OpenSearch/docs/reference/eql/functions.asciidoc

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[role="xpack"]
[testenv="basic"]
[[eql-function-ref]]
== EQL function reference
++++
<titleabbrev>Function reference</titleabbrev>
++++
dev::[]
{es} supports the following EQL functions:
* <<eql-fn-add>>
* <<eql-fn-between>>
* <<eql-fn-cidrmatch>>
* <<eql-fn-concat>>
* <<eql-fn-divide>>
* <<eql-fn-endswith>>
* <<eql-fn-indexof>>
* <<eql-fn-length>>
* <<eql-fn-match>>
* <<eql-fn-modulo>>
* <<eql-fn-multiply>>
* <<eql-fn-number>>
* <<eql-fn-startswith>>
* <<eql-fn-string>>
* <<eql-fn-stringcontains>>
* <<eql-fn-substring>>
* <<eql-fn-subtract>>
* <<eql-fn-wildcard>>
[discrete]
[[eql-fn-add]]
=== `add`
Returns the sum of two provided addends.
[%collapsible]
====
*Example*
[source,eql]
----
add(4, 5) // returns 9
add(4, 0.5) // returns 4.5
add(0.5, 0.25) // returns 0.75
add(4, -2) // returns 2
add(-2, -2) // returns -4
// process.args_count = 4
add(process.args_count, 5) // returns 9
add(process.args_count, 0.5) // returns 4.5
// process.parent.args_count = 2
add(process.args_count, process.parent.args_count) // returns 6
// null handling
add(null, 4) // returns null
add(4. null) // returns null
add(null, process.args_count) // returns null
add(process.args_count null) // returns null
----
*Syntax*
[source,txt]
----
add(<addend>, <addend>)
----
*Parameters:*
`<addend>`::
(Required, integer or float or `null`)
Addend to add. If `null`, the function returns `null`.
+
Two addends are required. No more than two addends can be provided.
+
If using a field as the argument, this parameter supports only
<<number,`numeric`>> field data types.
*Returns:* integer, float, or `null`
====
[discrete]
[[eql-fn-between]]
=== `between`
Extracts a substring that's between a provided `left` and `right` text in a
source string.
[%collapsible]
====
*Example*
[source,eql]
----
// file.path = "C:\\Windows\\System32\\cmd.exe"
between(file.path, "system32\\\\", ".exe") // returns "cmd"
between(file.path, "workspace\\\\", ".exe") // returns ""
// Greedy matching defaults to false.
between(file.path, "\\\\", "\\\\", false) // returns "Windows"
// Sets greedy matching to true
between(file.path, "\\\\", "\\\\", true) // returns "Windows\\System32"
// Case sensitivity defaults to false.
between(file.path, "system32\\\\", ".exe", false, false) // returns "cmd"
// Sets case sensitivity to true
between(file.path, "system32\\\\", ".exe", false, true) // returns ""
between(file.path, "System32\\\\", ".exe", false, true) // returns "cmd"
// empty source string
between("", "system32\\\\", ".exe") // returns ""
between("", "", "") // returns ""
// null handling
between(null, "system32\\\\", ".exe") // returns null
----
*Syntax*
[source,txt]
----
between(<source>, <left>, <right>[, <greedy_matching>, <case_sensitive>])
----
*Parameters*
`<source>`::
+
--
(Required, string or `null`)
Source string. Empty strings return an empty string (`""`), regardless of the
`<left>` or `<right>` parameters. If `null`, the function returns `null`.
If using a field as the argument, this parameter supports only the following
field data types:
* <<keyword,`keyword`>>
* <<constant-keyword,`constant_keyword`>>
* <<text,`text`>> field with a <<keyword,`keyword`>> or
<<constant-keyword,`constant_keyword`>> sub-field
--
`<left>`::
+
--
(Required, string)
Text to the left of the substring to extract. This text should include
whitespace.
If using a field as the argument, this parameter supports only the following
field data types:
* <<keyword,`keyword`>>
* <<constant-keyword,`constant_keyword`>>
* <<text,`text`>> field with a <<keyword,`keyword`>> or
<<constant-keyword,`constant_keyword`>> sub-field
--
`<right>`::
+
--
(Required, string)
Text to the right of the substring to extract. This text should include
whitespace.
