArrangeNE moves the active window to the top right of the screen.
KeyWinArrangeE moves the active window to the middle right of the screen.
KeyWinArrangeSE moves the active window to the bottom right of the screen.
KeyWinArrangeS moves the active window to the bottom middle of the screen.
KeyWinArrangeSW moves the active window to the bottom left of the screen.
KeyWinArrangeW moves the active window to the middle left of the screen.
KeyWinArrangeC moves the active window to the center of the screen.
KeySysWinMenu posts the system window menu.
KeySysWinNext give focus to the next window and raise it.
KeySysWinPrev give focus to the previous window and raise it.
KeySysDialog opens the IceWM system dialog in the center of the screen.
KeySysMenu activates the IceWM root menu in the lower left corner.
KeySysWindowList opens the IceWM system window list in the center of the screen.
KeySysAddressBar opens the address bar in the task bar where a command can be typed.
KeySysWorkspacePrev goes one workspace to the left.
KeySysWorkspaceNext goes one workspace to the right.
KeySysWorkspaceLast goes to the previous workspace.
KeySysWorkspacePrevTakeWin takes the active window one workspace to the left.
KeySysWorkspaceNextTakeWin takes the active window one workspace to the right.
KeySysWorkspaceLastTakeWin takes the active window to the previous workspace.
KeySysWorkspace1 goes to workspace 1.
KeySysWorkspace2 goes to workspace 2.
KeySysWorkspace3 goes to workspace 3.
KeySysWorkspace4 goes to workspace 4.
KeySysWorkspace5 goes to workspace 5.
KeySysWorkspace6 goes to workspace 6.
KeySysWorkspace7 goes to workspace 7.
KeySysWorkspace8 goes to workspace 8.
KeySysWorkspace9 goes to workspace 9.
KeySysWorkspace10 goes to workspace 10.
KeySysWorkspace11 goes to workspace 11.
KeySysWorkspace12 goes to workspace 12.
KeySysWorkspace1TakeWin takes the active window to workspace 1.
KeySysWorkspace2TakeWin takes the active window to workspace 2.
KeySysWorkspace3TakeWin takes the active window to workspace 3.
KeySysWorkspace4TakeWin takes the active window to workspace 4.
KeySysWorkspace5TakeWin takes the active window to workspace 5.
KeySysWorkspace6TakeWin takes the active window to workspace 6.
KeySysWorkspace7TakeWin takes the active window to workspace 7.
KeySysWorkspace8TakeWin takes the active window to workspace 8.
KeySysWorkspace9TakeWin takes the active window to workspace 9.
KeySysWorkspace10TakeWin takes the active window to workspace 10.
KeySysWorkspace11TakeWin takes the active window to workspace 11.
KeySysWorkspace12TakeWin takes the active window to workspace 12.
KeySysTileVertical tiles all windows from left to right maximized vertically.
KeySysTileHorizontal tiles all windows from top to bottom maximized horizontally.
KeySysCascade makes a horizontal cascade of all windows which are maximized vertically.
KeySysArrange rearranges the windows.
KeySysUndoArrange undoes arrangement.
KeySysArrangeIcons rearranges icons.
KeySysMinimizeAll minimizes all windows.
KeySysHideAll hides all windows.
KeySysShowDesktop unmaps all windows to show the desktop.
KeySysCollapseTaskBar hides the task bar.
KeyTaskBarSwitchNext switches to the next window in the task bar.
KeyTaskBarSwitchPrev switches to the previous window in the task bar.
KeyTaskBarMoveNext moves the task bar button of the current window
KeyTaskBarMovePrev moves the task bar button of the current window
KeySysWinListMenu shows the window list menu.
KeySysSwitchNext opens the
QuickSwitch popup (see “INPUT FOCUS”)
and/or moves the selector in the
KeySysSwitchLast works like
KeySysSwitchNext but moving in the
KeySysSwitchClass is like
KeySysSwitchNext but only for windows
with the same WM_CLASS property as the currently focused window.
You can control windows by a modified mouse button press:
MouseWinMove moves the window under the mouse over the screen.
MouseWinSize resizes the window. Keep the key and button pressed.
