Regex for valid directory path

Question

I'm trying to create regex to check against a valid directory prefix, where directory names must not be empty, and can contain any alphabet characters [a-zA-Z] and any numbers [0-9]. They can also contain dashes (-) and underscores (_) but no other special characters. A directory prefix can contain any number of forward slashes (/), and a valid path must not end with a forward slash (/) either.

Valid examples would be:

/abc/def
/hello_123/world-456
/ (a special case where a single forward slash is allowed)

Invalid examples would be:

/abc/def/
/abc//def
//
abc/def
/abc/def/file.txt

So far I have ^(\/+(?!\/))[A-Za-z0-9\/\-_]+$ but it's not checking against what would be empty directory names (e.g. two forward slashed one after the other /abc//def), or path's ending with a slash (e.g. /hello_123/world-456/)

Tangentially, slash is not a regex metacharacter, and doesn't need backslash escaping in many regex dialects. In violation of the regex tag guidance, your question fails to reveal which regex tool you need help with. — tripleee
– tripleee, Commented Jul 9, 2022 at 19:06
/+ will match ALL slashes, so (?!\/) will always be true. — Poul Bak
– Poul Bak, Commented Jul 9, 2022 at 21:53

Luatic · Accepted Answer · 2022-07-09 19:48:51Z

4

I propose ^((/[a-zA-Z0-9-_]+)+|/)$. Explanation:

^ and $: Match the entire string/line
(/[a-zA-Z0-9-_]+)+: One or more directories, starting with slash, separated by slashes; each directory must consist of one or more characters of your charset
(...)+|/: Explicitly allow just a single slash

You might want to use noncapturing groups (?:...) here: ^(?:(?:/[a-zA-Z0-9-_]+)+|/)$. If you only use regex match "testing" this won't matter though.

Side note: Do you want to allow directory names to start with -, _ or a number? This is fairly unusual for names in most naming schemes. You might want to use [a-zA-Z][a-zA-Z0-9-_]* to require a leading letter.

edited Jul 9, 2022 at 19:48

answered Jul 9, 2022 at 19:07

Luatic

11.3k3 gold badges20 silver badges40 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Felipe N Moura · Accepted Answer · 2024-10-09 20:54:46Z

0

In case someone is looking for a function to check whether a value is a path or not, here it goes:

function isPath (value = "") {
  return value.toString()
    .replace(/\\/g, '/')
    .match(
      /^(\/?([a-zA-Z0-9-_,\.])+)+$/
    );
}

If you DO NOT want to accept files in your path, remove the \. in the end of the RX.

Also, if you want to check if something is a real url, the most straight forward to do to that is to use the native checker for you:

function isURL (value = "") {
  try {
    new URL(value);
    return true;
  } catch (error) {
    return false;
  }
}

answered Oct 9, 2024 at 20:54

Felipe N Moura

1,73516 silver badges15 bronze badges

Collectives™ on Stack Overflow

Regex for valid directory path

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related