Pattern

Regex for File path (Unix)

Absolute or relative Unix-style file path.

The File path (Unix) regex is ^(?:\/|\.{1,2}\/)?(?:[\w.-]+\/)*[\w.-]+$ — copy it below, or open it in the explainer for a token-by-token breakdown.

The pattern

^(?:\/|\.{1,2}\/)?(?:[\w.-]+\/)*[\w.-]+$

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What it matches

/usr/local/bin/python
./script.sh
../config/app.yml
file.txt

What it doesn't match

C:\Users\bob
path with spaces
/leading/space

Notes & gotchas

Doesn't allow spaces in path components. For paths with spaces, allow them in the character class. Doesn't check the file exists.

Code in your language

Use the explainer's Code tab to generate ready-to-paste snippets in JavaScript, Python, Java, .NET, Go, Ruby, and PHP for this pattern.

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Token-by-token breakdown

Every part of the pattern, left to right:

Token	Meaning
`^`	start of string (or line in multiline mode)
`(?:`	start of a non-capturing group
`\/`	literal “/”
`\|`	OR — try the alternative
`\.{1,2}`	between 1 and 2 times: literal “.”
`\/`	literal “/”
`)?`	end of group, optional (zero or one)
`(?:`	start of a non-capturing group
`[\w.-]+`	one or more: any of: word chars (A–Z, a–z, 0–9, _), “.”, “-”
`\/`	literal “/”
`)*`	end of group, zero or more
`[\w.-]+`	one or more: any of: word chars (A–Z, a–z, 0–9, _), “.”, “-”
`$`	end of string (or line in multiline mode)

About this pattern

Developer-oriented patterns help with code analysis, log parsing, and data transformation. Use these in build scripts, CI tools, and code review utilities.

Quick usage in different languages

This exact pattern — with the correct escaping and idioms for each language:

JavaScript: /^(?:\\/|\.{1,2}\\/)?(?:[\w.-]+\\/)*[\w.-]+$/.test(value)
Python: re.match(r"^(?:\/|\.{1,2}\/)?(?:[\w.-]+\/)*[\w.-]+$", value)
Java: Pattern.compile("^(?:\\/|\\.{1,2}\\/)?(?:[\\w.-]+\\/)*[\\w.-]+$").matcher(value).matches()
C# / .NET: Regex.IsMatch(value, @"^(?:\/|\.{1,2}\/)?(?:[\w.-]+\/)*[\w.-]+$")
Go: regexp.MustCompile(`^(?:\/|\.{1,2}\/)?(?:[\w.-]+\/)*[\w.-]+$`).MatchString(value)
Ruby: /^(?:\\/|\.{1,2}\\/)?(?:[\w.-]+\\/)*[\w.-]+$/.match?(value)
PHP: preg_match('~^(?:\/|\.{1,2}\/)?(?:[\w.-]+\/)*[\w.-]+$~', $value)

The explainer’s Code tab regenerates these for any pattern you paste, and the downloadable cheat sheet bundles the breakdown, all seven snippets, and the pitfalls below onto one printable page.

Common pitfalls

Anchored to the whole string. This pattern uses ^ and $, so it requires the entire input to match. To find it inside a longer text, drop the anchors and use the global (g) flag.
Watch for backtracking. This pattern nests quantifiers; on adversarial input that can cause exponential backtracking (ReDoS). Test with long non-matching strings, or use an RE2-based engine.
Escape it correctly per language. In Java and JavaScript strings each backslash must be doubled (\\d); in Python, Go, and C# use raw/verbatim strings so the backslashes survive.
Validate beyond format. Matching the format doesn't guarantee the value is real. Confirm the file path (unix) against a source of truth (database, API, or checksum) where it matters.

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