title: Unlink function causing an error for consequent `?` and `plot` functions
body: <p>I am using <code>tempdir</code> function to create a temporary directory where I extract .zip files with <code>unzip</code> function. In connection with this, I thought it's good to remove the temporary directories to avoid filling my computer up with scrap data. For this purpose I have been using <code>unlink</code> function. Using <code>unlink</code> function before <code>?</code> or <code>plot</code> functions causes an error on my computer (OS X Mavericks). I have not tested whether this is the case for other operating systems. I did some googling and one theory for similar error message was that this problem could be related to encrypted hard disc. My hard disc is encrypted, so that could match. But I do not understand why should that matter as <code>plot</code> or <code>?</code> functions should not be related to <code>unlink</code> operation in my mind. Here is an example:</p>
  
  <pre><code>location &lt;- tempdir()
  ?plot
  #works
  
  unlink(location, recursive = TRUE)
  ?plot
  # Error in file(out, "wt") : cannot open the connection
  </code></pre>
  
  <p>Plotting works with a warning in R and does not work in R Studio:</p>
  
  <pre><code>plot(1:10)
  # Warning message:
  # In file(out, "wt") :
  # cannot open file #'/var/folders/wh/y62s7qxn29s2lvlx1nh9nxpr0000gq/T//RtmpdYlFVc/Rhttpd175551e9e35fa': No such file or # directory
  </code></pre>
  
  <p>This seems to work in R studio, but not in R:</p>
  
  <pre><code>graphics.off()
  ?plot
  # works again
  plot(1:10)
  # this works now too
  </code></pre>
  
  <p><strong>What is going on here? If the problem is related to my encrypted hard disc, is there a neater way extracting .zip files without generating scrap data?</strong></p>
  
  <p>PS. Here is my session information (I had the same problem with R version 3.0.2):</p>
  
  <pre><code>sessionInfo()
  R version 3.0.3 (2014-03-06)
  Platform: x86_64-apple-darwin10.8.0 (64-bit)
  
  locale:
  [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
  
  attached base packages:
  [1] grDevices datasets  splines   grid      utils     graphics  stats     methods   base     
  
  other attached packages:
   [1] devtools_1.4.1    roxygen2_3.0.0    gridExtra_0.9.1   data.table_1.8.10 xlsx_0.5.5        xlsxjars_0.5.0    rJava_0.9-6      
   [8] reshape2_1.2.2    ggplot2_0.9.3.1   plyr_1.8          Hmisc_3.13-0      Formula_1.1-1     survival_2.37-7   lattice_0.20-24  
  [15] cluster_1.14.4   
  
  loaded via a namespace (and not attached):
   [1] brew_1.0-6         codetools_0.2-8    colorspace_1.2-4   dichromat_2.0-0    digest_0.6.4       evaluate_0.5.1    
   [7] gtable_0.1.2       httr_0.2           labeling_0.2       MASS_7.3-29        memoise_0.1        munsell_0.4.2     
  [13] parallel_3.0.3     proto_0.3-10       RColorBrewer_1.0-5 RCurl_1.95-4.1     scales_0.2.3       stringr_0.6.2     
  [19] tools_3.0.3        whisker_0.3-2     
  </code></pre>