dtsession [-norestore] [-session session_name]
The dtsession client provides X11R6 XSMP and (by proxy) ICCCM 1.1 compliant session management functionality during a user session, which is the time from login to logout. It launches a window manager and allows for saving a session, restoring a session, locking a session, launching screen savers and allocating colors for desktop compatible clients.
The dtsession client supports the following key tasks:
A session is the collection of applications, settings and resources that are present on the user’s desktop. Session management is a set of conventions and protocols that allow a special session manager such as dtsession to save and restore a user’s session. A user is able to log into their system and be presented with the same set of running applications, settings and resources as were present when the user logged off. When a user logs into the desktop for the first time, a default initial (new user) session is loaded. Afterward, dtsession supports the notion of a current, a home, and a display-specific session, which may be either current or home.
When a user logs into the desktop for the first time, dtsession will generate the user’s initial session using system default values. The initial session is sometimes referred to as the "new user" session. Refer to Session Resource Management and Session Application Management for more information.
The user’s running session is always considered the current session, whether restored upon login from a saved home session, a saved current session or the system default initial session. Based on the user’s Style Manager Startup settings, when the user exits the session, the current session is automatically saved. When the user next logs into the desktop, dtsession allows the user to select the previously saved current session as the session to start. This means that the desktop will be restored to the same state it was in when the user last logged out.
Another option is having the desktop be restored to the same state every time the user logs in, regardless of its state when the user logged out. The user may save the state of the current session, then via the Style Manager Startup settings, have the desktop start that session every time the user logs in. Alternatively, dtsession will allow the user to select the home session as the session to start at login.
To run a specific session for a specific display, a user can create a display-specific session. To do this, the user can copy the $HOME/.dt/sessions directory to the $HOME/.dt/sessions/display directory where display is the real, unqualified hostname (for example, pablo:0 is valid, pablo.gato.com:0 or local:0 is not). When the user logs in, dtsession will allow the user to select a display-specific home or current session as the session to start. Dtsession will actually launch the session only if it is compatible with the user’s login display.
For an application to be saved upon logout and restarted upon login, it must participate in a simple session management protocol. dtsession supports the X11R6 XSMP Session Management Protocol.
Applications that wish to save their state can take part in the WM_SAVE_YOURSELF protocol. To do this, an application needs to set the WM_SAVE_YOURSELF property on one and only one of its top-level windows. When the user presses the Set Home Session button in the Style Manager, dtsession sends a SaveYourself message to the top-level window of each of its clients. The message sets the save-type to Local, shutdown to 0, interact-style to None and fast to 0.
When an application receives the message, it sends a SaveYourselfPhase2Request message to the Session Manager, which will reply with a SaveYourselfPhase2 message. Only when the Window Manager receives the SaveYourselfPhase2 message will it save its state. The information saved by the Window Manager for each of its client’s set of windows will include: geometry, icon state and workspace.
If interact-style on the initial SaveYourself message is None, the application cannot interact with the user in any way as it is saving its state. If it is Any, the application can interact with the user for any purpose. This includes the ability to de-iconify itself, as well as to change its current workspace. To minimize confusion, the Session Manager issues a ToolTalk message to the Window Manager requesting the recommended order to interact. The Window Manager responds with the list of SM_CLIENT_IDs and their associated workspace numbers in workspace order. After receiving an Interact message (with interact-style set to Any), an application should go system-modal to prevent other, less well-behaved non-interacting applications from allowing user interaction while the application is interacting with its user.
Because an application will usually save its state into a file, the Session Manager provides DtSessionSavePath as a convenience function that returns a full pathname of a file in which an application can save its state. While the application is saving its state, dtsession awaits notice from the application that it is done. To tell dtsession that the state save is complete, the application updates the WM_COMMAND property on its top-level window.
