Splunk® Cloud Services

SPL2 Search Reference

rex command syntax details


The required syntax is in bold.

[field=<field>] [max_match=<int>] [offset_field=<string>]
( <regex-expression> | mode=sed <sed-expression> )

Required arguments

You must specify either <regex-expression> or mode=sed <sed-expression> when you use the rex command.

Syntax: <string>
Description: The regular expression using the perl-compatible regular expressions (PCRE) format that defines the information to match and extract from the specified field. Quotation marks are required.

The Edge Processor solution supports Regular Expression 2 (RE2) syntax instead of PCRE syntax. In particular RE2 and PCRE accept different syntax for named capture groups. See Regular expression syntax for Edge Processor pipelines in Use Edge Processors.

Syntax: mode=sed
Description: Specify to indicate that you are using a sed (UNIX stream editor) expression.
Syntax: <string>
Description: When mode=sed, specify whether to replace strings (s) or substitute characters (y) in the matching regular expression. No other sed commands are implemented. Quotation marks are required. Sed mode supports the following flags: global (g) and Nth occurrence (N), where N is a number that is the character location in the string.

Optional arguments

Syntax: field=<field>
Description: The field that you want to extract information from.
Default: _raw
Syntax: max_match=<int>
Description: Controls the number of times the regular expression is matched. If greater than 1, the resulting fields are multivalued fields. You can use 0 for unlimited matches.
Default: 1
Syntax: offset_field=<string>
Description: If provided, a field is created with the name specified by <string>. The value of this field has the endpoints of the match in terms of zero-offset characters into the matched field. For example, if the rex expression is (?<tenchars>.{10}), this matches the first ten characters of the field, and the offset_field contents is 0-9.
Default: None

See also

rex command
rex command overview
rex command usage
rex command examples
Last modified on 13 February, 2023
rex command overview   rex command usage

This documentation applies to the following versions of Splunk® Cloud Services: current

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