title: data.table fread error - gzip file - set temporary directory
body: <p>I'm attempting to read a <code>.gz</code>-file using data.tables <code>fread</code>-function. I have tried the syntax suggested <a href="https://stackoverflow.com/questions/35644556/using-fread-to-import-csv-file-from-an-archive-into-r-without-extracting-to">here</a>:</p>
  
  <pre><code>dt = fread("gunzip -c myfile.gz")
  </code></pre>
  
  <p>but I get a verbose error message:</p>
  
  <pre><code>Error in fread("gunzip -c myfile.gz") : 
    File is empty: C:\Users\MARK~1.MUR\AppData\Local\Temp\RtmpIBawPA\file498c1c4114ef
  In addition: Warning messages:
  1: running command 'C:\Windows\system32\cmd.exe /c (gunzip -c myfile.gz) &gt; C:\Users\MARK~1.MUR\AppData\Local\Temp\RtmpIBawPA\file498c1c4114ef' had status 1 
  2: In shell(paste("(", input, ") &gt; ", tt, sep = "")) :
    '(gunzip -c 180227.2101.2017.MRE.csv.gz) &gt; C:\Users\MARK~1.MUR\AppData\Local\Temp\RtmpIBawPA\file498c1c4114ef' execution failed with error code 1
  </code></pre>
  
  <p>My guess here is that access to a temporary file is being denied by my IT masters (?). If this is the case how do I set the temporary file path to say the current directory for the unzip?</p>