Regex pattern to validate Linux folder path
Solution 1
Issue with your RegEx
Your supplied RegEx is working on the test-cases.
You could even reduce it by removing backslashes \\
and outer pair of parentheses. Begin ^
and end $
are only needed once (around the two alternatives).
Possible Solution using Regular Expression
You can test the RegEx on RegexPlanet.com (click on Java-Button for tests)
^/|(/[a-zA-Z0-9_-]+)+$
or equivalent (see demo on RegexPlanet)
^/|(/[\w-]+)+$
Explained:
\w
matches a word-character (same as [a-zA-Z0-9_]
, not matching the dash).
Implementation in Java code:
public boolean isValidLinuxDirectory(String path) {
Pattern linuxDirectoryPattern = Pattern.compile("^/|(/[a-zA-Z0-9_-]+)+$");
return path != null && !path.trim().isEmpty() && linuxDirectoryPattern.matcher( path ).matches();
}
Alternative Solution using File
Note the docs on isDirectory():
Returns:
true
if and only if the file denoted by this abstract pathname exists and is a directory;false
otherwise
So it may only validate your requirements (valid Linux folder) if run on a Linux machine and if the folder/directory exists.
public boolean isValidExistingDirectory(String path) {
if (path == null || path.trim().isEmpty()) return false;
File file = new File( path );
return file.isDirectory();
}
Extended Solution
As stated in comment the special form of root //
should also be valid. Then use this RegEx:
^/|//|(/[\w-]+)+$
It supports:
- root-directory
/
- special form of root-directory
//
- any non-root directory, which name is composed out of alphas, numbers, dash or underscore (e.g.
/abc/123/_abc-123
)
See also
- What is the most correct regular expression for a UNIX file path?
- Regular expression to validate windows and linux path with extension
- what is path //, how is it different from /
Solution 2
Here ya go:
\/[a-zA-Z0-9_\/-]*[^\/]$
EDIT
First character matches a forward slash /
. The following character group matches a-z, A-Z, 0-9, underscores, forward slashes, and dashes (all accepted directory and filename characters). The following asterisk makes the pattern match that character group 0 or more times (so any combo of those characters). The last character group has a negation ^
meaning it matches anything EXCEPT what's in the character group, being the final forward slash that we don't want to match. Finally the $
to end the string.
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afrey
Updated on July 06, 2022Comments
-
afrey almost 2 years
Using JAVA. I am trying to find a more elegant way for validating a Linux folder path (not including the file name).
What I have so far is this:
"^\\/$|^((\\/([a-zA-Z0-9_-]+))+)$"
Folder paths should include only following characters: letters, numbers, dashes or underscore.
Test cases
Valid/ matches:
/
/abc
/abc/abc/abc/abc
Invalid / not-matches:
- null or empty string
/abc/
/abc/abc/abc/abc/
-
Logan Rodie about 5 yearsAlso if you can actually use the filesystem take a look at this
-
afrey about 5 yearsThanks a bunch! Very helpful!
-
afrey about 5 years
^/|/[a-zA-Z0-9_-]+)+$
does not work for the case where the folder path is//
.^/$|^(/[a-zA-Z0-9_-]+)+$
works. -
hc_dev about 5 years@afrey OK. Then please UPDATE your question for extended requirement (as I just did). Sure that your regex
^/$|^(/[a-zA-Z0-9_-]+)+$
does match the special-root (//
) ??