OpenSearch/docs/reference/eql/functions.asciidoc

279 lines
6.5 KiB
Plaintext

[[eql-function-ref]]
== EQL function reference
++++
<titleabbrev>Function reference</titleabbrev>
++++
experimental::[]
{es} supports the following EQL functions:
* <<eql-fn-endswith>>
* <<eql-fn-length>>
* <<eql-fn-startswith>>
* <<eql-fn-substring>>
[discrete]
[[eql-fn-endswith]]
=== `endsWith`
Returns `true` if a source string ends with a provided substring. Matching is
case insensitive.
[%collapsible]
====
*Example*
[source,eql]
----
endsWith("regsvr32.exe", ".exe") // returns true
endsWith("regsvr32.exe", ".EXE") // returns true
endsWith("regsvr32.exe", ".dll") // returns false
endsWith("", "") // returns true
// file.name = "regsvr32.exe"
endsWith(file.name, ".exe") // returns true
endsWith(file.name, ".dll") // returns false
// file.extension = ".exe"
endsWith("regsvr32.exe", file.extension) // returns true
endsWith("ntdll.dll", file.name) // returns false
// file.name = [ "ntdll.dll", "regsvr32.exe" ]
endsWith(file.name, ".dll") // returns true
endsWith(file.name, ".exe") // returns false
// null handling
endsWith("regsvr32.exe", null) // returns null
endsWith("", null) // returns null
endsWith(null, ".exe") // returns null
endsWith(null, null) // returns null
----
*Syntax*
[source,txt]
----
endsWith(<source>, <substring>)
----
*Parameters*
`<source>`::
+
--
(Required, string or `null`)
Source string. If `null`, the function returns `null`.
If using a field as the argument, this parameter only supports the following
field datatypes:
* <<keyword,`keyword`>>
* <<constant-keyword,`constant_keyword`>>
* <<text,`text`>> field with a <<keyword,`keyword`>> or
<<constant-keyword,`constant_keyword`>> sub-field
Fields containing <<array,array values>> use the first array item only.
--
`<substring>`::
+
--
(Required, string or `null`)
Substring to search for. If `null`, the function returns `null`.
If using a field as the argument, this parameter only supports the following
field datatypes:
* <<keyword,`keyword`>>
* <<constant-keyword,`constant_keyword`>>
* <<text,`text`>> field with a <<keyword,`keyword`>> or
<<constant-keyword,`constant_keyword`>> sub-field
--
*Returns:* boolean or `null`
====
[discrete]
[[eql-fn-length]]
=== `length`
Returns the character length of a provided string, including whitespace and
punctuation.
[%collapsible]
====
*Example*
[source,eql]
----
length("explorer.exe") // returns 12
length("start explorer.exe") // returns 18
length("") // returns 0
length(null) // returns null
// process.name = "regsvr32.exe"
length(process.name) // returns 12
----
*Syntax*
[source,txt]
----
length(<string>)
----
*Parameters*
`<string>`::
+
--
(Required, string or `null`)
String for which to return the character length. If `null`, the function returns
`null`. Empty strings return `0`.
If using a field as the argument, this parameter only supports the following
field datatypes:
* <<keyword,`keyword`>>
* <<constant-keyword,`constant_keyword`>>
* <<text,`text`>> field with a <<keyword,`keyword`>> or
<<constant-keyword,`constant_keyword`>> sub-field
<<array,Array values>> are not supported.
--
*Returns:* integer or `null`
====
[discrete]
[[eql-fn-startswith]]
=== `startsWith`
Returns `true` if a source string begins with a provided substring. Matching is
case insensitive.
[%collapsible]
====
*Example*
[source,eql]
----
startsWith("regsvr32.exe", "regsvr32") // returns true
startsWith("regsvr32.exe", "RegSvr32") // returns true
startsWith("regsvr32.exe", "explorer") // returns false
startsWith("", "") // returns true
// process.name = "regsvr32.exe"
startsWith(process.name, "regsvr32") // returns true
startsWith(process.name, "explorer") // returns false
// process.name = "regsvr32"
startsWith("regsvr32.exe", process.name) // returns true
startsWith("explorer.exe", process.name) // returns false
// process.name = [ "explorer.exe", "regsvr32.exe" ]
startsWith(process.name, "explorer") // returns true
startsWith(process.name, "regsvr32") // returns false
// null handling
startsWith("regsvr32.exe", null) // returns null
startsWith("", null) // returns null
startsWith(null, "regsvr32") // returns null
startsWith(null, null) // returns null
----
*Syntax*
[source,txt]
----
startsWith(<source>, <substring>)
----
*Parameters*
`<source>`::
+
--
(Required, string or `null`)
Source string. If `null`, the function returns `null`.
If using a field as the argument, this parameter only supports the following
field datatypes:
* <<keyword,`keyword`>>
* <<constant-keyword,`constant_keyword`>>
* <<text,`text`>> field with a <<keyword,`keyword`>> or
<<constant-keyword,`constant_keyword`>> sub-field
Fields containing <<array,array values>> use the first array item only.
--
`<substring>`::
+
--
(Required, string or `null`)
Substring to search for. If `null`, the function returns `null`.
If using a field as the argument, this parameter only supports the following
field datatypes:
* <<keyword,`keyword`>>
* <<constant-keyword,`constant_keyword`>>
* <<text,`text`>> field with a <<keyword,`keyword`>> or
<<constant-keyword,`constant_keyword`>> sub-field
--
*Returns:* boolean or `null`
====
[discrete]
[[eql-fn-substring]]
=== `substring`
Extracts a substring from a source string at provided start and end positions.
If no end position is provided, the function extracts the remaining string.
[%collapsible]
====
*Example*
[source,eql]
----
substring("start regsvr32.exe", 6) // returns "regsvr32.exe"
substring("start regsvr32.exe", 0, 5) // returns "start"
substring("start regsvr32.exe", 6, 14) // returns "regsvr32"
substring("start regsvr32.exe", -4) // returns ".exe"
substring("start regsvr32.exe", -4, -1) // returns ".ex"
----
*Syntax*
[source,txt]
----
substring(<source>, <start_pos>[, <end_pos>])
----
*Parameters*
`<source>`::
(Required, string)
Source string.
`<start_pos>`::
+
--
(Required, integer)
Starting position for extraction.
If this position is higher than the `<end_pos>` position or the length of the
`<source>` string, the function returns an empty string.
Positions are zero-indexed. Negative offsets are supported.
--
`<end_pos>`::
(Optional, integer)
Exclusive end position for extraction. If this position is not provided, the
function returns the remaining string.
+
Positions are zero-indexed. Negative offsets are supported.
*Returns:* string
====