title: Suppressing messages in Knitr / Rmarkdown
body: <p>Here is the code for my RMarkdown file:</p>
  
  <pre><code>```{r echo=FALSE, message=FALSE}
  opts_chunk$set(comment = NA, echo=FALSE, message = FALSE, warnings = FALSE)
  options("getSymbols.warning4.0"=FALSE)
  Sys.setenv(TZ = "GMT")
  library(quantmod)
  library(xtable)
  library(PerformanceAnalytics)
  ```
  
  ```{r}
  getSymbols("^RUT")
  chart.TimeSeries(RUT)
  dev.off()
  ```
  </code></pre>
  
  <p>Despite settings <code>message = FALSE, warnings = FALSE</code>, I am still getting output messages in the HTML file when I run <code>getSymbols()</code> and <code>dev.off()</code>.  Their respective outputs are:</p>
  
  <pre><code>[1] "RUT"
  </code></pre>
  
  <p>and</p>
  
  <pre><code>null device 
            1 
  </code></pre>
  
  <p>How do I suppress these messages?</p>