The WM_COMMAND property on an application’s top-level window serves two purposes. First, a change of this property is the indication to dtsession that an application is done saving its state and dtsession can proceed to the next application. Second, the WM_COMMAND property value is expected to contain the command line that dtsession will use to restart the application at session startup. If an application is launched with a full pathname, then it should use the full pathname when setting WM_COMMAND. Applications that do not need to save their state, but wish to be restarted, can simply set WM_COMMAND during application startup and forget about it.
Refer to the XmAddWmProtocols, XmAddWMProtocolCallback, and XSetCommand APIs for more information.
In addition to the "save-yourself" client session management support, the X11R6 XSMP protocol provides the following features (which are not found in the ICCCM protocol):
dtsession implements the X11R6 XSMP session management protocol and provides backward compatibility by acting as a proxy for client applications that continue to use the older ICCCM session management protocol.
At session startup time, dtsession presents a dialog that allows the user to select which of the following sessions to start:
Although a user’s list of sessions is not known until after the user logs in, the dialog presents all of the session choices. If a user selects a session that does not exist, dtsession takes the following actions. If the user selects:
If the user selects a display-specific session and one does not exist, dtsession posts a warning dialog stating that a new session will be created. The warning dialog contains three buttons:
The session manager uses the X Server RESOURCE_MANAGER property on which to make available desktop resources to all applications. The session manager will load the RESOURCE_MANAGER in the following manner:
The desktop default resources can be found in /usr/dt/config/$LANG/sys.resources. These resources will be made available to each user’s session via the RESOURCE_MANAGER property. This file should not be edited as it will be unconditionally overwritten upon subsequent desktop installations.
A system administrator may augment the system default resources by creating /etc/dt/config/$LANG/sys.resources. In this file, a system administrator may override system default resources or specify additional resources. As this file is merged into the desktop default resources during session startup, it is preferable that only new or updated resource specifications be placed in this file, rather than a copy being made of the desktop default resource file. Resources specified in this file will be made available to each user’s session via the RESOURCE_MANAGER property. Resources specified in this file take precedence over those specified in the desktop default resource file.
A user may augment the desktop default and system administrator resources via their $HOME/.Xdefaults file. Resources specified in this file will be made available to only that user’s session via the RESOURCE_MANAGER property. Resources specified in this file take precedence over those specified in the desktop default or system administrator resource files.
Note:The X Toolkit Intrinsics specifies that it will load resources for an application from either RESOURCE_MANAGER or from $HOME/.Xdefaults, but not both. Ordinarily, this would mean that the user’s $HOME/.Xdefaults file would be ignored. However, the session manager accommodates $HOME/.Xdefaults by merging it into the RESOURCE_MANAGER at session startup as described above. If a user changes $HOME/.Xdefaults, the changes will not be visible to new applications until the user invokes the ReloadResources action.
The ReloadResources action will instruct the session manager to reload the RESOURCE_MANAGER with the system, system administrator, and user specified resources. This is useful to make available to new applications changes made to system administrator or user specified resource files.
See also dtresourcesfile(4) and dtsessionaction(5) .
At session startup, the session manager will restart any applications that were saved as part of the session. The system default set of applications to be restored as part of the user’s Initial Session can be found in /usr/dt/config/$LANG/sys.session. This file should not be edited as it will be unconditionally overwritten upon subsequent desktop installations.
See also dtsessionfile(4) .
A system administrator may replace the set of applications that are restored as part of the user’s Initial Session by creating a file named /etc/dt/config/$LANG/sys.session. Unlike the resource files, this file will be used as a complete replacement for the desktop default file, so it is valid to make a copy of the system default file and make any necessary modifications.
The Session Manager uses ICE-based authentication as described in the Inter-Client Exchange (ICE) Library v1.0.
The Session Manager is built with a table of available authentication protocols. Selection of the protocol is done via the AuthName resource. The AuthName default is the string MIT-MAGIC-COOKIE-1. The Session Manager supports the same protocols as the Login Manager.
dtsession is responsible for starting the window manager. By default /usr/dt/bin/dtwm is started. An alternate window manager can be specified with the wmStartupCommand resource. Refer to the Workspace Manager specification for more information.
