Is there any tool to create Dynamic file content?

Question

Let's say I want to create a file with the following content:

Line1
Line2
Line3
Line4

You'd instantly think in something like:

for i in 1 to 4:
 print "Line"+ i

I have done this before with Vagrant. I did a Nginx configuration like this:

worker_processes  1;
events {
   worker_connections 1024;
}
http {
    upstream servers {
    <% @ips.each do |ip| %>
       <%= 'server ' + ip + ' ;'%>  
    <% end %>
    }
    server {
        listen 8080;
        location / {
              proxy_pass http://servers;
        }
    }
}

But I'm not the know-it-all guy when it comes to technologies, so I'm not sure if this syntax is a Vagrant thing only because that is clearly Ruby.

My questions are:

• Is there any way to do the same in Docker? I mean native Docker.
• Is there any techonolgy independent from the virtualization means that can do the same without being too "Linuxish". I mean, almost Ruby, Java or Python code.
• Is there any techonolgy that has the Linux feeling?

Feel free to answer any of the questions.

Answer 1

Using a shell script (most "native language" in this forum):

#!/bin/sh

i=1

while [ "$i" -le 4 ]; do
   printf "line%d\n" "$i"
   i="$(( i + 1 ))"
done >output_file

Or with bash or ksh93:

#!/bin/bash

printf "line%d\n" {1..4} >output_file

Alternatively,

#!/bin/bash

for ((i = 1; i <= 4; ++i)); do
  printf "line%d" "$i"
done >output_file