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Linux 2.6 - man page for os_sup (linux section 3erl)

os_sup(3erl)			     Erlang Module Definition			     os_sup(3erl)

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 config-
       ured 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,  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 ver-
	   sion 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 log-
	   ger 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 spe-
	   cific  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 2.2.5 			     os_sup(3erl)


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