# RLIKE
<a name="RLIKE"></a>

The RLIKE operator allows you to check if a string matches a specified regular expression pattern.

Returns `true` if str matches `regexp`, or `false` otherwise.

## Syntax
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```
rlike(str, regexp)
```

## Arguments
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 *str*   
A string expression

 *regexp*   
A string expression. The regex string should be a Java regular expression.  
String literals (including regex patterns) are unescaped in our SQL parser. For example, to match "\$1abc", a regular expression for *regexp* can be "^\$1abc\$1".

## Examples
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The following example sets the value of the `spark.sql.parser.escapedStringLiterals` configuration parameter to `true`. This parameter is specific to the Spark SQL engine. The `spark.sql.parser.escapedStringLiterals` parameter in Spark SQL controls how the SQL parser handles escaped string literals. When set to `true`, the parser will interpret backslash characters (`\`) within string literals as escape characters, allowing you to include special characters like newlines, tabs, and quotation marks within your string values. 

```
SET spark.sql.parser.escapedStringLiterals=true;
spark.sql.parser.escapedStringLiterals  true
```

For example, with `spark.sql.parser.escapedStringLiterals=true`, you could use the following string literal in your SQL query:

```
SELECT 'Hello, world!\n'
```

The newline character `\n` would be interpreted as a literal newline character in the output. 

The following example performs a regular expression pattern match. The first argument is passed to the RLIKE operator. It's a string that represents a file path, where the actual username is replaced with the pattern '\$1\$1\$1\$1'. The second argument is the regular expression pattern used for the matching. The output (`true`) indicates that the first string (`'%SystemDrive%\Users\****'`) matches the regular expression pattern (`'%SystemDrive%\\Users.*'`).

```
SELECT rlike('%SystemDrive%\Users\John', '%SystemDrive%\Users.*');
true
```