The style manager provides the interface by which a user can change various desktop and X server settings for the current session. Refer to the Style Manager specification for more information.
dtsession serves as the color server for the desktop and provides a set of resources that can be used to configure it. The foregroundColor resource controls whether a pixel is allocated for the foreground color. The dynamicColor resource specifies whether read-only colors are allocated. The shadowPixmaps resource specifies whether colors are allocated for top shadow or bottom shadow. The colorUse resource limits color allocation. Finally, the writeXrdbColors resource specifies whether the *background and *foreground resources are placed in the resource database. See the Color Server Resources section for more information.
The CDE desktop makes use of a color sharing protocol between dtsession and the rest of the desktop (dtstyle in particular) and Motif. This protocol allows:
The color sharing protocol involves:
A Color Set is a set of five colors that are used to represent a single logical color in the Motif toolkit. For each background color (the logical color), there are associated top shadow, bottom shadow, foreground, and select colors, all generated from the background color. These associated colors are the mechanism for giving widgets their 3-D appearance.
A Color Palette is a named set of a maximum of eight background colors. A single palette is used to color the desktop components. A list of default palettes is provided from which the user can select. The user can also add and delete palettes, as well as modify an existing palette.
dtsession, the color server, uses ICCCM X Selection based mechanisms to communicate color use, palette and color set pixel information to the desktop clients.
The name of the (CUSTOMIZE_DATA) selection is the atom Customize Data:i, where i is the screen number.
The names of the targets are the atoms Type Of Monitor and Pixel Sets.
The Type Of Monitor target is used to convey color settings to the desktop clients, such as dtstyle or the Motif toolkit, that need this information. The content corresponds to the value of the dtsession color usage resources.
When asked to convert the screen Customize Data:i selection to the target Type Of Monitor, the format and content encoding used is the following:
This information, especially dynamicColor, is currently used only by dtstyle in CDE to implement the color manager GUI.
The Pixel Sets target is used to convey palette and color set pixel information to the desktop clients. The content is always 8 color set values, but depending on the color usage settings, some entries will be the duplicated. For the receiver of this information, however, it simply means it can access the index as specified in the high color scheme.
When asked to convert the screen Customize Data:i selection to the target Pixel Sets, the format used is the following:
The mapping between color set Ids and colorUse is as follows:
For each color set, the cell allocation scheme is the following (dynamicColor determines if the pixels are allocated read/write or read-only):
| colorUse |
| HIGH_COLOR |
| HIGH_COLOR |
| HIGH_COLOR |
| HIGH_COLOR |
| MEDIUM_COLOR |
| MEDIUM_COLOR |
| MEDIUM_COLOR |
| MEDIUM_COLOR |
| LOW_COLOR |
| LOW_COLOR |
| LOW_COLOR |
| LOW_COLOR |
| B_W |
Dtsession provides session locking. The current session can be locked directly by pressing the lock icon on the front panel. If supported by the X server, the current session can be locked after a specified period of inactivity. To unlock the session, the user must enter their login password.
By default, dtsession supports traditional local UNIX authentication for unlocking the session. Additional re-authentication functions such as those required by DCE may be added by individual vendors.
Dtsession provides support for the launching of external screen savers as a part of session locking from the front panel or, if supported by the X server, after a specified period of inactivity. Refer to the Screen Saver specification for information as to how screen savers are integrated into the desktop.
Dtsession’s ability to provide session lock or screen saver launch after a specified period of inactivity depends upon the availability of an X server screen saver extension. dtsession supports two such extensions:
The ability of dtsession to recognize both, either or none of these extensions is vendor specific.
dtsession should be launched from the Xsession script. Xsession is described in the login manager specification. It is recommended that Xsession be launched from dtlogin as part of the login sequence as the default, but there are alternative methods of starting Xsession:
If you must start a service after login but before the Session Manager (for example, an input method server), start the service by placing a script in the fdirectory /usr/dt/config/Xsession.d.
