title: Ambiguous redirect error in shell scripting when creating file name with date
body: <p>I'm trying to make this temperature log in Raspberry Pi happen (though some of the code did not work therefore I used slightly diff. solutions):</p>
  
  <p><a href="https://www.raspberrypi.org/learning/temperature-log/worksheet/" rel="nofollow">https://www.raspberrypi.org/learning/temperature-log/worksheet/</a></p>
  
  <p>I'm stuck with writing the results in a file. I want to create a file that's name contains the actual date, e.g. temperature_log_2016_08_13.txt</p>
  
  <p>When running the script I get an <em>ambiguous redirection error</em> each time lines with the echo commands execute. I tried all sort of combinations with quotes, double-quotes, no quotes. Pls advice.</p>
  
  <pre><code>#!/bin/bash
  
  timestamp() {
      date +%F_%H-%M-%S
  }
  
  temperature() {
      /opt/vc/bin/vcgencmd measure_temp
  }
  
  temp=$(temperature)
  temp2=${temp:5:9}
  
  echo Temperature Log_$(date) &gt;/home/pi/logs/temperature_log_$(date).txt
  
  for i in {1..5}
  do
      echo ${temp2} $(timestamp) &gt;&gt;/home/pi/logs/temperature_log_$(date).txt
      sleep 1
  done
  </code></pre>
  
  <p>UPDATE: by putting the file name between quotation marks, as advised below, the ambiguous redirect error is gone, but instead the script produces 5 files with the date/timestamp in its name. I need only 1 file into which all the temperatures are written.</p>