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evmwatch(1)
NAME
evmwatch - Monitors EVM events
SYNOPSIS
evmwatch [-A] [-f filter_expr] [-h hostname[:port_no]]...
[-t show_template] [-w timeout] [-i | -x] [-R reconnect-timeout]
OPTIONS
-A Automatically starts evmshow to produce a formatted display of the
received events.
-f filter_expr
Subscribes for notification of events matching filter_expr. See
EvmFilter(5) for the syntax of filter_expr. By default, the evmwatch
command subscribes for all events.
-h hostname[:port_no]
Attempts to connect to the EVM daemon on the host hostname, rather than
to the local daemon. If a cluster alias is specified for hostname,
attempts to connect to the EVM daemon on that cluster. If specified,
the port number must be the same as the portnum specified in the EVM
daemon configuration file, evmdaemon.conf(4). In most cases, the
default should be used.
If connecting to a cluster alias, evmwatch monitors events that are
posted on all members of the cluster.
If :port_no is specified, port_no is used for TCP communication with
remote clients; otherwise, the evm port number found in /etc/services
is used. If no entry is found in /etc/services, the reserved default
value of 619 is used.
-t show_template
Template string to be passed to evmshow if the -A option is also
specified. If the -A option is not specified, this argument is ignored.
See evmshow(1) for a description of the template string.
-w timeout
Terminates if no event is processed in the time specified by timeout.
The format of timeout is [[[days:]hours:]minutes:]seconds, where days,
hours and minutes can be any integer up to 9999, and seconds can be any
integer up to 9999999. Omitted values are interpreted as zero. If the
converted value exceeds 100,000,000 seconds, it is automatically
reduced to that value with no error being reported. The timer is
restarted each time an event is received.
-i Retrieves copies of all of the registered event templates from the EVM
daemon that match the supplied filter string and for which the user has
access authorization. It writes the templates to stdout as EVM events
and terminates.
-x Terminates with a zero exit value as soon as the first event matching
filter_expr is processed.
-R reconnect-timeout
Specifies the period for which evmwatch should continue to attempt to
reconnect if the connection to the EVM daemon is lost. The format of
reconnect-timeout is [[[days:]hours:]minutes:]seconds, where days,
hours and minutes can be any integer up to 9999, and seconds can be any
integer up to 9999999. Omitted values are interpreted as zero. If the
converted value exceeds 100,000,000 seconds, it is automatically
reduced to that value with no error being reported.
If reconnect-timeout is zero, evmwatch terminates immediately if a
disconnection occurs. If this option is not specified, the reconnection
timeout is set to five minutes for a local connection and 60 minutes
for a remote connection.
OPERANDS
None
DESCRIPTION
The evmwatch command subscribes to the events specified by the filter_expr
and passes all events to its stdout stream as they arrive. Output is in the
form of raw EVM events.
If the -A option is specified, evmwatch automatically starts evmshow and
pipes the event stream into it, producing a formatted display of events. If
a show_template argument is supplied, the specified template string is
passed to evmshow through its own -t option. See evmshow(1) for more
information.
If evmwatch cannot connect to the EVM daemon, it terminates immediately
with an error message. If it succeeds in connecting but subsequently loses
the connection, it attempts to reconnect periodically until the reconnect-
timeout period expires. The retry period is one second for the first
minute, and five seconds thereafter.
RESTRICTIONS
The evmwatch command rejects attempts to output raw events to a terminal
device.
The evmwatch command receives events only for which the user has access
authorization. See evm.auth(4) for details of access authorization.
EXIT STATUS
The following exit values are returned:
0 Successful completion
not 0
An error occurred, including timeout
EXAMPLES
1. The following ksh example watches for all events with a priority of at
least 200 and displays them on stdout. Events are piped automatically
through evmshow to produce a formatted event display.
export EVM_SHOW_TEMPLATE="@timestamp [@priority] @@"
evmwatch -A -f "[pri >= 200]"
2. The following example waits until some other process posts a
particular event and then continues. Redirection of output to
/dev/null implies that the content of the event is of no concern.
evmwatch -f "[name myco.ops.backup.done]" -x >/dev/null
3. The following script builds on the prior example. It waits for five
minutes (300 seconds) for the event to occur or exits as soon as the
event happens.
#! /bin/ksh
evmwatch -f "[name myco.ops.backup.*]" -x -w 300 >/dev/null
if [ $? -eq 0 ]
then
echo Backup completed!
else
echo Backup timed out!
fi
4. The following shell script waits for up to five minutes (300 seconds)
for a pulse event to be received. Each time the pulse arrives, the
timer is reset and evmwatch waits for the next pulse. If the timer
expires, evmwatch terminates with an error code, a warning is
displayed, a high priority event is posted, and the script exits.
#! /bin/ksh
evmwatch -f "[name myco.myapp.remote.pulse]" -w 300 >/dev/null
if [ $? -ne 0 ] then
echo `date` Pulse monitor: No pulse from remote system
evmpost <<END
event {
name myco.myapp.pulsemon.no_pulse
priority 650
}
END
fi
5. The following example monitors all events occurring on a remote host.
If the connection to the remote host is lost, evmwatch attempts to
re-establish the connection for up to three days before terminating.
evmwatch -A -h yoursys -R 3:0:0:0
6. The following example lists the names of all registered events that
the user is authorized to access.
evmwatch -i | evmshow -t "@name" | more
FILES
/etc/services
Definition of the sockets and protocols used for Internet services.
SEE ALSO
Commands: evmget(1), evmpost(1), evmshow(1), evmsort(1), esmd(8)
Files: evmfilterfile(4), services(4)
Event Management: EVM(5)
EVM Events: EvmEvent(5)
Event Filter: EvmFilter(5)
System Administration
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Alphabetical
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