If using a field as the argument, this parameter supports only the following
field data types:
* <<keyword,`keyword`>>
* <<constant-keyword,`constant_keyword`>>
* <<text,`text`>> field with a <<keyword,`keyword`>> or
<<constant-keyword,`constant_keyword`>> sub-field
--
`<greedy_matching>`::
(Optional, boolean)
If `true`, match the longest possible substring, similar to `.*` in regular
expressions. If `false`, match the shortest possible substring, similar to `.*?`
in regular expressions. Defaults to `false`.
`<case_sensitive>`::
(Optional, boolean)
If `true`, matching is case-sensitive. Defaults to `false`.
*Returns:* string or `null`
====
[discrete]
[[eql-fn-cidrmatch]]
=== `cidrMatch`
Returns `true` if an IP address is contained in one or more provided
https://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing[CIDR] blocks.
[%collapsible]
====
*Example*
[source,eql]
----
// source.address = "192.168.152.12"
cidrMatch(source.address, "192.168.0.0/16") // returns true
cidrMatch(source.address, "192.168.0.0/16", "10.0.0.0/8") // returns true
cidrMatch(source.address, "10.0.0.0/8") // returns false
cidrMatch(source.address, "10.0.0.0/8", "10.128.0.0/9") // returns false
// null handling
cidrMatch(null, "10.0.0.0/8") // returns null
cidrMatch(source.address, null) // returns null
----
*Syntax*
[source,txt]
----
`cidrMatch(<ip_address>, <cidr_block>[, ...])`
----
*Parameters*
`<ip_address>`::
(Required, string or `null`)
IP address. Supports
https://en.wikipedia.org/wiki/IPv4[IPv4] and
https://en.wikipedia.org/wiki/IPv6[IPv6] addresses. If `null`, the function
returns `null`.
+
If using a field as the argument, this parameter supports only the <<ip,`ip`>>
field data type.
`<cidr_block>`::
(Required{multi-arg}, string or `null`)
CIDR block you wish to search. If `null`, the function returns `null`.
*Returns:* boolean or `null`
====
[discrete]
[[eql-fn-concat]]
=== `concat`
Returns a concatenated string of provided values.
[%collapsible]
====
*Example*
[source,eql]
----
concat("process is ", "regsvr32.exe") // returns "process is regsvr32.exe"
concat("regsvr32.exe", " ", 42) // returns "regsvr32.exe 42"
concat("regsvr32.exe", " ", 42.5) // returns "regsvr32.exe 42.5"
concat("regsvr32.exe", " ", true) // returns "regsvr32.exe true"
concat("regsvr32.exe") // returns "regsvr32.exe"
// process.name = "regsvr32.exe"
concat(process.name, " ", 42) // returns "regsvr32.exe 42"
concat(process.name, " ", 42.5) // returns "regsvr32.exe 42.5"
concat("process is ", process.name) // returns "process is regsvr32.exe"
concat(process.name, " ", true) // returns "regsvr32.exe true"
concat(process.name) // returns "regsvr32.exe"
// process.arg_count = 4
concat(process.name, " ", process.arg_count) // returns "regsvr32.exe 4"
// null handling
concat(null, "regsvr32.exe") // returns null
concat(process.name, null) // returns null
concat(null) // returns null
----
*Syntax*
[source,txt]
----
concat(<value>[, <value>])
----
*Parameters*
`<value>`::
(Required{multi-arg-ref})
Value to concatenate. If any of the arguments are `null`, the function returns `null`.
+
If using a field as the argument, this parameter does not support the
<<text,`text`>> field data type.
*Returns:* string or `null`
====
[discrete]
[[eql-fn-divide]]
==== `divide`
Returns the quotient of a provided dividend and divisor.
[%collapsible]
====
[[eql-divide-fn-float-rounding]]
[WARNING]
=====
If both the dividend and divisor are integers, the `divide` function _rounds
down_ any returned floating point numbers to the nearest integer.
EQL queries in {es} should account for this rounding. To avoid rounding, convert
either the dividend or divisor to a float.
[%collapsible]
.**Example**
======
The `process.args_count` field is a <<number,`long`>> integer field containing a
count of process arguments.
A user might expect the following EQL query to only match events with a
`process.args_count` value of `4`.
[source,eql]
----
process where divide(4, process.args_count) == 1
----
However, the EQL query matches events with a `process.args_count` value of `3`
or `4`.
For events with a `process.args_count` value of `3`, the `divide` function
returns a floating point number of `1.333...`, which is rounded down to `1`.
