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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