Let's say I have a file that looks like:


what I want is an easy way to get


Is there a neat way to automate that process?

Edit: What I was hoping for is something like using a substitution on host[1-4]win using the line number, where I can repeat the replacement using the [1-4] part. Imagine something like


But is there a way to not spell out the four hosts, instead have sed repeat it based on what was found in the [...]?

  • 1
    What did you try?
    – romainl
    Sep 20, 2023 at 4:48
  • 1
    Regular expressions work the other way around. They match existing strings, they don't generate them. Also, all you want is a tiny subset of regular expressions; i.e. you don't want to extend .*. Overall, this sounds more like a task for a scripting language than for an editor. If you run into problems scripting a solution, ask on SO. I'm voting to close as off-topic.
    – Friedrich
    Sep 20, 2023 at 6:18
  • @romainl I had not tried much because I don't even know where to start. So far I had been doing it by making N number of copies manually, and then using the line numbers in a substitution. For example. if the N is at the end, and the line numbers are 112 to 116, I would remove the sqr brackets stuff and do 112,116s/$/\=line('.')-111/
    – deedar huq
    Sep 20, 2023 at 19:11
  • @Friedrich, oh gotcha, thanks. Makes sense I guess. I somehow assumed there has got to be a Vim way of doing this easily
    – deedar huq
    Sep 20, 2023 at 19:14

1 Answer 1


I doubt a simple solution exist for any regular expression but for you case you could:

Define the following function:

function! GenerateLineRange(start, end, i1, i2)
    let ret = ''
    for i in range(a:i1, a:i2)
        let ret = ret . a:start . i . a:end
        if i != a:i2
          let ret = ret . "\n"
    return ret

Use it in a substitution:

:%s/\v(.*)(\[(\d+)-(\d+)\])(.*)/\=GenerateLineRange(submatch(1), submatch(5), submatch(3), submatch(4))
  • 1
    Oh wow, that is extraordinary, it works! Thank you so much! And it is very readable, I get it. Never seen a Vim function before, so I just learnt something massive. Thanks again!
    – deedar huq
    Sep 20, 2023 at 19:25
  • One question, what is the \v in the beginning?
    – deedar huq
    Sep 20, 2023 at 19:34
  • 1
    @deedarhuq \v turns on very magic mode, see :help /\v. It's used to type fewer backslashes to escape special characters.
    – Friedrich
    Sep 20, 2023 at 20:25
  • Thanks for the feedback :-) Welcome to Vim ;-) Sep 20, 2023 at 21:07
  • 1
    Thanks to both of you! VivianDeSmedt and @Friedrich
    – deedar huq
    Sep 23, 2023 at 18:52

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