title: R grep with 'AND' logic
body: <p>I'm working with <code>RJDBC</code> on a server whose maintainers frequently update jar versions. Since <code>RJDBC</code> requires classpaths, this poses a problem when paths break. My situation is fortuitous in that the most current jars will always be in the same directory, but the version numbers will have changed. </p>
  
  <p>I'm trying to use a simple <code>grep</code> function in R to isolate which jar I need based on a regex with some <code>AND</code> logic, however R makes this surprisingly difficult...</p>
  
  <p><a href="https://stackoverflow.com/questions/7597559/grep-in-r-with-a-list-of-patterns">This question</a> demonstrates how <code>grep</code> in R can function with the <code>|</code> operator for OR logic, but I can't seem to find similar AND logic operator.</p>
  
  <p>Here's an example:</p>
  
  <pre><code>## Let's say I have three jars in a directory
  jars &lt;- list.files('/the/dir')
  &gt; jars
  [1] "hive-jdbc-1.1.0-cdh5.4.3-standalone.jar" "hive-jdbc-1.1.0-cdh5.4.3.jar" "jython-standalone-2.5.3.jar" 
  </code></pre>
  
  <p>The jar I want is "hive-jdbc-1.1.0-cdh5.4.3-standalone.jar"&mdash;how can I use AND logic in grep to extract it? </p>
  
  <pre><code>## I know that OR logic is supported:
  j &lt;- jars[grep('hive-jdbc|standalone', jars)]
  &gt; j
  [1] "hive-jdbc-1.1.0-cdh5.4.3-standalone.jar" "hive-jdbc-1.1.0-cdh5.4.3.jar" "jython-standalone-2.5.3.jar"
  
  ## Would AND logic look like the same format?
  &gt; jars[grep('hive-jdbc&amp;standalone', jars)]
  character(0)
  </code></pre>
  
  <p>Not all-that-surprisingly, that last piece doesn't work... I found a <a href="https://stat545-ubc.github.io/block022_regular-expression.html" rel="nofollow noreferrer">useful, yet non-comprehensive, link</a> for grep in R, but it doesn't show an AND operator. Any thoughts?</p>