Shebang Line Regex for PHP
/^#!(/(?:[a-zA-Z0-9._\-]+/)*[a-zA-Z0-9._\-]+)((?:\s+[^\s]+)*)$/All five implementations are free. Switch engines without signing in.
What this pattern does
This page provides a well-structured, multi-part regular expression for matching shebang line, ported and verified for PHP. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your PHP project — whether you're validating in a Laravel validator, a WordPress plugin, or a standalone PHP script.
Php Implementation
<?php
// Shebang Line
// ReDoS-checked | RegexVault — Dev & Systems > Shell
define('SHEBANG_LINE_PATTERN', '/^#!(\/(?:[a-zA-Z0-9._\-]+\/)*[a-zA-Z0-9._\-]+)((?:\s+[^\s]+)*)$/');
function validate_shebang_line(string $input): bool {
return (bool) preg_match(SHEBANG_LINE_PATTERN, $input);
}
// Example
var_dump(validate_shebang_line("#!/bin/bash")); // bool(true)Test Cases
Matches (Valid) | Rejects (Invalid) |
|---|---|
#!/bin/bash | #! /bin/bash |
#!/usr/bin/env python3 | # comment |
#!/usr/bin/env node --experimental-vm-modules | /bin/bash |
#!/bin/sh | #!/ |
#!/usr/bin/perl -w | !#/bin/bash |
When to use this pattern
This pattern is drawn from the Dev & Systems > Shell category and has been checked for ReDoS risk. That matters for PHP developers because especially relevant in PHP where PCRE backtracking limits can trigger silent failures on malicious input. 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
#! with a space before the path is supported by some kernels but not all. Avoid the space for maximum compatibility.
Technical Notes
Groups: 1=interpreter path, 2=arguments. The env idiom (#!/usr/bin/env python3) is preferred for portability. The shebang must be the first two characters of the file.
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