To match only events with a `process.args_count` value of `4`, convert
either the dividend or divisor to a float.
The following EQL query changes the integer `4` to the equivalent float `4.0`.
[source,eql]
----
process where divide(4.0, process.args_count) == 1
----
======
=====
*Example*
[source,eql]
----
divide(4, 2) // returns 2
divide(4, 3) // returns 1
divide(4, 3.0) // returns 1.333...
divide(4, 0.5) // returns 8
divide(0.5, 4) // returns 0.125
divide(0.5, 0.25) // returns 2.0
divide(4, -2) // returns -2
divide(-4, -2) // returns 2
// process.args_count = 4
divide(process.args_count, 2) // returns 2
divide(process.args_count, 3) // returns 1
divide(process.args_count, 3.0) // returns 1.333...
divide(12, process.args_count) // returns 3
divide(process.args_count, 0.5) // returns 8
divide(0.5, process.args_count) // returns 0.125
// process.parent.args_count = 2
divide(process.args_count, process.parent.args_count) // returns 2
// null handling
divide(null, 4) // returns null
divide(4, null) // returns null
divide(null, process.args_count) // returns null
divide(process.args_count, null) // returns null
----
*Syntax*
[source,txt]
----
divide(<dividend>, <divisor>)
----
*Parameters*
`<dividend>`::
(Required, integer or float or `null`)
Dividend to divide. If `null`, the function returns `null`.
+
If using a field as the argument, this parameter supports only
<<number,`numeric`>> field data types.
`<divisor>`::
(Required, integer or float or `null`)
Divisor to divide by. If `null`, the function returns `null`. This value cannot
be zero (`0`).
+
If using a field as the argument, this parameter supports only
<<number,`numeric`>> field data types.
*Returns:* integer, float, or null
====
[discrete]
[[eql-fn-endswith]]
=== `endsWith`
Returns `true` if a source string ends with a provided substring.
[%collapsible]
====
*Example*
[source,eql]
----
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
// 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 supports only the following
field data types:
* <<keyword,`keyword`>>
* <<constant-keyword,`constant_keyword`>>
* <<text,`text`>> field with a <<keyword,`keyword`>> or
<<constant-keyword,`constant_keyword`>> sub-field
--
`<substring>`::
+
--
(Required, string or `null`)
Substring to search for. If `null`, the function returns `null`.
If using a field as the argument, this parameter supports only the following
field data types:
* <<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-indexof]]
=== `indexOf`
Returns the first position of a provided substring in a source string.
If an optional start position is provided, this function returns the first
occurrence of the substring at or after the start position.
[%collapsible]
====
*Example*
[source,eql]
----
// url.domain = "subdomain.example.com"
indexOf(url.domain, ".") // returns 9
indexOf(url.domain, ".", 9) // returns 9
indexOf(url.domain, ".", 10) // returns 17
indexOf(url.domain, ".", -6) // returns 9
// empty strings
indexOf("", "") // returns 0
indexOf(url.domain, "") // returns 0
indexOf(url.domain, "", 9) // returns 9
indexOf(url.domain, "", 10) // returns 10
indexOf(url.domain, "", -6) // returns 0
// missing substrings
indexOf(url.domain, "z") // returns null
indexOf(url.domain, "z", 9) // returns null
// start position is higher than string length
indexOf(url.domain, ".", 30) // returns null
// null handling
indexOf(null, ".", 9) // returns null
indexOf(url.domain, null, 9) // returns null
indexOf(url.domain, ".", null) // returns null
----
*Syntax*
[source,txt]
----
indexOf(<source>, <substring>[, <start_pos>])
----
*Parameters*
`<source>`::
+
--
(Required, string or `null`)
Source string. If `null`, the function returns `null`.
If using a field as the argument, this parameter supports only the following
field data types:
* <<keyword,`keyword`>>
* <<constant-keyword,`constant_keyword`>>
* <<text,`text`>> field with a <<keyword,`keyword`>> or
<<constant-keyword,`constant_keyword`>> sub-field
--
`<substring>`::
+
--
(Required, string or `null`)
Substring to search for.
If this argument is `null` or the `<source>` string does not contain this
substring, the function returns `null`.
If the `<start_pos>` is positive, empty strings (`""`) return the `<start_pos>`.
Otherwise, empty strings return `0`.