To enlarge the window move the mouse button away from the center. To
shrink it move towards the centre.
MouseWinRaise raises the window under the mouse.
MouseWinLower lowers the window under the mouse.
If this is equal to
MouseWinRaise and the window can be raised
MouseWinRaise takes preference over
Clicking on the desktop activates a menu. The middle button shows the
window list (
DesktopWinListButton=2). The right button shows the
root menu (
The title frame of a window also listens for mouse clicks. Left double
clicking maximizes the window (
double clicking rolls up the window (
Pressing a mouse button and moving it will move the window.
button lowers the window.
When the mouse is on the window frame then a left click raises the window. Dragging with the left button down resizes the window. Clicking the right button pops up the context menu. Dragging with the right button moves the window.
icewm supports the following signals:
icewm will restart itself. It is a way to reload the configuration.
icewm will cease to manage application windows and terminate.
icewm will initiate the logout procedure. If a
preferences option was configured it will be executed.
The directory for user private configuration files. When this
environment variable is not specified, the default directory is
$XDG_CONFIG_HOME/icewm when that directory exists, otherwise the
default value is
Gives the location of your mailbox. If the schema is omitted the local
“file” schema is assumed. This is used by the mailbox applet in the
task bar to show the status of your mailbox. If the
option in the
preferences file is set, then that one takes
icewm looks for configuration files in the following directories, in the given order, until it finds one:
Contains user-specific configurations. When ICEWM_PRIVCFG is
specified, this directory takes precedence over
Contains user-specific configurations. When this directory exists it
take precedence over
Contains user-specific configurations. This is the historical default directory.
Contains system-wide customized defaults. Please note that your local
installation may have been configured to use a different system
location. The output of
icewm --directories will show this location.
Default local installation settings.
icewm-session(1) loads additional environment variables from the file
env. Each line is subjected to POSIX shell expansion by
wordexp(3). Comment lines starting by a hash-sign (
#) are ignored.
icewm-session(1) will load those expanded lines which contain a name,
followed by an equals sign, followed by the value (which may be empty).
Defines the initial value for
FocusMode. Its default value is
FocusMode=1 (Click-to-focus). This can be changed via the menu.
icewm will save the Focus menu choice in this file.
Global keybindings to launch applications, which need not be window
manager related. Each non-empty line starts with the word
After one or more spaces follows a double-quoted string of the bound X11
key combination like
Alt+Ctrl+Shift+X. Then after at least one space
follows a shell command line which will be executed by icewm whenever
this key combination is pressed. For example, the following line
creates a hotkey to reload the icewm configuration:
key "Ctrl+Shift+r" icesh restart
A menu of applications; usually customized by the user. icewm provides the icewm-menu-fdo(1) program to generate a default menu. Similar programs are xdg_menu(1), mmaker(1) (MenuMaker), xde-menu(1), xdgmenumaker(1).
Contains general settings like paths, colors and fonts, but also options
to control the icewm focus behaviour and the applets which are
started in the task bar. The icewm installation will provide a
preferences file, which can be copied to the icewm user
configuration directory and modified.
Settings which override the settings from a theme. Some of the icewm
configuration options from the preferences file which control the
look-and-feel may be overridden by the theme, if the theme designer
thinks this is desirable. However, this
prefoverride file will again
override this for a few specific options of your choosing. It is safe
to leave this file empty initially.
An automatically generated menu of applications. This could be used by wmconfig(1), menu or similar programs to give easy access to all the desktop applications which are installed on the system.
This file contains the name of the default theme. On startup icewm
reads this file to obtain the theme name, unless icewm was started
with the –theme option. Whenever a different theme is selected from
the icewm Menu then the theme file is overwritten with the name of
the selected theme. This theme file contains the keyword
followed by an equals sign, followed by a double-quoted string with the
theme name. The theme name is the name of the theme directory, followed
by a slash, followed by the theme file. Usually the theme file is just
default.theme, but a theme may have alternatives. Alternatives are
small tweaks of a theme. These are specified in their own
file, which replaces
default.theme. If no theme file exists then
icewm will use the default setting of
Contains names of quick to launch applications with icons for the task
bar. Each non-empty non-comment line starts with the keyword prog.
