title: Using variables in command line
body: <p>I wrote a code and it works great but I need to use variables instead static numbers for scopes 8 and 16</p>
  
  <pre><code>cat /etc/passwd | sed '/^#/d' | sed -n 'n;p' | sed 's/:\(.*\) //g' | sed 's/ /,/g' | sed 's/\(.*\),/\1./' | sort -r | sed 's/*rav://g' | sed "s/:.*//" | rev | sed -n -e '8,16p' | xargs | sed -e 's/ /, /g' | sed '/:[0-9]*$/ ! s/$/./'
  </code></pre>
  
  <p>I've changed the code to </p>
  
  <pre><code>cat /etc/passwd | sed '/^#/d' | sed -n 'n;p' | sed 's/:\(.*\) //g' | sed 's/ /,/g' | sed 's/\(.*\),/\1./' | sort -r | sed 's/*rav://g' | sed "s/:.*//" | rev | sed -n -e '$FT_LINE1,$FT_LINE2+p' | xargs | sed -e 's/ /, /g' | sed '/:[0-9]*$/ ! s/$/./'
  </code></pre>
  
  <p>but I got a error </p>
  
  <pre><code>sed: 1: "$FT_LINE1,$FT_LINE2p": invalid command code F
  </code></pre>