If using a field as the argument, this parameter supports only the following
field data types:
* <<keyword,`keyword`>>
* <<constant-keyword,`constant_keyword`>>
* <<text,`text`>> field with a <<keyword,`keyword`>> or
<<constant-keyword,`constant_keyword`>> sub-field
--
`<start_pos>`::
+
--
(Optional, integer or `null`)
Starting position for matching. The function will not return positions before
this one. Defaults to `0`.
Positions are zero-indexed. Negative offsets are treated as `0`.
If this argument is `null` or higher than the length of the `<source>` string,
the function returns `null`.
If using a field as the argument, this parameter supports only the following
<<number,numeric>> field data types:
* `long`
* `integer`
* `short`
* `byte`
--
*Returns:* integer 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 supports only the following
field data types:
* <<keyword,`keyword`>>
* <<constant-keyword,`constant_keyword`>>
* <<text,`text`>> field with a <<keyword,`keyword`>> or
<<constant-keyword,`constant_keyword`>> sub-field
--
*Returns:* integer or `null`
====
[discrete]
[[eql-fn-match]]
=== `match`
Returns `true` if a source string matches one or more provided regular
expressions.
[%collapsible]
====
*Example*
[source,eql]
----
match("explorer.exe", "[a-z]*?.exe") // returns true
match("explorer.exe", "[a-z]*?.exe", "[1-9]") // returns true
match("explorer.exe", "[1-9]") // returns false
match("explorer.exe", "") // returns false
// process.name = "explorer.exe"
match(process.name, "[a-z]*?.exe") // returns true
match(process.name, "[a-z]*?.exe", "[1-9]") // returns true
match(process.name, "[1-9]") // returns false
match(process.name, "") // returns false
// null handling
match(null, "[a-z]*?.exe") // returns null
----
*Syntax*
[source,txt]
----
match(<source>, <reg_exp>[, ...])
----
*Parameters*
`<source>`::
+
--
(Required, string or `null`)
Source string. If `null`, the function returns `null`.
If using a field as the argument, this parameter supports only the following
field data types:
* <<keyword,`keyword`>>
* <<constant-keyword,`constant_keyword`>>
* <<text,`text`>> field with a <<keyword,`keyword`>> or
<<constant-keyword,`constant_keyword`>> sub-field
--
`<reg_exp>`::
+
--
(Required{multi-arg-ref}, string)
Regular expression used to match the source string. For supported syntax, see
<<regexp-syntax>>.
https://docs.oracle.com/javase/tutorial/essential/regex/pre_char_classes.html[Predefined
character classes] are not supported.
Fields are not supported as arguments.
--
*Returns:* boolean or `null`
====
[discrete]
[[eql-fn-modulo]]
=== `modulo`
Returns the remainder of the division of a provided dividend and divisor.
[%collapsible]
====
*Example*
[source,eql]
----
modulo(10, 6) // returns 4
modulo(10, 5) // returns 0
modulo(10, 0.5) // returns 0
modulo(10, -6) // returns 4
modulo(-10, -6) // returns -4
// process.args_count = 10
modulo(process.args_count, 6) // returns 4
modulo(process.args_count, 5) // returns 0
modulo(106, process.args_count) // returns 6
modulo(process.args_count, -6) // returns 4
modulo(process.args_count, 0.5) // returns 0
// process.parent.args_count = 6
add(process.args_count, process.parent.args_count) // returns 4
// null handling
modulo(null, 5) // returns null
modulo(7, null) // returns null
modulo(null, process.args_count) // returns null
modulo(process.args_count, null) // returns null
----
*Syntax*
[source,txt]
----
modulo(<dividend>, <divisor>)
----
*Parameters*
`<dividend>`::
(Required, integer or float or `null`)
Dividend to divide. If `null`, the function returns `null`. Floating point
numbers return `0`.
+
If using a field as the argument, this parameter supports only
<<number,`numeric`>> field data types.
`<divisor>`::
(Required, integer or float or `null`)
Divisor to divide by. If `null`, the function returns `null`. Floating point
numbers return `0`. This value cannot be zero (`0`).
+
If using a field as the argument, this parameter supports only
<<number,`numeric`>> field data types.
*Returns:* integer, float, or `null`
====
[discrete]
[[eql-fn-multiply]]
=== `multiply`
Returns the product of two provided factors.
