title: Shell script: Define a variable within an if-statement
body: <p>In a shell program, I would like to define a month variable within an if-statement as below. But I cannot seem to define a variable within the if-statement -- I keep geting an error message that says "command 'dmonth' not found." Any help will be much appreciated! </p>
  
  <pre><code>    #Enter date:
  
      echo "Enter close-out date of MONTHLY data (in the form mmdd): "
      read usedate
      echo " "
  
      #Extract first two digits of "usedate" to get the month number:
  
      dmonthn=${usedate:0:2}
      echo "month number = ${dmonthn}"
      echo " "
  
      #Translate the numeric month identifier into first three letters of month:
  
      if [ "$dmonthn" == "01" ]; then
          dmonth = 'Jan'
      elif [ "$dmonthn" == "02" ]; then 
          dmonth = "Feb" 
      elif [ "$dmonthn" == "03" ]; then 
          dmonth = "Mar" 
      elif [ "$dmonthn" == "04" ]; then 
          dmonth = "Apr" 
      elif [ "$dmonthn" == "05" ]; then 
          dmonth = "May" 
      elif [ "$dmonthn" == "06" ]; then 
          dmonth = "Jun" 
      elif [ "$dmonthn" == "07" ]; then
          dmonth = "Jul" 
      elif [ "$dmonthn" == "08" ]; then 
          dmonth = "Aug" 
      elif [ "$dmonthn" == "09" ]; then 
          dmonth = "Sep" 
      elif [ "$dmonthn" == "10" ]; then 
          dmonth = "Oct"
      elif [ "$dmonthn" == "11" ]; then 
          dmonth = "Nov"
      else 
          dmonth = "Dec" 
      fi
  
      echo dmonth
  </code></pre>