# POSIX Regular Expressions

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---
title: POSIX Regular Expressions
latest-operator-version: v26.1.4
latest-console-tag: v3.7.3
latest-connect-version: 4.93.0
latest-redpanda-tag: v26.1.9
docname: sql/sql-functions/string-functions/regex/posix-regular-expressions
page-component-name: cloud-data-platform
page-version: master
page-component-version: master
page-component-title: Cloud
page-relative-src-path: sql/sql-functions/string-functions/regex/posix-regular-expressions.adoc
page-edit-url: https://github.com/redpanda-data/cloud-docs/edit/main/modules/reference/pages/sql/sql-functions/string-functions/regex/posix-regular-expressions.adoc
description: POSIX (Portable Operating System Interface) defines a set of standard operating system interfaces based on the UNIX OS.
page-topic-type: reference
page-git-created-date: "2026-05-26"
page-git-modified-date: "2026-05-26"
---

<!-- Source: https://docs.redpanda.com/cloud-data-platform/reference/sql/sql-functions/string-functions/regex/posix-regular-expressions.md -->

**POSIX** (Portable Operating System Interface) defines a set of standard operating system interfaces based on the UNIX OS. In POSIX Basic Regex Expression (BRE) syntax, most characters are treated as literals (for example, they match only themselves). However, some characters called **metacharacters** have special meaning.

This table describes common POSIX BRE metacharacters:

| Metacharacter | Description |
| --- | --- |
| . | Matches any single character. For example, a.c matches “abc”, but [a.c] matches only “a”, “.”, or “c” |
| - | Used to define a range. For example, [a-c] will match characters a to c (both inclusive) |
| [] | Matches a literal character |
| ^ | Matches the beginning of a line |
| $ | Matches the end of a line |
| * | Matches zero or more occurrences of the preceding element |
| {n} | Matches exactly n occurrences of the preceding element |
| \{n,m} | Matches between n and m occurrences of the preceding element |