title: pandoc version 1.12.3 or higher is required and was not found (R shiny)
body: <p>I have a problem generating a pdf report from my app shiny which is hosted on a server. </p>
  
  <p>the app works fine but when I press the button to download the report, I get this error :</p>
  
  <pre><code> pandoc version 1.12.3 or higher is required and was not found.
  </code></pre>
  
  <p>The proble is that if I type <code>pandoc -v</code> I get:</p>
  
  <pre><code> pandoc 1.12.3.3
   Compiled with texmath 0.6.6, highlighting-kate 0.5.6.1.
  Syntax highlighting is supported for the following languages:
      actionscript, ada, apache, asn1, asp, awk, bash, bibtex, boo, c, changelog,
      clojure, cmake, coffee, coldfusion, commonlisp, cpp, cs, css, curry, d,
      diff, djangotemplate, doxygen, doxygenlua, dtd, eiffel, email, erlang,
      fortran, fsharp, gnuassembler, go, haskell, haxe, html, ini, java, javadoc,
      javascript, json, jsp, julia, latex, lex, literatecurry, literatehaskell,
      lua, makefile, mandoc, markdown, matlab, maxima, metafont, mips, modelines,
      modula2, modula3, monobasic, nasm, noweb, objectivec, objectivecpp, ocaml,
      octave, pascal, perl, php, pike, postscript, prolog, python, r,
      relaxngcompact, restructuredtext, rhtml, roff, ruby, rust, scala, scheme,
      sci, sed, sgml, sql, sqlmysql, sqlpostgresql, tcl, texinfo, verilog, vhdl,
      xml, xorg, xslt, xul, yacc, yaml
   Default user data directory: /home/daniele/.pandoc
   Copyright (C) 2006-2013 John MacFarlane
   Web:  http://johnmacfarlane.net/pandoc
   This is free software; see the source for copying conditions.  There is no
   warranty, not even for merchantability or fitness for a particular purpose.
  </code></pre>
  
  <p>So I suppose I have the right version for that. TexLive is also installed and the path is in <code>$PATH</code>.</p>
  
  <p><strong>Server.R</strong></p>
  
  <pre><code>library(shiny)
  library(drsmooth)
  library(shinyBS)
  library(knitr)
  library(xtable)
  library(rmarkdown)
  
  shinyServer(function(input, output,session) { 
  
   output$downloadReport &lt;- downloadHandler(
  filename = function() {
    paste('report', sep = '.','pdf')
  },
  
  content = function(file) {
    src &lt;- normalizePath('report.Rmd')
  
    # temporarily switch to the temp dir, in case you do not have write
    # permission to the current working directory
    owd &lt;- setwd(tempdir())
    on.exit(setwd(owd))
    file.copy(src, 'report.Rmd')
  
    library(rmarkdown)
    out &lt;- render('report.Rmd')
    file.rename(out, file)
  })
  
  output$tb &lt;- renderUI({
               p(h4("Report")),
              "Dowload a the report of your analysis in a pdf format",
              tags$br(),downloadButton('downloadReport',label="Download report"),
              tags$em("This option will be available soon")
       })
  })
  </code></pre>
  
  <p><strong>* report.Rmd*</strong> does not contain any sort of calculation, it's only text.
  The pdf generation works fine on my local version (MacOS) but not on the server.</p>
  
  <p>I'm here to give other information if needed.</p>