title: adb logcat -f log.txt error: couldn't open output file: Read-only file system
body: <p>On windows (win7), debugging a real phone via USB I want to dump the logcat log into a file on my PC.  The rate of data is beyond what is usable in eclipse; and I want the whole unfiltered log.</p>
  
  <p>According to the <a href="http://developer.android.com/tools/debugging/debugging-log.html#startingLogcat" rel="noreferrer">logcat command line instructions</a> this should be trivial with</p>
  
  <p><code>logcat -f logfile.txt</code></p>
  
  <p>I'm using <code>adb logcat -f logfile.txt</code> on the windows command line</p>
  
  <p>but this always responds with </p>
  
  <p><code>couldn't open output file: Read-only file system</code></p>
  
  <p>The file system is <em>not</em> read-only.  Creating and writing files there works fine, and a crude redirection such as <code>adb logcat &gt; logfile.txt</code> also works as expected.  Providing the whole path to the log file makes no difference.</p>
  
  <p>I'd like to make use of logcat's <code>-n</code> and <code>-r</code> options but they require <code>-f</code> to work.</p>
  
  <p>Any suggestions?</p>
  
  <hr>
  
  <p>Notes.
  This question is close to <a href="https://askubuntu.com/questions/441167/couldnt-open-output-file-read-only-file-system">one asked on Ubuntu</a> but that has no answers that are useful to me on Windows, and one suggestion that I've already tried and doesn't work.  Most similar references on SO simply quote the help page, saying <code>-f filename</code> should work.</p>
  
  <p>Question edited to keep it up to date with useful comments &amp; responses.</p>