How to extract part of the line and append it to the end of line in VIM with regex?

Question

I have a file with a number of urls in the form:

http://www.edu-factory.org/wp/about/

I'd like to extract the sitehost of the url and append it to the end of the line:

http://www.edu-factory.org/wp/about/ www.edu-factory.org

Any idea how to do that?

Answer 1

One way to do that:

:s:\(.*//\)\([^/]*\)\(/.*\):\1\2\3 \2:

Explanation:

• :s: - Using substitution
• \(.*//\) - Capture the part up to the double slash (group 1)
• \([^/]*\) - Capture everything that's not a slash (group 2)
• \(/.*\) - Capture the first single slash and everything after it (group 3)
• :\1\2\3 \2: - Output groups 1, 2 and 3 followed by a space and group 2 again

Edit:

You could sorten that to:

:s:\(.*//\)\([^/]*\)\(/.*\):& \2:

The ampersand outputs the whole matched string which includes the whole line since the regex begins and ends with .*. You could use \0 instead of the ampersand.