As "PATH" usually suggested search paths.
 
  LD_PRELOAD=/path/to/glxtrace.so /path/to/application
 
+and it will generate a trace named "application.trace" in the current
+directory.  You can specify the written trace filename by setting the
+TRACE_FILE envirnment variable before running.
+
 * View the trace with
 
  /path/to/tracedump application.trace
 
 
 void SaverThread::run()
 {
-    qputenv("TRACE_PATH", m_fileName.toLocal8Bit());
+    qputenv("TRACE_FILE", m_fileName.toLocal8Bit());
     unsigned id = 0;
     qDebug()<<"saver thread!";
     Trace::Open();
 
     char szFileName[PATH_MAX];
     const char *lpFileName;
 
-    lpFileName = getenv("TRACE_PATH");
+    lpFileName = getenv("TRACE_FILE");
     if (lpFileName) {
         strncpy(szFileName, lpFileName, PATH_MAX);
     }