title: ls with numeric range doesn't work inside bash script
body: <p>I have a folder with files named as <code>file_1.ext...file_90.ext</code>. I can list a range of them with the following command:</p>
  
  <pre><code>$ ls /home/rasoul/myfolder/file_{6..19}.ext
  </code></pre>
  
  <p>but when I want to use this command inside a bash script, it doesn't work. Here is a minimal example:</p>
  
  <pre><code>#!/bin/bash
  
  DIR=$1
  st=$2
  ed=$3
  
  FILES=`ls ${DIR}/file\_\{$st..$ed\}.ext`
  for f in $FILES; do
    echo $f
  done
  </code></pre>
  
  <p>running it as,</p>
  
  <pre><code>$ bash test_script.sh /home/rasoul/myfolder 6 19
  </code></pre>
  
  <p>outputs the following error message:</p>
  
  <pre><code>ls: cannot access /home/rasoul/myfolder/file_{6..19}.ext: No such file or directory
  </code></pre>