[%collapsible]
====
*Example*
[source,eql]
----
multiply(2, 2) // returns 4
multiply(0.5, 2) // returns 1
multiply(0.25, 2) // returns 0.5
multiply(-2, 2) // returns -4
multiply(-2, -2) // returns 4
// process.args_count = 2
multiply(process.args_count, 2) // returns 4
multiply(0.5, process.args_count) // returns 1
multiply(0.25, process.args_count) // returns 0.5
// process.parent.args_count = 3
multiply(process.args_count, process.parent.args_count) // returns 6
// null handling
multiply(null, 2) // returns null
multiply(2, null) // returns null
----
*Syntax*
[source,txt]
----
multiply(<factor, <factor>)
----
*Parameters*
`<factor>`::
+
--
(Required, integer or float or `null`)
Factor to multiply. If `null`, the function returns `null`.
Two factors are required. No more than two factors can be provided.
If using a field as the argument, this parameter supports only
<<number,`numeric`>> field data types.
--
*Returns:* integer, float, or `null`
====
[discrete]
[[eql-fn-number]]
=== `number`
Converts a string to the corresponding integer or float.
[%collapsible]
====
*Example*
[source,eql]
----
number("1337") // returns 1337
number("42.5") // returns 42.5
number("deadbeef", 16) // returns 3735928559
// integer literals beginning with "0x" are auto-detected as hexadecimal
number("0xdeadbeef") // returns 3735928559
number("0xdeadbeef", 16) // returns 3735928559
// "+" and "-" are supported
number("+1337") // returns 1337
number("-1337") // returns -1337
// surrounding whitespace is ignored
number(" 1337 ") // returns 1337
// process.pid = "1337"
number(process.pid) // returns 1337
// null handling
number(null) // returns null
number(null, 16) // returns null
// strings beginning with "0x" are treated as hexadecimal (base 16),
// even if the <base_num> is explicitly null.
number("0xdeadbeef", null) // returns 3735928559
// otherwise, strings are treated as decimal (base 10)
// if the <base_num> is explicitly null.
number("1337", null) // returns 1337
----
*Syntax*
[source,txt]
----
number(<string>[, <base_num>])
----
*Parameters*
`<string>`::
+
--
(Required, string or `null`)
String to convert to an integer or float. If this value is a string, it must be
one of the following:
* A string representation of an integer (e.g., `"42"`)
* A string representation of a float (e.g., `"9.5"`)
* If the `<base_num>` parameter is specified, a string containing an integer
literal in the base notation (e.g., `"0xDECAFBAD"` in hexadecimal or base
`16`)
Strings that begin with `0x` are auto-detected as hexadecimal and use a default
`<base_num>` of `16`.
`-` and `+` are supported with no space between. Surrounding whitespace is
ignored. Empty strings (`""`) are not supported.
If using a field as the argument, this parameter supports only the following
field data types:
* <<keyword,`keyword`>>
* <<constant-keyword,`constant_keyword`>>
* <<text,`text`>> field with a <<keyword,`keyword`>> or
<<constant-keyword,`constant_keyword`>> sub-field
If this argument is `null`, the function returns `null`.
--
`<base_num>`::
+
--
(Optional, integer or `null`)
Radix or base used to convert the string. If the `<string>` begins with `0x`,
this parameter defaults to `16` (hexadecimal). Otherwise, it defaults to base
`10`.
If this argument is explicitly `null`, the default value is used.
Fields are not supported as arguments.
--
*Returns:* integer or float or `null`
====
[discrete]
[[eql-fn-startswith]]
=== `startsWith`
Returns `true` if a source string begins with a provided substring.
[%collapsible]
====
*Example*
[source,eql]
----
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
// 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 supports only the following
field data types:
* <<keyword,`keyword`>>
* <<constant-keyword,`constant_keyword`>>
* <<text,`text`>> field with a <<keyword,`keyword`>> or
<<constant-keyword,`constant_keyword`>> sub-field
--
`<substring>`::
+
--
(Required, string or `null`)
Substring to search for. If `null`, the function returns `null`.
If using a field as the argument, this parameter supports only the following
field data types:
* <<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-string]]
=== `string`
Converts a value to a string.
[%collapsible]
====
*Example*
[source,eql]
----
string(42) // returns "42"
string(42.5) // returns "42.5"
string("regsvr32.exe") // returns "regsvr32.exe"
string(true) // returns "true"
// null handling
string(null) // returns null
----
*Syntax*
[source,txt]
----
string(<value>)
----
*Parameters*
`<value>`::
(Required)
Value to convert to a string. If `null`, the function returns `null`.