After one or more spaces follows a name, which is displayed in a tool
tip whenever the mouse cursor hovers over the toolbar icon. This name
may be a double quoted string. Then follows the bare name of the icon
to use without extensions. This icon will be shown in the toolbar. The
last component is a shell command line which will be executed whenever
the user presses the icon in the toolbar. For example, the following
line in toolbar will create a button with tool tip
firefox icon which launches firefox(1) when clicked:
prog "Mozilla Firefox" firefox /usr/bin/firefox --private-window
Contains settings to control window appearance and behaviour which are specific to applications or groups of applications. Options can control the border, whether it appears on the task bar, the window list, the system tray and the work spaces. Also its layer, geometry, whether it can be moved, resized and closed.
Contains commands to be executed on icewm startup. This is an executable script with commands to tweak X11 settings and launch some applications which need to be active whenever icewm is started. It is run by icewm-session(1) when icewm starts.
Contains commands to be executed on icewm shutdown. This is an
executable script with commands to be executed in the last stage of
icewm termination. Typically they may undo some of the effects of
startup script. It is run by icewm-session(1) when icewm
Contains icons which are used to identify applications. Usually these
files are in the XPM format, but the PNG and SVG image formats are also
supported. The names of icon files may follow a specific naming
app_32x32.xpm. They start with a base name, usually
this is just a single word. Then follows an underscore, followed by a
size specification in the format
SIZExSIZE. This is followed by a
dot and the file extension, where the extension denotes the icon image
format. Common sizes are 16, 32 and 48 for small, large and huge icons.
This depends on the respective
IconSize preferences options.
Pictures of digits for the LED clock which is displayed in the
bottom-right corner of the task bar. These can be seen when the
TaskBarClockLeds options are both set to 1.
Icons which are used to display different states of the mailbox applet
in the task bar. There are five states and each has its own icon:
Audio files which are played by icesound(1) on GUI events. These
Pictures to customize the look of the task bar. These include:
A directory to store themes. Each theme is stored in its own
sub-directory in the
themes directory. A theme contains at least a
default.theme file, and optionally theme alternatives which are
additional files which have a
.theme file name extension and which
contain tweaks of the
How to create a theme is explained in the
IceWM Theme Creation Howto.
IceWM supports window opacity and transparency in connection with an
external compositor like compton(1). If a client window sets the
_NET_WM_WINDOW_OPACITY property on its window then icewm will copy
this to the outer frame window where compton will read it to adjust
the opacity of the client window. The opacity can also be controlled by
icewm when this is configured in the icewm-winoptions(5) file.
Another way is to use icewmhint(1) to preset the opacity level
immediately before starting the application. The opacity level of
running applications can always be queried or modified by icesh(1).
The _NET_WM_WINDOW_TYPE properties which icewm sets on its windows
are DIALOG, NOTIFICATION, POPUP_MENU and TOOLTIP. The output
icesh windows shows their WM_CLASS values. These can be helpful
to configure compton.
Examples of the above configuration files can be found in the default
installation path or in the system-wide defaults. See the output of
icewm --directories for their locations.
ICCCM 2.0: partial. NetWM/EWMH: extensive.
See the file
COMPLIANCE in the distribution for full details.
icehelp(1), icesh(1), icesound(1), icewm-env(5), icewm-focus_mode(5), icewm-keys(5), icewm-menu(5), icewm-menu-fdo(1), icewm-menu-xrandr(1), icewm-preferences(5), icewm-prefoverride(5), icewm-programs(5), icewm-session(1), icewm-set-gnomewm(1), icewm-shutdown(5), icewm-startup(5), icewm-theme(5), icewm-toolbar(5), icewm-winoptions(5), icewmbg(1), icewmhint(1), Xorg(1), Xserver(1), xinit(1), xprop(1), xwininfo(1), wmctrl(1).
icewm had no known bugs at the time of release. Please report bugs for current versions to the source code repository at Github.
See –copying for full copyright notice and copying permissions.
IceWM is licensed under the GNU Library General Public License.
COPYING file in the distribution or use the –copying flag
to display copying permissions.