Regex Tester

Test and debug regular expressions with real-time matching, group extraction, and common pattern library. Use when a user asks to test, debug, validate, or explain a regex pattern, or needs to extract data using regex from text.

Test and debug regular expressions with real-time matching and group extraction.

Usage

bash

python scripts/regex_tester.py --pattern "<regex>" [--text "<test string>"] [--flags i|m|s] [--list-patterns]

Arguments

Argument	Description
--pattern	Regex pattern to test (required)
--text	Test string to match against (default: reads from stdin)
--flags	Flags: i (ignore case), m (multiline), s (dotall)
--json	Output results as JSON
--list-patterns	Show common pattern library

Exit Codes

• 0 = match found
• 1 = no match
• 2 = invalid regex

Common Patterns

Pattern Name	Regex	Description
email	[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}	Email address
url	https?://[^\s]+	HTTP/HTTPS URL
ipv4	\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}	IPv4 address
uuid	[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}	UUID
phone	\+?[\d\s\-()]{10,}	Phone number
date-iso	\d{4}-\d{2}-\d{2}	ISO date (YYYY-MM-DD)
time-24h	`([01]?\d	2[0-3]):[0-5]\d`
hex-color	#[0-9a-fA-F]{3,8}	Hex color code
slug	[a-z0-9]+(?:-[a-z0-9]+)*	URL slug
credit-card	\d{4}[\s-]?\d{4}[\s-]?\d{4}[\s-]?\d{4}	Credit card number
hashtag	#[a-zA-Z0-9_]+	Hashtag
mention	@[a-zA-Z0-9_]+	@mention

Examples

bash

# Test a pattern interactively
python scripts/regex_tester.py --pattern "[a-z]+" --text "hello world"

# Use common pattern shorthand
python scripts/regex_tester.py --pattern "email" --text "[e-mail]"

# Case-insensitive match
python scripts/regex_tester.py --pattern "hello" --text "HELLO world" --flags i

# Extract all matches from file
python scripts/regex_tester.py --pattern "\d+" --text "order 123 and 456"

# JSON output for scripting
python scripts/regex_tester.py --pattern "\w+" --text "hello world" --json

Pattern Matching Output Format

text

Pattern: [a-z]+
Text:    "hello world"

Matches: 2 found
  [0] "hello" (pos 0-5)
  [1] "world" (pos 6-11)

Groups: none

For patterns with capture groups:

text

Pattern: (\w+)@(\w+)
Text:    "user@domain"

Matches: 1 found
  [0] "user@domain" (pos 0-11)
Groups:
  [1] "user"
  [2] "domain"