OpenSearch/docs/reference/eql/syntax.asciidoc

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[role="xpack"]
[testenv="basic"]
[[eql-syntax]]
== EQL syntax reference
experimental::[]
[IMPORTANT]
====
{es} supports a subset of EQL syntax.
====
[discrete]
[[eql-basic-syntax]]
=== Basic syntax
EQL queries require an event type and a matching condition. The `where` keyword connects them.
[source,eql]
----
event_type where condition
----
For example, the following EQL query matches `process` events with a `process.name`
field value of `svchost.exe`:
[source,eql]
----
process where process.name == "svchost.exe"
----
[discrete]
[[eql-syntax-conditions]]
==== Conditions
A condition consists of one or more criteria an event must match.
You can specify and combine these criteria using the following operators:
[discrete]
[[eql-syntax-comparison-operators]]
===== Comparison operators
[source,eql]
----
< <= == != >= >
----
.*Definitions*
[%collapsible]
====
`<` (less than)::
Returns `true` if the value to the left of the operator is less than the value
to the right. Otherwise returns `false`.
`<=` (less than or equal) ::
Returns `true` if the value to the left of the operator is less than or equal to
the value to the right. Otherwise returns `false`.
`==` (equal)::
Returns `true` if the values to the left and right of the operator are equal.
Otherwise returns `false`.
`!=` (not equal)::
Returns `true` if the values to the left and right of the operator are not
equal. Otherwise returns `false`.
`>=` (greater than or equal) ::
Returns `true` if the value to the left of the operator is greater than or equal
to the value to the right. Otherwise returns `false`.
`>` (greater than)::
Returns `true` if the value to the left of the operator is greater than the
value to the right. Otherwise returns `false`.
====
[discrete]
[[eql-syntax-logical-operators]]
===== Logical operators
[source,eql]
----
and or not
----
.*Definitions*
[%collapsible]
====
`and`::
Returns `true` only if the condition to the left and right _both_ return `true`.
Otherwise returns `false.
`or`::
Returns `true` if one of the conditions to the left or right `true`.
Otherwise returns `false.
`not`::
Returns `true` if the condition to the right is `false`.
====
[discrete]
[[eql-syntax-lookup-operators]]
===== Lookup operators
[source,eql]
----
user.name in ("Administrator", "SYSTEM", "NETWORK SERVICE")
user.name not in ("Administrator", "SYSTEM", "NETWORK SERVICE")
----
.*Definitions*
[%collapsible]
====
`in`::
Returns `true` if the value is contained in the provided list.
`not in`::
Returns `true` if the value is not contained in the provided list.
====
[discrete]
[[eql-syntax-math-operators]]
===== Math operators
[source,eql]
----
+ - * / %
----
.*Definitions*
[%collapsible]
====
`+` (add)::
Adds the values to the left and right of the operator.
`-` (Subtract)::
Subtracts the value to the right of the operator from the value to the left.
`*` (Subtract)::
Multiplies the values to the left and right of the operator.
`/` (Divide)::
Divides the value to the left of the operator by the value to the right.
`%` (modulo)::
Divides the value to the left of the operator by the value to the right. Returns only the remainder.
====
[discrete]
[[eql-syntax-strings]]
==== Strings
Strings are enclosed with double quotes (`"`) or single quotes (`'`).
[source,eql]
----
"hello world"
"hello world with 'substring'"
----
[discrete]
[[eql-syntax-wildcards]]
===== Wildcards
You can use the wildcard operator (`*`) within a string to match specific
patterns. You can use wildcards with the `==` (equal) or `!=` (not equal)
operators:
[source,eql]
----
field == "example*wildcard"
field != "example*wildcard"
----
[discrete]
[[eql-syntax-escaped-characters]]
===== Escaped characters
When used within a string, special characters, such as a carriage return or
double quote (`"`), must be escaped with a preceding backslash (`\`).
[source,eql]
----
"example \t of \n escaped \r characters"
----
.*Escape sequences*
[%collapsible]
====
[options="header"]
|====
| Escape sequence | Literal character
|`\n` | A newline (linefeed) character
|`\r` | A carriage return character
|`\t` | A tab character
|`\\` | A backslash (`\`) character
|`\"` | A double quote (`"`) character
|`\'` | A single quote (`'`) character
|====
====
[discrete]
[[eql-syntax-raw-strings]]
===== Raw strings
Raw strings are preceded by a question mark (`?`) and treat backslashes (`\`) as
literal characters.
[source,eql]
----
?"String with a literal 'blackslash' \ character included"
----
You can escape single quotes (`'`) and double quotes (`"`) with a backslash, but
the backslash remains in the resulting string.
[source,eql]
----
?"\""
----
[NOTE]
====
Raw strings cannot contain only a single backslash. Additionally, raw strings
cannot end in an odd number of backslashes.
====
[discrete]
[[eql-syntax-non-alpha-field-names]]
==== Non-alphanumeric field names
Field names containing non-alphanumeric characters, such as underscores (`_`),
dots (`.`), hyphens (`-`), or spaces, must be escaped using backticks (+++`+++).
[source,eql]
----
`my_field`
`my.field`
`my-field`
`my field`
----