EVM man page on HP-UX

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EVM(5)									EVM(5)

       EVM - event management

   Introduction to Events and Event Management
       The purpose of an event management system is to provide a means for any
       system component or application to indicate that something has happened
       that  may be of interest to some other entity.  The indication is known
       as an event, and the component posting the event is known as  an	 event
       generator  or event poster.  The entity interested in the indication is
       known as an event subscriber.

       When a system component has something interesting to report,  it	 makes
       the  information	 available  through  an event channel.	The term event
       channel describes any facility used to publish or retrieve event infor‐
       mation, and might refer to any of the following:

	 ·  A simple log file

	 ·  An event management system

	 ·  A  program that can be run to obtain a snapshot of status informa‐

       An event management system is an active event channel, and as  such  it
       provides services for distributing, storing and retrieving event infor‐

       The HP-UX system logger, syslog, is an example of an  event  management
       system.	 It  provides  a  simple event distribution facility for other
       components to use, and its daemon actively manages the  event  informa‐
       tion it receives.  By contrast, the daemon's log file, is an example of
       a passive event channel.	 The daemon simply writes new  event  informa‐
       tion  to	 the  end  of  its file, and takes no special action to notify
       interested entities when it does so.

       In general, an event poster is unaware of any entities  that  might  be
       interested in its event information.  It simply uses an available event
       channel to post the event.  It is the responsibility of the event chan‐
       nel  to decide how to make the event available, and to whom.  The event
       subscriber is responsible for identifying an interest in events to  the
       event  channel.	 A  subscriber might be a user-level process, a kernel
       subsystem, or (through some utility program) a user.

   About EVM
       The Event Manager (EVM) is  a  comprehensive  event  management	system
       that,  in  addition to providing traditional event handling facilities,
       unifies events from many channels to provide a  system-wide  source  of
       information.   For  information	about  using  EVM  as an aid to system
       administration, see the

   The EVM Event
       An EVM event is a package of information that  can  be  passed  between
       programs	 and stored in files.  The underlying format of an event pack‐
       age is binary, but supplied commands and programming interfaces can  be
       used to extract and display the information contained in an event.  The
       term raw event is used to refer to an event in its binary state,	 while
       an event that has been converted to text form for display is said to be

       An EVM event may contain any or all of a set  of	 standard  event  data
       items,  including  (but	not  limited to) an event name, a timestamp, a
       priority value and some message text.  An event may also carry any num‐
       ber of named variable data items, each of which can hold further infor‐
       mation about the event.	EVM events can carry events from  other	 chan‐
       nels, such as the binary error logger, by holding them in variable data

       Full details of the EVM event are provided in the EvmEvent(5) manpage.

   The EVM Daemon
       The EVM daemon, is started automatically when the system is initialized
       to  level 2.  The daemon provides posting and notification services for
       system and application clients running on the local system.   Refer  to
       the evmd(1M) and evmdaemon.conf(4) manpages for more information.

   The EVM Logger
       The EVM logger, is an event subscriber that is started automatically by
       the daemon.  The logger reads its configuration file to	establish  the
       set  of	events	to  be logged, subscribes for those events, and stores
       them in managed logfiles as they arrive.	 By default, the  logger  also
       displays high priority events on the system console, and mails informa‐
       tion about them to the root user.  The logger can be configured to man‐
       age  any number of logfiles, each with its own selection of events, and
       to execute user-supplied commands on receipt of selected events.

       For more information refer to the evmlogger(1M)	and  evmlogger.conf(4)

   The EVM Channel Manager
       The EVM channel manager, is started automatically by the daemon, and is
       responsible for managing time-based event channel functions.  The chan‐
       nel  manager  reads the EVM channel configuration file and periodically
       runs event monitoring commands for  any	configured  passive  channels.
       The  program also is responsible for running daily logfile cleanup com‐

       The channel manager and the channel configuration file are described in
       the evmchmgr(1M) and evmchannel.conf(4) manpages.

   Command Line Utilities
       EVM's  system  administration  facilities include a set of command line
       utilities that can be used from the command line or in shell scripts to
       post  events, to monitor event activity, to retrieve stored events from
       log files, and to sort and view events in a variety of ways.  The util‐
       ities  are  designed  to be used together in shell pipelines.  For more
       information refer  to  the  evmpost(1),	evmwatch(1),  evmget(1),  evm‐
       sort(1), and evmshow(1) manpages.

   Filtering Events
       Because	a system may generate many events over the course of a day, it
       is often desirable to limit your view to the particular	set  in	 which
       you are interested.  For example, you may want to see the events posted
       by one particular subsystem, or all events with a high priority	value.
       EVM  events can be selected by using an event filter which is a charac‐
       ter string that describes the selection using a predefined filter  syn‐
       tax.   You  can use a filter to select events according to several dif‐
       ferent criteria, including event name, timestamp, priority and the name
       of the posting system.

       You  can use an event filter by specifying the option to several of the
       EVM command line utilities.  The EVM logger uses event filters  in  its
       configuration  file  to	select	the  actions to be taken when specific
       events occur.  Frequently-used event filters can be  stored  in	filter
       files for easy reference.

       For  details  of	 the  event filter syntax and the use of filter files,
       refer to the EvmFilter(5) and evmfilterfile(4) manpages.

   Event Template Files
       Event template files are used to control the set of events that can  be
       posted  on  a given system, and to provide a central source for much of
       the information that is carried in a given  event.   For	 example,  the
       priority	 and  message text for a given event are likely to be the same
       each time the event is posted, and centralizing this information	 makes
       it  much easier to see and maintain than if the information was held in
       the posting program or the kernel.

       An event template file is a text file that holds	 template  information
       for one or more named events.  A template file must be installed before
       the events it describes can be posted, and is read by  the  EVM	daemon
       each  time  the	daemon	starts	or reloads its configuration.  When an
       event is posted, the daemon adds the information held in	 the  template
       to the posted event before distributing it to subscribers.

       For more information about the purpose and the syntax of template files
       see the evmtemplate(4) manpage.

   Event Authorization
       Because the unrestricted ability to  monitor  or	 post  certain	events
       could compromise security in some environments, EVM provides a means of
       restricting the ability to post and access selected events to  specific
       authorized  users.   Refer to the evm.auth(4) manpage for more informa‐

   The EVM Programming Interface
       The EVM application programming interface (API) library,	 provides  all
       the  functions  required for an application program to create, post and
       subscribe for events, to read and write them from and to standard  file
       descriptors,  and  to manipulate their contents.	 For a full discussion
       of programming with EVM, refer to the and the manpages for the routines
       listed in the section.

       EVM supports event posting and subscription in kernel space through the
       pseudo-device driver

       evmget(1), evminfo(1), evmpost(1), evmshow(1), evmsort(1), evmwatch(1),
       evmchmgr(1M),  evmd(1M),	 evmlogger(1M),	 evmreload(1M),	 evmstart(1M),

       EvmConnControl(3),   EvmConnCreate(3),	EvmConnSubscribe(3),   EvmCon‐
       nWait(3),    EvmEventCreate(3),	 EvmEventDump(3),   EvmEventFormat(3),
       EvmEventPost(3),	 EvmEventRead(3),  EvmEventValidate(3),	 EvmFilterCre‐
       ate(3),	 EvmItemSet(3),	  EvmSrvStart(3),   EvmStatusTextGet(3),  Evm‐

       evm.auth(4), evmchannel.conf(4),	 evmdaemon.conf(4),  evmfilterfile(4),
       evmlogger.conf(4), evmtemplate(4).


   Event Callback

   Event Connection

   EVM Events

   Event Filter


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