File Extension Extraction Regex for Go

What this pattern does

This page provides a well-structured, multi-part regular expression for matching file extension extraction, ported and verified for Go. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your Go project — whether you're validating in a Gin handler, a gRPC service, or a command-line tool.

Go Implementation

// File Extension Extraction
// ReDoS-checked | RegexVault — Dev & Systems > File Paths

package validation

import "regexp"

var fileExtensionExtractionRe = regexp.MustCompile(`(?:^|\/)([^\/\s\.]+[\w.]*\.([a-zA-Z0-9]{1,10}))$`)

func ValidateFileExtensionExtraction(s string) bool {
    return fileExtensionExtractionRe.MatchString(s)
}

// Example
// fmt.Println(ValidateFileExtensionExtraction("file.txt")) // true

Test Cases

When to use this pattern

This pattern is drawn from the Dev & Systems > File Paths category and has been checked for ReDoS risk. That matters for Go developers because Go's RE2 engine is inherently safe from catastrophic backtracking, but this pattern has been additionally verified for correctness. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Group 1 = final extension segment. For compound extensions like .tar.gz, extract the last segment (gz). Extension limited to 10 chars. Dotfiles (.gitignore) have no extension.