Index: /trunk/src/VBox/Installer/linux/VBoxHeadlessXOrg.sh
===================================================================
--- /trunk/src/VBox/Installer/linux/VBoxHeadlessXOrg.sh	(revision 43795)
+++ /trunk/src/VBox/Installer/linux/VBoxHeadlessXOrg.sh	(revision 43796)
@@ -81,5 +81,7 @@
 The optional configuration file should contain a series of lines of the form
 "KEY=value".  It will be read in as a command shell sub-script.  Here is the
-current list of possible key settings with a short explanation.
+current list of possible key settings with a short explanation.  Usually it
+should be sufficient to change the value of \${HEADLESS_X_ORG_USERS} and to
+leave all other settings unchanged.
 
   HEADLESS_X_ORG_CONFIGURATION_FOLDER
@@ -100,8 +102,18 @@
     repeated at regular intervals until it returns successfully, so a command
     which can be executed internally be the shell (like "[") is preferable.
+    The default command waits until the udev event queue has settled.
+
+  HEADLESS_X_ORG_USERS
+    List of users who will have access to the X servers started and for whom we
+    will provide the configuration details via VirtualBox extra data.  This
+    variable is only used by the commands in the default configuration
+    (\${HEADLESS_X_ORG_SERVER_PRE_COMMAND} and
+    \${HEADLESS_X_ORG_SERVER_POST_COMMAND}), and not by the service itself.
 
   HEADLESS_X_ORG_SERVER_PRE_COMMAND
     Command to execute once to perform any set-up needed before starting the
-    X servers, such as setting up the X server authentication.
+    X servers, such as setting up the X server authentication.  The default
+    command creates an authority file for each of the users in the list
+    \${HEADLESS_X_ORG_USERS}.
 
   HEADLESS_X_ORG_SERVER_COMMAND
@@ -112,6 +124,11 @@
       HEADLESS_X_ORG_SERVER_COMMAND="Xorg :\${screen} [...] > \"\${log_file}\"
 
+  HEADLESS_X_ORG_SERVER_POST_COMMAND
+    Command to execute once the X servers have been successfully started.  By
+    default this stores the service configuration information to VirtualBox
+    extra data for each of the users in the list \${HEADLESS_X_ORG_USERS}.
+
   HEADLESS_X_ORG_SERVER_LOG_FILE_TEMPLATE
-    The default X server log file name, containing the variable "${screen}" for
+    The default X server log file name, containing the variable "\${screen}" for
     the screen number.  The variable must be quoted for expansion at evaluation
     time, e.g.
@@ -125,7 +142,7 @@
 HEADLESS_X_ORG_LOG_FILE="${SERVICE_NAME}.log"
 HEADLESS_X_ORG_RUN_FOLDER="/var/run/${SERVICE_NAME}"
-HEADLESS_X_ORG_CHECK_PREREQUISITES="[ -e /dev/dri/card0 ]"
+HEADLESS_X_ORG_CHECK_PREREQUISITES="udevadm settle || ! udevadm -V"
 X_AUTH_FILE="${HEADLESS_X_ORG_RUN_FOLDER}/xauth"
-HEADLESS_X_ORG_SERVER_PRE_COMMAND="echo > \"${X_AUTH_FILE}\"; xauth -f \"${X_AUTH_FILE}\" add :0 . \"\$(dd if=/dev/urandom count=1 bs=16 2>/dev/null | od -An -x)\""
+HEADLESS_X_ORG_SERVER_PRE_COMMAND="echo > \"${X_AUTH_FILE}\"; xauth -f \"${X_AUTH_FILE}\" add :0 . \"\$(dd if=/dev/urandom count=1 bs=16 2>/dev/null | od -An -x)\"; for i in ${HEADLESS_X_ORG_USERS}; do cp \"${X_AUTH_FILE}\" \"${X_AUTH_FILE}.${i}\"; chown \"${i}\" \"${X_AUTH_FILE}.${i}\"; done"
 HEADLESS_X_ORG_SERVER_COMMAND="Xorg :\${screen} -auth \"${HEADLESS_X_ORG_RUN_FOLDER}/xauth\" -config \"\${conf_file}\" -logverbose 0 -logfile /dev/null -verbose 7 > \"\${log_file}\" 2>&1"
 HEADLESS_X_ORG_SERVER_LOG_FILE_TEMPLATE="Xorg.\${screen}.log"
@@ -245,3 +262,7 @@
   space=" "
 done
+
+# Do any post-start work.
+eval "${HEADLESS_X_ORG_SERVER_POST_COMMAND}"
+
 wait
Index: /trunk/src/VBox/Installer/linux/testcase/tstHeadlessXOrg.sh
===================================================================
--- /trunk/src/VBox/Installer/linux/testcase/tstHeadlessXOrg.sh	(revision 43795)
+++ /trunk/src/VBox/Installer/linux/testcase/tstHeadlessXOrg.sh	(revision 43796)
@@ -264,2 +264,38 @@
 expect_exit "${PID}" 5 test_pre_command
 rm -f "${XORG_FOLDER}"/xorg.conf.* "${TEST_FOLDER}"/run/pre*
+
+# Set up our post-command test configuration file.
+create_basic_configuration_file "${TEST_FOLDER}/conf" "${TEST_FOLDER}"
+cat >> "${TEST_FOLDER}/conf" << EOF
+HEADLESS_X_ORG_SERVER_COMMAND="rm -f \"${TEST_FOLDER}/run/post\""
+HEADLESS_X_ORG_SERVER_POST_COMMAND="touch \"${TEST_FOLDER}/run/post\""
+EOF
+
+# Post-command test.
+print_line "post-command test"
+touch "${XORG_FOLDER}/xorg.conf.2"
+touch "${XORG_FOLDER}/xorg.conf.4"
+
+test_post_command()
+{
+  STATUS="$1"
+  case "${STATUS}" in
+  0)
+    LOG_FOLDER="${TEST_FOLDER}/log"
+    LOG="${LOG_FOLDER}/log"
+    if [ -e "${TEST_FOLDER}/run/post" ]; then
+      printf "SUCCESS.\n"
+    else
+      printf "\nFAILED: post-command not executed.\n"
+    fi
+    ;;
+  *)
+    printf "\nFAILED: exit status ${STATUS}.\n"
+  esac
+}
+
+rm -f "${TEST_FOLDER}/run/post"
+./VBoxHeadlessXOrg.sh -c "${TEST_FOLDER}/conf" &
+PID=$!
+expect_exit "${PID}" 5 test_post_command
+rm -f "${XORG_FOLDER}"/xorg.conf.* "${TEST_FOLDER}/run/post"