To avoid being restarted by the Session Manager when a session is started, a service that must be started before the Session Manager should explicitly set the RestartStyleHint property to RestartNever (possibly by setting an Xt resource).
The dtsession client is automatically invoked by the DT Login Manager (dtlogin). If desired, dtsession may also be started on an existing X server. Note that dtsession automatically starts a window manager.
The following options are available:
Exit values are:
Start session manager from command line without restoring previous session.
| Name |
| colorUse |
| dynamicColor |
| foregroundColor |
| shadowPixmaps |
| writeXrdbColors |
| Name |
| keys |
| passwordTimeout |
| Name |
| AuthName |
| IgnoreEnvironment |
| queryServerSettings |
| NumSessionsBackedup |
| saveFontPath |
| wmStartupCommand |
This resource specifies the authentication protocol that dtsession is to use. The default is the string MIT-MAGIC-COOKIE-1. dtsession supports the same protocols as dtlogin.
This resource specifies the number of colors to use for the user interface. Valid types are: Color server will determine type of monitor based upon number of display planes of the screen as follows:
This resource can have values of True or False. dynamicColor is used to reduce the number of color cells being used. Once a palette has been selected and it is not likely to be changed, dynamicColor can be set to False. If set to False colors cannot be dynamically changed using the DT style manager. A selected palette will take effect the next session. The next time the session comes up, the color server uses Read Only color cells that can be shared by all clients, thus reducing the number of color cells used.
This resource can have values of White, Black or Dynamic. ForegroundColor causes all text (foreground) to use either pixel 0 or 1 (Black or White) or to have a color cell dedicated to foreground and changes in response to the background color (Dynamic) for each ColorSet. If set to White or Black, the number of color cells used per ColorSet is reduced by 1.
This resource is a list of keyholders who have the ability to unlock the screen any time it is locked by the user. The list is a list of user id’s separated by commas. For example if user kim has the following resource active during a session:
This resource specifies (in seconds) the amount of time before the password dialog is removed from the screen. When the display is locked, the pointer shows a lock cursor, and a dialog appears which asks for the user password. If no activity from the pointer or keyboard is detected for passwordTimeout seconds, the dialog is removed from the screen. The dialog is redisplayed as soon as a pointer or keyboard event is detected. An passwordTimeout of 0 leaves the password dialog in place for the entire time the display is locked. The default value is 10 seconds.
This resource specifies whether dtsession queries the server at logout for all its settings or saves only those settings set by using the DT Style Manager. Querying the server ensures that all settings are saved; however, there is a degradation in performance when a full query is done. The default value is False, which means that the server will not be queried.
This resource specifies the number of checkpoints to keep. When the number of checkpoints for a session exceeds this value, the DiscardCommand properties for the oldest session will be executed and the oldest checkpoint will be removed. The default is 2.
For color systems, this resource can have a value of True or False. If True, topShadowColor and bottomShadowColor use the same pixel as background and topShadowPixmap and bottomShadowPixmap are specified instead of solid color to create the 3D look. This reduces the number of color cells per ColorSet by 2. ShadowPixmaps defaults to True for systems with 4 or less color planes (16 or less color cells), and False for systems with more than 4 color planes.
This resource allows for an alternate window manager to be started at login. If this resource is NULL, dtsession starts /usr/dt/bin/dtwm. An alternate startup might look like: Dtsession*wmStartupCommand: /usr/bin/X11/mwm
Note:The command should not have any commands to a shell in it, and that it should not be surrounded by quotes. Also, if any other window manager other than dtwm is used, clients will be restored, but may not be restored to the correct position. By default, this resource contains a NULL value.
See related specifications: