NAME

       os_sup - Interface to OS System Messages

DESCRIPTION

       os_sup  is a process providing a message passing service from the operating system to the error logger in
       the Erlang runtime system. It is part of the OS_Mon application, see os_mon(7). Available for Solaris and
       Windows.

       Messages received from the operating system results in an user defined callback  function  being  called.
       This  function  can do whatever filtering and formatting is necessary and then deploy any type of logging
       suitable for the user's application.

SOLARIS OPERATION

       The Solaris (SunOS 5.x) messages are retrieved from the syslog daemon, syslogd.

       Enabling the service includes actions which require root privileges, such as change of ownership and file
       privileges of an executable binary file, and creating a modified  copy  of  the  configuration  file  for
       syslogd. When os_sup is terminated, the service must be disabled, meaning the original configuration must
       be restored. Enabling/disabling can be done either outside or inside os_sup. See Configuration below.

   Warning:
       This  process  cannot  run in multiple instances on the same hardware. OS_Mon must be configured to start
       os_sup on one node only if two or more Erlang nodes execute on the same machine.

       The format of received events is not defined.

WINDOWS OPERATION

       The Windows messages are retrieved from the eventlog file.

       The nteventlog module is used to implement os_sup. See nteventlog(3erl). Note that the start functions of
       nteventlog does not need to be used, as in this case the process is started automatically as part of  the
       OS_Mon supervision tree.

       OS messages are formatted as a tuple {Time, Category, Facility, Severity, Message}:

         Time = {MegaSecs, Secs, MicroSecs}:
           A time stamp as returned by the BIF now().

         Category = string():
           Usually  one  of  "System", "Application" or "Security". Note that the NT eventlog viewer has another
           notion of category, which in most cases is  totally  meaningless  and  therefore  not  imported  into
           Erlang. What is called a category here is one of the main three types of events occurring in a normal
           NT system.

         Facility = string():
           The  source  of  the  message,  usually  the name of the application that generated it. This could be
           almost any string. When matching messages from  certain  applications,  the  version  number  of  the
           application may have to be accounted for. This is what the NT event viewer calls "source".

         Severity = string():
           One  of  "Error",  "Warning",  "Informational",  "Audit_Success",  "Audit_Faulure"  or,  in case of a
           currently unknown Windows NT version "Severity_Unknown".

         Message = string():
           Formatted exactly as it would be in the NT eventlog viewer. Binary data is not imported into Erlang.

CONFIGURATION

         os_sup_mfa = {Module, Function, Args}:
           The callback function to use. Module and Function are atoms and Args is a list of terms. When  an  OS
           message Msg is received, this function is called as apply(Module, Function, [Msg | Args]).

           Default  is  {os_sup,  error_report,  [Tag]}  which  will  send  the  event to the error logger using
           error_logger:error_report(Tag, Msg). Tag is the value of os_sup_errortag, see below.

         os_sup_errortag = atom():
           This parameter defines the error report type used when messages are sent to error  logger  using  the
           default  callback  function. Default is std_error, which means the events are handled by the standard
           event handler.

         os_sup_enable = bool():
           Solaris only. Defines if the service should be  enabled  (and  disabled)  inside  (true)  or  outside
           (false)  os_sup.  For  backwards compatibility reasons, the default is true. The recommended value is
           false, as the Erlang emulator should normally not be run with root privileges,  as  is  required  for
           enabling the service.

         os_sup_own = string():
           Solaris  only.  Defines  the  directory  which  contains  the  backup  copy  and  the Erlang specific
           configuration files for syslogd, and a named pipe to receive the messages from  syslogd.  Default  is
           "/etc".

         os_sup_syslogconf = string():
           Solaris   only.   Defines   the  full  name  of  the  configuration  file  for  syslogd.  Default  is
           "/etc/syslog.conf".

EXPORTS

       enable() -> ok | {error, Res}
       enable(Dir, Conf) -> ok | {error, Error}

              Types:

                 Dir = Conf = Res = string()

              Enables the os_sup service. Needed on Solaris only.

              If the configuration parameter os_sup_enable is false, this function is  called  automatically  by
              os_sup, using the values of os_sup_own and os_sup_syslogconf as arguments.

              If  os_sup_enable  is  true,  this  function  must  be called before OS_Mon/os_sup is started. Dir
              defines the directory which contains the backup copy and the Erlang specific  configuration  files
              for  syslogd,  and  a  named  pipe  to receive the messages from syslogd. Defaults to "/etc". Conf
              defines the full name of the configuration file for syslogd. Default is "/etc/syslog.conf".

              Results in a OS call to:

              <PRIVDIR>/bin/mod_syslog otp Dir Conf

              where <PRIVDIR> is the priv directory of OS_Mon, code:priv_dir(os_mon).

              Returns ok if this yields the expected result "0", and {error, Res} if it yields anything else.

          Note:
              This function requires root privileges to succeed.

       disable() -> ok | {error, Res}
       disable(Dir, Conf) -> ok | {error, Error}

              Types:

                 Dir = Conf = Res = string()

              Disables the os_sup service. Needed on Solaris only.

              If the configuration parameter os_sup_enable is false, this function is  called  automatically  by
              os_sup, using the same arguments as when enable/2 was called.

              If os_sup_enable is true, this function must be called after OS_Mon/os_sup is stopped. Dir defines
              the  directory  which  contains  the  backup  copy and the Erlang specific configuration files for
              syslogd, and a named pipe to receive the messages from syslogd. Defaults to "/etc".  Conf  defines
              the full name of the configuration file for syslogd. Default is "/etc/syslog.conf".

              Results in a OS call to:

              <PRIVDIR>/bin/mod_syslog nootp Dir Conf

              where <PRIVDIR> is the priv directory of OS_Mon, code:priv_dir(os_mon).

              Returns ok if this yields the expected result "0", and {error, Res} if it yields anything else.

          Note:
              This function requires root privileges to succeed.

SEE ALSO

       error_logger(3erl), os_mon(3erl)

       syslogd(1M), syslog.conf(5) in the Solaris documentation.

Ericsson AB                                       os_mon 2.8.2                                      os_sup(3erl)