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NAME

       xsm - X Session Manager

SYNOPSIS

       xsm [-display display] [-session sessionName] [-verbose]

DESCRIPTION

       xsm  is  a  session  manager.   A  session is a group of applications, each of which has a
       particular state.  xsm allows you to create arbitrary sessions - for  example,  you  might
       have  a "light" session, a "development" session, or an "xterminal" session.  Each session
       can have its own set of applications.  Within a session, you can perform a "checkpoint" to
       save  application state, or a "shutdown" to save state and exit the session.  When you log
       back in to the system, you can load a specific session, and you can delete sessions you no
       longer want to keep.

       Some  session  managers  simply allow you to manually specify a list of applications to be
       started in a session.  xsm is more powerful because it lets you run applications and  have
       them  automatically  become part of the session.  On a simple level, xsm is useful because
       it gives you this ability to easily define which applications are in a session.  The  true
       power  of xsm, however, can be taken advantage of when more and more applications learn to
       save and restore their state.

OPTIONS

       -display display
               Causes xsm to connect to the specified X display.

       -session sessionName
               Causes xsm to load the specified session, bypassing the session menu.

       -verbose
               Turns on debugging information.

SETUP

   .xsession file
       Using xsm requires a change to your .xsession file:

       The last program executed by your .xsession file should be xsm.  With this  configuration,
       when the user chooses to shut down the session using xsm, the session will truly be over.

       Since  the  goal of the session manager is to restart clients when logging into a session,
       your .xsession file, in general, should not directly start up applications.   Rather,  the
       applications  should  be  started  within a session.  When xsm shuts down the session, xsm
       will know to restart these applications.  Note  however  that  there  are  some  types  of
       applications  that  are  not  "session  aware".   xsm  allows  you  to  manually add these
       applications to your session (see the section titled Client List).

   SM_SAVE_DIR environment variable
       If the SM_SAVE_DIR environment variable is defined, xsm will save all configuration  files
       in  this directory.  Otherwise, they will be stored in the user's home directory.  Session
       aware applications are also encouraged to save their checkpoint files in  the  SM_SAVE_DIR
       directory, although the user should not depend on this convention.

   Default Startup Applications
       The  first time xsm is started, it will need to locate a list of applications to start up.
       For example, this list might include a window manager, a session management proxy, and  an
       xterm.   xsm  will  first  look for the file .xsmstartup in the user's home directory.  If
       that file does not exist, it will look  for  the  system.xsm  file  that  was  set  up  at
       installation  time.   Note  that xsm provides a "fail safe" option when the user chooses a
       session to start up.  The fail safe option simply loads the default applications described
       above.

       Each  line in the startup file should contain a command to start an application.  A sample
       startup file might look this:

       <start of file>
       twm
       smproxy
       xterm
       <end of file>

STARTING A SESSION

       When xsm starts up, it first checks to see if the user previously saved any sessions.   If
       no  saved  sessions exist, xsm starts up a set of default applications (as described above
       in the section titled Default Startup Applications).  If at least one  session  exists,  a
       session menu is presented.  The [-session sessionName] option forces the specified session
       to be loaded, bypassing the session menu.

   The session menu
       The session menu presents the user with a list of sessions to choose from.  The  user  can
       change  the  currently selected session with the mouse, or by using the up and down arrows
       on the keyboard.  Note that sessions  which  are  locked  (i.e.  running  on  a  different
       display) can not be loaded or deleted.

       The following operations can be performed from the session menu:

       Load Session          Pressing  this  button  will  load  the  currently selected session.
                             Alternatively, hitting the Return key will also load  the  currently
                             selected  session,  or  the user can double click a session from the
                             list.

       Delete Session        This operation will delete the  currently  selected  session,  along
                             with  all  of  the  application checkpoint files associated with the
                             session.  After pressing this button, the  user  will  be  asked  to
                             press the button a second time in order to confirm the operation.

       Default/Fail Safe     xsm  will start up a set of default applications (as described above
                             in the section titled Default Startup Applications).  This is useful
                             when  the  user  wants  to  start a fresh session, or if the session
                             configuration files were corrupted and the user wants a "fail  safe"
                             session.

       Cancel                Pressing this button will cause xsm to exit.  It can also be used to
                             cancel a "Delete Session" operation.

CONTROLLING A SESSION

       After xsm determines which session to load, it brings up its main window, then  starts  up
       all  applications  that  are part of the session.  The title bar for the session manager's
       main window will contain the name of the session that was loaded.

       The following options are available from xsm's main window:

       Client List       Pressing this button brings up a window containing a list of all clients
                         that are in the current session.  For each client, the host machine that
                         the client is running on is presented.  As clients are added and removed
                         from the session, this list is updated to reflect the changes.  The user
                         is able to control how these clients are restarted (see below).

                         By pressing the View Properties button, the user can  view  the  session
                         management properties associated with the currently selected client.

                         By  pressing the Clone button, the user can start a copy of the selected
                         application.

                         By pressing the Kill Client button, the user can remove  a  client  from
                         the session.

                         By  selecting  a  restart  hint from the Restart Hint menu, the user can
                         control the restarting of a client.  The following hints are available:

                         - The Restart If Running  hint  indicates  that  the  client  should  be
                         restarted  in the next session if it is connected to the session manager
                         at the end of the current session.

                         - The Restart Anyway hint indicates that the client should be  restarted
                         in  the  next  session  even  if  it exits before the current session is
                         terminated.

                         - The Restart Immediately hint is similar to the  Restart  Anyway  hint,
                         but in addition, the client is meant to run continuously.  If the client
                         exits, the session manager  will  try  to  restart  it  in  the  current
                         session.

