[SPARK-13358] [SQL] Retrieve grep path when do benchmark

JIRA: https://issues.apache.org/jira/browse/SPARK-13358

When trying to run a benchmark, I found that on my Ubuntu linux grep is not in /usr/bin/ but /bin/. So wondering if it is better to use which to retrieve grep path.

cc davies

Author: Liang-Chi Hsieh <viirya@gmail.com>

Closes #11231 from viirya/benchmark-grep-path.

core/src/main/scala/org/apache/spark/util/Benchmark.scala

@@ -19,6 +19,7 @@ package org.apache.spark.util
 
 import scala.collection.mutable
 import scala.collection.mutable.ArrayBuffer
+import scala.util.Try
 
 import org.apache.commons.lang3.SystemUtils
 
@@ -93,7 +94,10 @@ private[spark] object Benchmark {
     if (SystemUtils.IS_OS_MAC_OSX) {
       Utils.executeAndGetOutput(Seq("/usr/sbin/sysctl", "-n", "machdep.cpu.brand_string"))
     } else if (SystemUtils.IS_OS_LINUX) {
-      Utils.executeAndGetOutput(Seq("/usr/bin/grep", "-m", "1", "\"model name\"", "/proc/cpuinfo"))
+      Try {
+        val grepPath = Utils.executeAndGetOutput(Seq("which", "grep"))
+        Utils.executeAndGetOutput(Seq(grepPath, "-m", "1", "model name", "/proc/cpuinfo"))
+      }.getOrElse("Unknown processor")
     } else {
       System.getenv("PROCESSOR_IDENTIFIER")
     }