Expressions
Expressions are used for the filter, warning, critical and ok arguments.
Syntax
The basic syntax is <attribute> <operator> <value>. For a list and explanation
of allowed operators see the operator list.
The list of possible attributes is documented along with each check plugin.
ex.:
filter="status = 'started'"
critical="count >= 1"
Logical Operator
To combine multiple expressions you can use logical operator and brackets.
| Operator | Alias | Description | Example |
|---|---|---|---|
and | && | Logical and operator | count = 0 and state != 1 |
or | || | Logical or operator | used > 5 or free < 20 |
ex.:
filter="(status = 'started' or status = 'pending') and usage > 5%"
Operator
| Operator | Alias / Safe expression | Types | Case Sens. | Description |
|---|---|---|---|---|
= | ==, is, eq | Strings, Numbers | Yes | Matches on exact equality, ex.: status = 'started' |
!= | is not, ne | Strings, Numbers | Yes | Matches if value is not exactly equal. ex.: 5 != 3 |
like | ilike | Strings | No | Matches if value contains the condition (case insensitive substring match), ex.: status like "pend" |
unlike | not like, not ilike | Strings | No | Matches if value does not contain the case insensitive substring, ex.: status unlike "stopped" |
slike | strictlike | Strings | Yes | Matches a case sensitive substring, ex.: name slike "WMI" |
not slike | not strictlike | Strings | Yes | Matches if a case sensitive substring cannot be found, ex.: name not slike "WMI" |
~ | regex, regexp | Strings | Yes | Performs a regular expression match, ex.: status ~ '^pend' |
!~ | not regex, not regexp | Strings | Yes | Performs a inverse regular expression match, ex.: status !~ 'stop' |
~~ | regexi, regexpi | Strings | No | Performs a case insensitive regular expression match, ex.: status ~~ '^pend'. An alternative way is to use //i as in status ~ /^pend/i |
!~~ | not regexi, not regexpi | Strings | No | Performs a inverse case insensitive regular expression match, ex.: status !~~ 'stop' |
< | lt | Numbers | - | Matches lower than numbers, ex.: usage < 5% |
<= | le, lte | Numbers | - | Matches lower or equal numbers, ex.: usage <= 5% |
> | gt | Numbers | - | Matches greater than numbers, ex.: usage > 5% |
>= | ge, gte | Numbers | - | Matches greater or equal numbers, ex.: usage >= 5% |
in | Strings | Yes | Matches if element is in list ex.: status in ('start', 'pending') | |
not in | Strings | Yes | Matches if element is not in list ex.: status not in ('stopped', 'starting') |
Other Operators
For backwards compatibility there more operators available:
| Operator | Alias | Description | Example |
|---|---|---|---|
'' | str() | String constant | exe like str(winlogon.exe) |
Date Keywords
For attributes representing a date or timestamp, the following keywords can be used as values:
| Keyword | Description |
|---|---|
today | Start of the current day (00:00:00 local time) |
thisweek | Start of the current week (Monday 00:00:00 local time) |
thismonth | Start of the current month (1st, 00:00:00 local time) |
thisyear | Start of the current year (Jan 1st, 00:00:00 local time) |
Each keyword can be suffixed with :utc to use UTC time instead of local time, e.g., today:utc.