                         -  The  Restart  Never  hint  indicates  that  the  client should not be
                         restarted in the next session.

                         Note that all X applications may not be "session  aware".   Applications
                         that  are  not  session aware are ones that do not support the X Session
                         Management  Protocol  or  they  can  not  be  detected  by  the  Session
                         Management  Proxy  (see  the  section titled THE PROXY).  xsm allows the
                         user to manually add such applications to the session.   The  bottom  of
                         the  Client List window contains a text entry field in which application
                         commands can be typed in.  Each command should go on its own line.  This
                         information  will  be  saved  with the session at checkpoint or shutdown
                         time.   When  the  session  is  restarted,  xsm   will   restart   these
                         applications in addition to the regular "session aware" applications.

                         Pressing the Done button removes the Client List window.

       Session Log...    The  Session  Log  window presents useful information about the session.
                         For example, when a session is restarted, all of  the  restart  commands
                         will be displayed in the log window.

       Checkpoint        By performing a checkpoint, all applications that are in the session are
                         asked to save their state.  Not every application will save its complete
                         state,  but at a minimum, the session manager is guaranteed that it will
                         receive the command required to restart the application (along with  all
                         command  line  options).   A window manager participating in the session
                         should guarantee that the applications will come back up with  the  same
                         window configurations.

                         If  the  session  being checkpointed was never assigned a name, the user
                         will be required to specify a session name.   Otherwise,  the  user  can
                         perform  the checkpoint using the current session name, or a new session
                         name can be specified.  If the session name  specified  already  exists,
                         the user will be given the opportunity to specify a different name or to
                         overwrite the already existing session.  Note that a  session  which  is
                         locked can not be overwritten.

                         When  performing  a  checkpoint, the user must specify a Save Type which
                         informs the applications in the session how much state they should save.

                         The Local  type  indicates  that  the  application  should  save  enough
                         information  to  restore  the  state as seen by the user.  It should not
                         affect the state as seen by other users.  For example, an  editor  would
                         create  a  temporary file containing the contents of its editing buffer,
                         the location of the cursor, etc...

                         The Global type indicates that the application should commit all of  its
                         data to permanent, globally accessible storage.  For example, the editor
                         would simply save the edited file.

                         The Both type indicates that the application should do  both  of  these.
                         For  example,  the  editor  would  save  the  edited file, then create a
                         temporary file with information such as  the  location  of  the  cursor,
                         etc...

                         In addition to the Save Type, the user must specify an Interact Style.

                         The  None  type  indicates that the application should not interact with
                         the user while saving state.

                         The Errors type indicates that the application  may  interact  with  the
                         user only if an error condition arises.

                         The  Any  type indicates that the application may interact with the user
                         for any purpose.  Note that xsm  will  only  allow  one  application  to
                         interact with the user at a time.

                         After  the  checkpoint  is  completed, xsm will, if necessary, display a
                         window containing the list  of  applications  which  did  not  report  a
                         successful save of state.

       Shutdown          A  shutdown  provides  all  of the options found in a checkpoint, but in
                         addition, can cause the session to exit.  Note that if  the  interaction
                         style  is Errors or Any, the user may cancel the shutdown.  The user may
                         also  cancel  the  shutdown  if  any  of  the  applications  report   an
                         unsuccessful save of state.

                         The  user may choose to shutdown the session with our without performing
                         a checkpoint.

HOW XSM RESPONDS TO SIGNALS

       xsm will respond to a SIGTERM signal by performing a shutdown with the following  options:
       fast,  no  interaction,  save type local.  This allows the user's session to be saved when
       the system is being shutdown.  It can also be used to  perform  a  remote  shutdown  of  a
       session.

       xsm  will  respond  to  a  SIGUSR1  signal  by  performing a checkpoint with the following
       options: no interaction, save type local.  This signal can be used  to  perform  a  remote
       checkpoint of a session.

THE PROXY

       Since  not all applications have been ported to support the X Session Management Protocol,
       a proxy service exists to allow "old" clients to work with the session manager.  In  order
       for  the  proxy  to  detect an application joining a session, one of the following must be
       true:

       - The application maps a top level window containing the WM_CLIENT_LEADER property.   This
       property  provides  a  pointer  to  the  client leader window which contains the WM_CLASS,
       WM_NAME, WM_COMMAND, and WM_CLIENT_MACHINE properties.

       or ...

       - The application maps a top level window which  does  not  contain  the  WM_CLIENT_LEADER
       property.   However, this top level window contains the WM_CLASS, WM_NAME, WM_COMMAND, and
       WM_CLIENT_MACHINE properties.

       An application that support the WM_SAVE_YOURSELF protocol will receive a  WM_SAVE_YOURSELF
       client message each time the session manager issues a checkpoint or shutdown.  This allows
       the application to save state.  If an application does not  support  the  WM_SAVE_YOURSELF
       protocol, then the proxy will provide enough information to the session manager to restart
       the application (using WM_COMMAND), but no state will be restored.

REMOTE APPLICATIONS

       xsm requires a remote execution protocol  in  order  to  restart  applications  on  remote
       machines.   Currently,  xsm  supports  the  rstart  protocol.   In  order  to  restart  an
       application on remote machine X, machine X must have rstart  installed.   In  the  future,
       additional remote execution protocols may be supported.

SEE ALSO

       smproxy(1), rstart(1)

AUTHORS

       Ralph Mor, X Consortium
       Jordan Brown, Quarterdeck Office Systems