Improved start-up shell script "start.sh"

Was "run.sh" but renamed to "start.sh" to better complement "stop.sh".
"run.sh" is now a symbolic link to "start.sh"

Reworked Java version check to remove dependency on "bc" tool which
seems not to be installed on some Ubuntu distributions?

Removed -XX:NativeMemoryTracking flag from JVM args.

Fixed incorrect comment regarding java.net.preferIpV4Stack.
Fixed typo in comment.

run.sh

@@ -1,51 +0,0 @@
-#!/bin/sh
-
-# There's no need to run as root, so don't allow it, for security reasons
-if [ "$USER" = "root" ]; then
-	echo "Please su to non-root user before running"
-	exit
-fi
-
-# Validate Java is installed and the minimum version is available
-MIN_JAVA_VER='11'
-
-if command -v java > /dev/null 2>&1; then
-    version=$(java -version 2>&1 | awk -F '"' '/version/ {print $2}')
-    version=$(echo $version | cut -d'.' -f1,2)
-    if [ `echo "${version}>=${MIN_JAVA_VER}" | bc` -eq 1 ]; then
-        echo 'Passed Java version check'
-    else
-        echo 'Please upgrade your Java to version 11 or greater'
-        exit 1
-    fi
-else
-  echo 'Java is not available, please install Java 11 or greater'
-  exit 1
-fi
-
-# No qortal.jar but we have a Maven built one?
-# Be helpful and copy across to correct location
-if [ ! -e qortal.jar -a -f target/qortal*.jar ]; then
-	echo "Copying Maven-built Qortal JAR to correct pathname"
-	cp target/qortal*.jar qortal.jar
-fi
-
-# Limits Java JVM stack size and maximum heap usage.
-# Comment out for bigger systems, e.g. non-routers
-# or when API documentation is enabled
-# JVM_MEMORY_ARGS="-Xss256k -Xmx128m"
-
-# Although java.net.preferIPv4Stack is supposed to be false
-# by default in Java 11, on some platforms (e.g. FreeBSD 12),
-# it is overriden to be true by default. Hence we explicitly
-# set it to true to obtain desired behaviour.
-nohup nice -n 20 java \
-	-Djava.net.preferIPv4Stack=false \
-	-XX:NativeMemoryTracking=summary \
-	${JVM_MEMORY_ARGS} \
-	-jar qortal.jar \
-	1>run.log 2>&1 &
-
-# Save backgrounded process's PID
-echo $! > run.pid
-echo qortal running as pid $!

run.sh

@@ -0,0 +1 @@
+start.sh

start.sh

@@ -0,0 +1,50 @@
+#!/bin/sh
+
+# There's no need to run as root, so don't allow it, for security reasons
+if [ "$USER" = "root" ]; then
+	echo "Please su to non-root user before running"
+	exit
+fi
+
+# Validate Java is installed and the minimum version is available
+MIN_JAVA_VER='11'
+
+if command -v java > /dev/null 2>&1; then
+    # Example: openjdk version "11.0.6" 2020-01-14
+    version=$(java -version 2>&1 | awk -F '"' '/version/ {print $2}' | cut -d'.' -f1,2)
+    if echo "${version}" "${MIN_JAVA_VER}" | awk '{ if ($2 > 0 && $1 >= $2) exit 0; else exit 1}'; then
+        echo 'Passed Java version check'
+    else
+        echo "Please upgrade your Java to version ${MIN_JAVA_VER} or greater"
+        exit 1
+    fi
+else
+  echo "Java is not available, please install Java ${MIN_JAVA_VER} or greater"
+  exit 1
+fi
+
+# No qortal.jar but we have a Maven built one?
+# Be helpful and copy across to correct location
+if [ ! -e qortal.jar -a -f target/qortal*.jar ]; then
+	echo "Copying Maven-built Qortal JAR to correct pathname"
+	cp target/qortal*.jar qortal.jar
+fi
+
+# Limits Java JVM stack size and maximum heap usage.
+# Comment out for bigger systems, e.g. non-routers
+# or when API documentation is enabled
+# JVM_MEMORY_ARGS="-Xss256k -Xmx128m"
+
+# Although java.net.preferIPv4Stack is supposed to be false
+# by default in Java 11, on some platforms (e.g. FreeBSD 12),
+# it is overridden to be true by default. Hence we explicitly
+# set it to false to obtain desired behaviour.
+nohup nice -n 20 java \
+	-Djava.net.preferIPv4Stack=false \
+	${JVM_MEMORY_ARGS} \
+	-jar qortal.jar \
+	1>run.log 2>&1 &
+
+# Save backgrounded process's PID
+echo $! > run.pid
+echo qortal running as pid $!