title: shell script for creating multiple image files ascending order
body: <p>so the thing is, I'm trying to code a shell script that creates multiple image files in an ascending order, but, the ones with only one digit must come with a zero first. I'm a beginner and searching throughout the internet I've found that there are some syntax differences when it comes to the indexing system, so on my computer the following "for" syntax works fine, but I'm sure there's a better approach to that. there it goes:</p>
  
  <pre><code>for i in 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
    do
      if (${i:0:1} == "0") then
        touch "0${i}.jpg"
      else
        touch "$i.jpg"
      fi
    done
  </code></pre>
  
  <p>it returns "bad substitution". is there anything wrong with this approach?</p>