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       xdm.options - configuration options for the X display manager


       /etc/X11/xdm/xdm.options contains a set of flags that determine some of
       the behavior of the X display manager xdm(1x).  Most of xdm’s  behavior
       is  customized through other files; consult the xdm manual page if this
       manual page does not describe the behavior you want to alter.

       /etc/X11/xdm/xdm.options may contain comments, which begin with a  hash
       mark  (‘#’)  and  end  at the next newline, just like comments in shell
       scripts.  The rest of the file consists of options which are  expressed
       as  words separated by hyphens, with only one option per line.  Options
       are enabled by simply placing them in the file; they  are  disabled  by
       prefixing the option name with ‘no-’.

       Available options are:

              Normally,  if  the  nologin(5) file exists, its contents will be
              displayed using xmessage(1x) (if xmessage is available), and the
              user  will be returned to the xdm login screen after xmessage is
              dismissed instead of starting the X session.  If this option  is
              enabled,  xdm  starts  a  session  as  usual  (after xmessage is
              dismissed,  if  xmessage  is  available  and  the  nologin  file
              exists).   This  behavior  is  disabled  by  default: nologin is
              heeded, not ignored.

              Enable this option with caution  onproductionmachines;  it
              causes  the  daemon to be stopped and restarted on upgrade, even
              if the process has  children  (which  means  it  is  managing  X
              sessions).   Typically  when a package that contains a daemon is
              being installed or  upgraded,  its  maintainer  scripts  stop  a
              running  daemon  process  before  installing the new binary, and
              restart it after the new  binary  is  installed.   Stopping  xdm
              causes immediate termination of any sessions it manages; in some
              situations this could be an unwelcome  surprise  (for  instance,
              for  remote  xdm  users  who  had  no idea the administrator was
              performing system maintenance).  On the other hand, for machines
              that  stay  up  for long periods of time, leaving the old daemon
              running can be a bad idea if the new version has, for  instance,
              a fix for a security vulnerability (overwriting xdm’s executable
              on the file system has no effect on the copy of xdm in  memory).
              The  xdm  package’s  pre-removal script checks to see if the xdm
              process has any children;  if  it  does,  it  is  possible  that
              someone’s  session would be killed by stopping xdm, so a warning
              is issued and an opportunity to abort  the  upgrade  of  xdm  is
              provided.    Furthermore,  restarting  xdm  on  upgrade  can  be
              surprising, because a locally-managed X server  can  change  the
              active  VT  even while other packages are continuing to upgrade.
              If, by intent or accident, the X server does not honor  the  key
              sequence  to  switch  VTs back to a virtual console, this can be
              undesirable.  This behavior is disabled by default: xdm will  be
              not  be stopped or started during an upgrade of its package; the
              administrator will have to do so by hand (with  invoke-rc.d  xdm
              restart  or  by rebooting the system) before the newly installed
              xdm binary is used.

              Enable this option with caution; it causes the xdm daemon to  be
              started  immediately  after  the  package is installed.  See the
              above  entry  regarding  restart-on-upgrade  for  other  caveats
              regarding  the  consequences  of  starting the xdm daemon during
              package management.  This behavior is disabled by  default:  xdm
              will not be started when it is installed.  Changing this setting
              can affect future installs if the package is  removed,  but  not
              purged (which removes ‘conffiles’, including xdm.options).

              This  option  causes  the /etc/X11/xdm/Xreset script to call the
              sessreg(1x) program to register X sessions managed by xdm in the
              utmp(5) and wtmp(5) files.  If it is disabled, the utmp and wtmp
              files will have no record of xdm  sessions.   This  behavior  is
              enabled by default; sessreg will be used.

       Users  of  older  versions  of  the  Debian system should note that the
       ‘run-xconsole’  option  has  been  removed.   The  shell  script  named
       /etc/X11/xdm/Xreset  can  be edited to disable or modify the running of
       xconsole on the xdm greeter screen; see xdm(1x) for more information.


       Stephen Early, Mark  Eichin,  and  Branden  Robinson  customized  xdm’s
       startup  and  reset scripts and package maintainer scripts to implement
       the functionality described above.  This manual  page  was  written  by
       Branden Robinson.


       sessreg(1x), xmessage(1x), xdm(1x), nologin(5), utmp(5), wtmp(5)