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regex
Description
Removes results that do not match the specified regular expression.
Syntax
The required syntax is in bold.
- regex
- (<field>=<regex-expression> | <field>!=<regex-expression> | <regex-expression>)
Required arguments
- <regex-expression>
- Syntax: "<string>"
- Description: An unanchored regular expression. The regular expression must be a Perl Compatible Regular Expression supported by the PCRE library. Quotation marks are required.
Optional arguments
- <field>
- Syntax: <field>
- Description: Specify the field name from which to match the values against the regular expression.
- You can specify that the
regexcommand keeps results that match the expression by using <field>=<regex-expression>. To keep results that do not match, specify <field>!=<regex-expression>. - Default:
_raw
Usage
The regex command is a distributable streaming command. See Command types.
Use the regex command to remove results that do not match the specified regular expression.
Use the rex command to either extract fields using regular expression named groups, or replace or substitute characters in a field using sed expressions.
When you use regular expressions in searches, you need to be aware of how characters such as pipe ( | ) and backslash ( \ ) are handled. See SPL and regular expressions in the Search Manual.
For general information about regular expressions, see About Splunk regular expressions in the Knowledge Manager Manual.
Examples
Example 1: Keep only search results whose "_raw" field contains IP addresses in the non-routable class A (10.0.0.0/8). This example uses a negative lookbehind assertion at the beginning of the expression.
... | regex _raw="(?<!\d)10\.\d{1,3}\.\d{1,3}\.\d{1,3}(?!\d)"
Example 2: Keep only the results that match a valid email address. For example, buttercup@example.com.
...| regex email="^([a-z0-9_\.-]+)@([\da-z\.-]+)\.([a-z\.]{2,6})$"
The following table explains each part of the expression.
| Part of the expression | Description |
|---|---|
^
|
Specifies the beginning of the string. |
([a-z0-9_\.-]+)
|
This is the first group in the expression. Specifies to match one or more lowercase letters, numbers, underscores, dots, or hyphens. The backslash ( \ ) character is used to escape the dot ( . ) character. The dot character is escaped, because a non-escaped dot matches any character. The plus ( + ) sign specifies to match from 1 to unlimited characters in this group. In this example this part of the expression matches buttercup in the email address buttercup@example.com. |
@
|
Matches the at symbol. |
([\da-z\.-]+)
|
This is the second group in the expression. Specifies to match the domain name, which can be one or more lowercase letters, numbers, underscores, dots, or hyphens. This is followed by another escaped dot character. The plus ( + ) sign specifies to match from 1 to unlimited characters in this group. In this example this part of the expression matches example in the email address buttercup@example.com. |
([a-z\.]{2,6})
|
This is the third group. Specifies to match the top-level domain (TLD), which can be 2 to 6 letters or dots. This group matches all types of TLDs, such as .co.uk, .edu, or .asia. In this example it matches .com in the email address buttercup@example.com.
|
$
|
Specifies the end of the string. |
See also
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This documentation applies to the following versions of Splunk® Enterprise: 6.3.0, 6.3.2, 6.3.3, 6.3.4, 6.3.5, 6.3.6, 6.3.7, 6.3.8, 6.3.9, 6.3.10, 6.3.11, 6.3.12, 6.3.13, 6.3.14, 6.4.0, 6.4.1, 6.4.2, 6.4.3, 6.4.4, 6.4.5, 6.4.6, 6.4.7, 6.4.8, 6.4.9, 6.4.10, 6.4.11, 6.5.0, 6.5.1, 6.5.2, 6.5.3, 6.5.4, 6.5.5, 6.5.6, 6.5.7, 6.5.8, 6.5.9, 6.5.10, 6.6.0, 6.6.1, 6.6.2, 6.6.3, 6.6.4, 6.6.5, 6.6.6, 6.6.7, 6.6.8, 6.6.9, 6.6.10, 6.6.11, 6.6.12, 7.0.0, 7.0.1, 7.0.2, 7.0.3, 7.0.5, 7.0.10, 7.0.11, 7.0.13, 6.3.1, 7.0.4, 7.0.9, 7.1.0, 7.1.1, 7.1.2, 7.1.3, 7.1.4, 7.1.5, 7.1.6, 7.1.7, 7.1.8, 7.1.9, 7.1.10, 7.2.0, 7.2.1, 7.2.2, 7.2.3, 7.2.4, 7.2.5, 7.2.6, 7.2.7, 7.2.8, 7.2.9, 7.2.10, 7.3.0, 7.3.1, 7.3.2, 7.3.3, 7.3.4, 7.3.5, 7.3.6, 7.3.7, 7.3.8, 7.3.9, 8.0.0, 8.0.1, 8.0.2, 8.0.3, 8.0.4, 8.0.5, 8.0.6, 8.0.7, 8.0.8, 8.0.9, 8.1.0, 8.1.1, 8.1.2, 8.1.3, 8.1.4, 8.1.5, 8.2.0, 8.2.1, 7.0.6, 7.0.7, 7.0.8
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