perl regular expression match substring

Question

I have several strings from which I want to extract a substring. Here is an example:

/skukke/integration/build/IO/something

I would like to extract everything after the 3rd / character. In this case, the output should be

/build/IO/something

I tried something like this

/\/\s*([^\\]*)\s*$/

The result of the match is

something

Which is not what I want. Can anyone help?

Answer 1

Regex Solution

The regex you can use is:

(?:\/[^\/]+){2}(.*)

See demo

Regex explanation:

• (?:\/[^\/]+){2} - Match exactly 2 times / and everything that is not / 1 or more times
• (.*) - Match 0 or more characters after what we matched before and put into a capturing group 1.

Here is a demo on TutorialsPoint:

$str = "/skukke/integration/build/IO/something";
print $str =~ /(?:\/[^\/]+){2}(.*)/;

Output:

/build/IO/something

Non-regex solution

You can use File::Spec::Functions:

#!/usr/bin/perl
use File::Spec;
$parentPath = "/skukke/integration";
$filePath = "/skukke/integration/build/IO/something";
my $relativePath = File::Spec->abs2rel ($filePath,  $parentPath);
print "/". $relativePath;

Outputs /build/IO/something.

See demo on Ideone