[GitHub] [solr] magibney commented on a diff in pull request #1328: SOLR-16645: Extend start script to support ss and netstat as alternatives to lsof

["magibney (via GitHub)" <gi...@apache.org>]

magibney commented on code in PR #1328:
URL: https://github.com/apache/solr/pull/1328#discussion_r1096052115


##########
solr/bin/solr:
##########
@@ -2158,6 +2158,35 @@ function mk_writable_dir() {
   fi
 }
 
+# Check whether at least one of lsof/netstat/ss are available
+function get_port_tool() {
+  for tool in 'lsof' 'netstat' 'ss'; do
+      which $tool &> nul
+      if [[ $? -eq 0 ]]; then
+        echo $tool
+        return
+      fi
+  done
+}
+
+# Will get the PID of the java process running on the specified port, if one is running
+# Otherwise empty result. Use get_port_tool to check whether lsof/ss/netstat is installed first
+function check_port_in_use() {
+  local port=$1
+
+  case $(get_port_tool) in
+    lsof)
+      lsof -iTCP:${port} 2>/dev/null | grep "LISTEN" | grep -Eow "java\s*?[0-9]+" | grep -Eow [0-9]+
+      ;;
+    ss)
+      ss -ntpa 2>/dev/null | grep ":${port} " | grep 'LISTEN ' | grep -Eow "\"java\",(pid=)?[0-9]+?" | grep -Eow "[0-9]+"
+      ;;
+    netstat)
+      netstat -nlp 2>/dev/null | grep ":${port} " | grep -Eow " [0-9]+/java" | grep -Eow "[0-9]+"
+      ;;

Review Comment:
   Great! thanks for looking into it. This seems reasonable, and maybe if anyone else wants to weigh in wrt how standard these flags are, that could be helpful.
   
   Assuming continuing to use grep, we really don't _need_ "extended" grep here (`grep -E` -- nor [here](https://github.com/apache/solr/blob/e35347e7cc12d91af91cb38f9cef43ccc7a7b40e/solr/bin/solr#L180)). Removing the `-E` flag would just mean a little bit of extra escaping of special characters in the pattern -- not sure it's worth it, totally fine as-is, just thought I'd mention.



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