Regexr

Regexr

Developer tools CLI for checking, validating, generating, and working with regular expressions and code patterns. Lint syntax, explain complex expressions, convert between formats, generate templates, diff pattern versions, preview matches, fix common regex issues, and produce reports — all from the command line with persistent local logging.

Commands

Run regexr [args] to use.

| Command | Description | |---------|-------------| | check | Check regex patterns for correctness and common pitfalls | | validate | Validate regex syntax and structure | | generate | Generate regex patterns from descriptions or examples | | format | Format and prettify regex expressions | | lint | Lint regex for style, performance, and safety issues | | explain | Explain what a regex pattern does in plain language | | convert | Convert regex between flavors (PCRE, JS, Python, etc.) | | template | Apply or manage regex templates for common use cases | | diff | Diff two regex patterns and show behavioral differences | | preview | Preview regex matches against sample text | | fix | Auto-fix common regex issues (escaping, anchoring, etc.) | | report | Generate regex quality and coverage reports | | stats | Show summary statistics across all categories | | export | Export data in json, csv, or txt format | | search | Search across all logged entries | | recent | Show recent activity from history log | | status | Health check — version, data dir, disk usage | | help | Show help and available commands | | version | Show version (v2.0.0) |

Each domain command (check, validate, generate, etc.) works in two modes:

Data Storage

All data is stored locally in ~/.local/share/regexr/:

Requirements

When to Use

1. Building and testing regex patterns — use generate to create patterns from descriptions, check to verify correctness, and preview to test against sample data 2. Learning and understanding regex — use explain to break down complex patterns into plain-language descriptions, perfect for code reviews or onboarding 3. Linting and fixing regex in codebases — run lint to catch performance and safety issues (catastrophic backtracking, unanchored patterns), then fix to auto-correct them 4. Converting regex across languages — use convert to translate patterns between JavaScript, Python, PCRE, and other flavors when porting code 5. Documenting regex usage in projects — log patterns with template, generate report summaries, and export data for documentation or audits

Examples

# Check a regex pattern for issues
regexr check "^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z]{2,}$ — email validation"
Validate regex syntax
regexr validate "(?<=@)[a-z]+\.com — lookbehind syntax OK"
Generate a pattern from description
regexr generate "match IPv4 addresses: \d{1,3}(\.\d{1,3}){3}"
Explain a complex regex
regexr explain "^(?=.*[A-Z])(?=.*\d).{8,}$ — password: 1 uppercase, 1 digit, 8+ chars"
Lint for performance issues
regexr lint "(a+)+ — warning: catastrophic backtracking possible"
Convert between flavors
regexr convert "JS→Python: /\d+/g becomes re.findall(r'\d+', text)"
Fix common issues
regexr fix "added anchors: ^pattern$ and escaped special chars"
Preview matches
regexr preview "pattern=[0-9]{3}-[0-9]{4} matched: 555-1234, 800-9999"
View summary statistics
regexr stats
Export all data as JSON
regexr export json
Search logged patterns
regexr search "email"

Output

All commands output to stdout. Redirect to a file if needed:

regexr report "weekly pattern audit" > report.txt
regexr export csv  # saves to ~/.local/share/regexr/export.csv

Configuration

Set DATA_DIR by modifying the script, or use the default: ~/.local/share/regexr/

# Check a regex pattern for issues
regexr check "^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z]{2,}$ — email validation"
Validate regex syntax
regexr validate "(?<=@)[a-z]+\.com — lookbehind syntax OK"
Generate a pattern from description
regexr generate "match IPv4 addresses: \d{1,3}(\.\d{1,3}){3}"
Explain a complex regex
regexr explain "^(?=.*[A-Z])(?=.*\d).{8,}$ — password: 1 uppercase, 1 digit, 8+ chars"
Lint for performance issues
regexr lint "(a+)+ — warning: catastrophic backtracking possible"
Convert between flavors
regexr convert "JS→Python: /\d+/g becomes re.findall(r'\d+', text)"
Fix common issues
regexr fix "added anchors: ^pattern$ and escaped special chars"
Preview matches
regexr preview "pattern=[0-9]{3}-[0-9]{4} matched: 555-1234, 800-9999"
View summary statistics
regexr stats
Export all data as JSON
regexr export json
Search logged patterns
regexr search "email"

Set DATA_DIR by modifying the script, or use the default: ~/.local/share/regexr/