EvmFilter(5)

NAME

EvmFilter — EVM (Event Management) event filter

DESCRIPTION

An event filter is a specification of a set of interesting events. Event subscribers use filters to tell the EVM daemon which events they want to receive. For example, one subscriber may be only interested in receiving events reporting hardware errors, while another may want to receive all high-priority events, regardless of what they are reporting. If a subscriber does not set a filter, it will receive no events.

The Event Viewer and some of the EVM user commands also use filters to select events for viewing or processing.

A filter is an ASCII character string. It can be very simple or arbitrarily complex. Complex filters are created by combining simple filters.

A simple filter has the following format:

[keyword expr] | all | 1 |  none | 0 

The format of expr is specific to the type of filter. The left and right square brackets ([ and ]) are required. Keywords may be specified in any mix of upper and lower case, and where the underscore character (_) is included in a full-length keyword (as in host_name), it may be omitted. Keywords may be abbreviated, and in the following paragraphs the minimum abbreviation for each is indicated by upper-case letters.

Possible values for keyword and the associated expr are as follows:

Name event-name-specifier

Selects events with a name matching the event-name-specifier. Names are considered to match when the event name matches as many components as included in the filter.

The event-name-specifier may include the * and the ? characters as wildcards in any component position. The * represents 0 or more components with any value. The ? represents exactly one component. Any event-name-specifier includes an implied trailing .* wildcard.

Priority equality-operator integer

Only events with a priority meeting the specified evaluation will be passed. The integer value may be 0 to 700, inclusive. See the following table for a description of equality-operator. May be specified as prio.

Timestamp time-range-specifier

All events with a timestamp that is within the time-range-specifier are passed. See the description of time-range-specifier. May be specified as time.

Age equality-operator age-specifier

Selects events that meet the age specification. See the description of age-specifier. The equality-operator must specify less-than or less-than-or-equal, meaning "newer than", or greater-than or greater-than-or-equal, meaning "older than." The equal or not equal operators are not allowed.

BEFore absolute-time-specifier

All events with a timestamp that is earlier than the absolute-time-specifier are passed. See the description of absolute-time-specifier.

SINce absolute-time-specifier

All events with a timestamp that is equal to or later than the absolute-time-specifier are passed. See the description of absolute-time-specifier.

EVent_id equality-operator integer

All events with an event_id meeting the specified evaluation will be passed. See EvmEvent(5) for a description of the event_id. See the following table for a description of equality-operator. The EVent_id keyword may be abbreviated to ID.

NONE or 0: A filter value of none or 0 (zero) passes no events.
ALL or 1: A filter value of all or 1 passes all events.

The available equality-operator specifiers and their alternate representations are shown in the following table. The alternate representations may be used in any mix of upper and lower case.

Operator	Alternate	Meaning
`=`	eq	Equal
`>`	gt	Greater Than
`<`	lt	Less Than
`>=`	ge	Greater Than or Equal
`<=`	le	Less Than or Equal
`!=`	ne	Not Equal

An age-specifier comprises an integer value followed immediately by one of the letters w (weeks), d (days), h (hours), m (minutes) or s (seconds). An age-specifier produces an absolute time value relative to the present time, and is most likely to be useful in retrieving historical events through evmget or the event viewer. It is not meaningful to use an age-specifier when setting a filter for use by the EVM logger or evmwatch.

If a period of weeks is specified, the period is converted to days by multiplying it by 7. When calculating an absolute time for an age specified in weeks or days, the first day is always regarded as the period from the previous midnight until the present time, and earlier days are counted from midnight to midnight. For example, if an age-specifier of 1d is given, events are selected relative to 12:00 a.m. on the same day. A value of 2d would select events relative to 12:00 a.m. the previous day. A value of 0d is valid, and is equivalent to 1d. See the following examples for more information.

If a period of hours, minutes or seconds is specified, an absolute time is calculated by subtracting the age from the current time, without regard to day boundaries. For example, if an age-specifier of 24h is given at 15:23:14, events are selected relative to 15:23:14 on the previous day.