+
If using a field as the argument, this parameter does not support the
<<text,`text`>> field data type.
*Returns:* string or `null`
====
[discrete]
[[eql-fn-stringcontains]]
=== `stringContains`
Returns `true` if a source string contains a provided substring.
[%collapsible]
====
*Example*
[source,eql]
----
// process.command_line = "start regsvr32.exe"
stringContains(process.command_line, "regsvr32") // returns true
stringContains(process.command_line, "start ") // returns true
stringContains(process.command_line, "explorer") // returns false
// process.name = "regsvr32.exe"
stringContains(command_line, process.name) // returns true
// empty strings
stringContains("", "") // returns false
stringContains(process.command_line, "") // returns false
// null handling
stringContains(null, "regsvr32") // returns null
stringContains(process.command_line, null) // returns null
----
*Syntax*
[source,txt]
----
stringContains(<source>, <substring>)
----
*Parameters*
`<source>`::
(Required, string or `null`)
Source string to search. If `null`, the function returns `null`.
If using a field as the argument, this parameter supports only the following
field data types:
* <<keyword,`keyword`>>
* <<constant-keyword,`constant_keyword`>>
* <<text,`text`>> field with a <<keyword,`keyword`>> or
<<constant-keyword,`constant_keyword`>> sub-field
`<substring>`::
(Required, string or `null`)
Substring to search for. If `null`, the function returns `null`.
If using a field as the argument, this parameter supports only the following
field data types:
* <<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
====
[discrete]
[[eql-fn-subtract]]
=== `subtract`
Returns the difference between a provided minuend and subtrahend.
[%collapsible]
====
*Example*
[source,eql]
----
subtract(10, 2) // returns 8
subtract(10.5, 0.5) // returns 10
subtract(1, 0.2) // returns 0.8
subtract(-2, 4) // returns -8
subtract(-2, -4) // returns 8
// process.args_count = 10
subtract(process.args_count, 6) // returns 4
subtract(process.args_count, 5) // returns 5
subtract(15, process.args_count) // returns 5
subtract(process.args_count, 0.5) // returns 9.5
// process.parent.args_count = 6
subtract(process.args_count, process.parent.args_count) // returns 4
// null handling
subtract(null, 2) // returns null
subtract(2, null) // returns null
----
*Syntax*
[source,txt]
----
subtract(<minuend>, <subtrahend>)
----
*Parameters*
`<minuend>`::
(Required, integer or float or `null`)
Minuend to subtract from.
+
If using a field as the argument, this parameter supports only
<<number,`numeric`>> field data types.
`<subtrahend>`::
(Optional, integer or float or `null`)
Subtrahend to subtract. If `null`, the function returns `null`.
+
If using a field as the argument, this parameter supports only
<<number,`numeric`>> field data types.
*Returns:* integer, float, or `null`
====
[discrete]
[[eql-fn-wildcard]]
=== `wildcard`
Returns `true` if a source string matches one or more provided wildcard
expressions.
[%collapsible]
====
*Example*
[source,eql]
----
// The two following expressions are equivalent.
process.name == "*regsvr32*" or process.name == "*explorer*"
wildcard(process.name, "*regsvr32*", "*explorer*")
// process.name = "regsvr32.exe"
wildcard(process.name, "*regsvr32*") // returns true
wildcard(process.name, "*regsvr32*", "*explorer*") // returns true
wildcard(process.name, "*explorer*") // returns false
wildcard(process.name, "*explorer*", "*scrobj*") // returns false
// empty strings
wildcard("", "*start*") // returns false
wildcard("", "*") // returns true
wildcard("", "") // returns true
// null handling
wildcard(null, "*regsvr32*") // returns null
wildcard(process.name, null) // returns null
----
*Syntax*
[source,txt]
----
wildcard(<source>, <wildcard_exp>[, ...])
----
*Parameters*
`<source>`::
+
--
(Required, string)
Source string. If `null`, the function returns `null`.
If using a field as the argument, this parameter supports only the following
field data types:
* <<keyword,`keyword`>>
* <<constant-keyword,`constant_keyword`>>
* <<text,`text`>> field with a <<keyword,`keyword`>> or
<<constant-keyword,`constant_keyword`>> sub-field
--
`<wildcard_exp>`::
+
--
(Required{multi-arg-ref}, string)
Wildcard expression used to match the source string. If `null`, the function
returns `null`. Fields are not supported as arguments.
--
*Returns:* boolean
====