Regular Expressions 101

Community Patterns

22

Get path from any text

Created·2023-01-31 14:38
Updated·2023-07-23 20:17
Flavor·PCRE2 (PHP)
Recommended·
Get path (windows style) from any type of text (error message, e-mail corps ...), quoted or not. THIS IS THE SINGLE LINE VERSION ! If you want understand how it work or edit it, go https://regex101.com/r/7o2fyy Relative path are not supported The goal is to catch what "Look like" a path. See the limitations UNC path and prefix path like //./], [//?/] or [//./UNC/] are allowed some url path like [file:///C:/] or [file://] are allowed Catch path quoted with ["] and [']. But these quotes are include with the catch Quoted path is not concerned by limitations Limitations : (only unquoted path) [dot] and [space] is allowed, but not in a row [dot+space] or [space+dot at end of file name isn't catched INSIDE A NAME FILE (or last directory if it is a path to a directory) : [comma] is not supported (it stop the catch) after a first [dot], any [space] stop the catch after a [space], catch is stoped if next character is not a [letter], [digit] or [-] so, double [space] stop the catch Compatibility compatible PCRE, PCRE2 AutoHotkey : don't forget to escape "%" in "`%" /!\ Powershell and .Net /!\\ : this regex need some modification to be interpreted by powershell. You have to replace each (?&CapturGroupName) by \k. Use this powershell code to do this replacement : ` $powershellRegex = @' [Put here the regex to replace (?&CapturGroupName) with \k] '@ -replace '\(\?&(\w+)\)', '\k' ` This example code must return : [Put here the regex to replace \k with \k]
Submitted by nitrateag

Community Library Entry

2

Regular Expression
Created·2026-01-21 16:32
Updated·2026-01-21 16:36
Flavor·JavaScript

/
^[A-Za-z0-9][A-Za-z0-9_+&*-]*(?:\.[A-Za-z0-9_+&*-]+)*@(?:[A-Za-z0-9](?:[A-Za-z0-9-]{0,61}[A-Za-z0-9])?\.)+[A-Za-z]{2,63}$
/
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Description

This regular expression provides a balance between RFC compliance and security-best-practices. It is designed to prevent injection vectors in legacy systems by using a restricted "safe" character subset recommended by the OWASP Validation Regex Repository.

Pattern:

^[A-Za-z0-9][A-Za-z0-9_+&*-]*(?:\.[A-Za-z0-9_+&*-]+)*@(?:[A-Za-z0-9](?:[A-Za-z0-9-]{0,61}[A-Za-z0-9])?\.)+[A-Za-z]{2,63}$

Key Features:

  • Forced Alphanumeric Start: Prevents leading hyphens to avoid command injection vulnerabilities.
  • Security Subset: Restricts special characters to _+&*- to prevent exotic character injections (e.g., pipes or backticks).
  • No Quoted Strings: Forbids quoted strings to eliminate dangerous payloads containing spaces or backslashes.
  • DNS Compliance: Enforces label lengths (1–63 characters) and prevents labels from starting or ending with hyphens.
  • Whole String Anchoring: Uses ^ and $ to ensure the entire input is validated.
Submitted by Gor Sargsyan