A time-range-specifier consists of seven colon-separated fields in the following format:

year:month-of-year:day-of-month:day-of-week:hours:minutes:seconds 

Any component in the time range may be replaced by an asterisk (*) character as a wildcard, meaning that any value in this component will match the filter. You can specify multiple discrete values for a component by separating them with a comma. You can specify a range by using a hyphen to separate the starting and ending values for the range. An absolute-time-specifier is very similar to the time-range-specifier. It has only six components, and does not allow the use of wild cards. It has the following format:

year:month-of-year:day-of-month:hours:minutes:seconds 

In both forms of time specification, the range of values for each component is shown in the following table.

Specifier	Range
year	1970 to 2030
month-of-year	1 to 12
day-of-month	1 to 31
day-of-week	0 (Sun) to 6
hours	0 to 23
minutes	0 to 59
seconds	0 to 59

Any expression may be inverted (logically negated) by the use of the NOT operator, the exclamation mark (!) or the keyword NOT.

A complex filter is composed of two or more simple filters, combined using the AND (& or keyword AND) and OR (| or keyword OR) logical operators. Component filter expressions may be grouped in parentheses (( and )) to set the precedence of test operations. The order of precedence of logical and grouping operators (highest to lowest) is:

     ( ) ! & | 

Event filters can be direct or indirect. A direct filter is a text string appearing at the point of filter specification. An indirect filter is contained in a file, and is referred to using the following syntax:

@filename:filtername 

See evmfilterfile(4) for more information about using indirect filters.

If an event being evaluated does not contain the item being compared in a filter expression, the expression always yields no match. For example, if the timestamp item is missing from the event and you include the before keyword in a filter string, that part of the filter will return no match.

Notes

Successive versions of EVM may evolve the filter syntax by adding new keywords or operators.

EXAMPLES

The following table shows a number of filter specifications, and the interpretation given to each.

Filter String	Interpretation
"[name *]"	Any named event.
"[name myco.*]"	All events with names that start with `myco`.
"![name myco.*]"	All events with names that do not start with `myco`.
"[name ?.?.?]"	Any event with a name that has at least three components.
"[name myco.myapp.*]"	Any event with a name that has the first two components `myco.myapp`.
"[name myco.myapp]"	Any event with a name that has the first two components `myco.myapp`. Identical in meaning to the previous filter string.
"[name sys.unix.syslog]"	Events which have `sys.unix.syslog` as the first three components of the name.
"[name myco.myapp.*.showme]"	Any event name that starts with the components `myco.myapp` and ends with `showme`, no matter how many components are included between.
"[age < 1d]"	Any event posted today.
"[age < 4w]"	Any event posted within the last 4 weeks.
"[age lt 30s]"	Any event posted within the last 30 seconds.
"[age gt 1d]"	Any event posted before today.
"[time 2000:6:1::::]"	Any event posted on June 1, 2000.
"[time 2000:6:1,3::::]"	Any event posted on June 1 or June 3, 2000.
"[time 2000:6:1-3::::]"	Any event posted between June 1 and June 3, 2000.
"[time 2000:6:1-3,5-7::::]"	Any event posted between June 1 and June 3, 2000, or between June 5 and June 7, 2000, inclusive.
"[time ::::00-02::]"	All events occurring between midnight and 2:59:59 a.m., inclusive.
"[since 2000:6:1:03:00:00]"	All events occurring after 3:00 a.m. on June 1, 2000.
"[before 2000:6:1:03:00:00]"	All events occurring before 3:00 a.m. on June 1, 2000.
"[prio > 500]"	All events with priority greater than 500

"[name myco.myapp] & [pri >= 500]": All events that have names starting with myco.myapp and priority at least 500.
"[name myco.myapp] | [pri >= 500]": All events that have names starting with myco.myapp or that have priority at least 500.
"[name sys.unix.evm] & [age < 2d]": All evm events occurring today or yesterday.
"[name sys.unix.evm] and [time 2000:6:1-3:*:*:*:*]": All evm events occurring on June 1, 2 or 3, 2000.
"none": Passes no events.
"0": Passes no events.
"all": Passes all events.
"1": Passes all events.
"@sys": Specifies an indirect filter. The filter string is the default filter contained in a filter file named sys or sys.evf.
"@sys:evm": Specifies an indirect filter. The filter string is the filter named evm contained in a filter file named sys or sys.evf.

EvmFilter(5)

Technical documentation

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NAME

DESCRIPTION

Notes

EXAMPLES

SEE ALSO

Commands

Routines

Files

Event Management

EVM Events