. Introduce the JAVAVM_DRYRUN variable. If this is set, then javavm will

not invoke any Java programmes, but will instead print out what it would
  have invoked and some related settings.

  This work was inspired by the PR, but doesn't use its implementation.

PR:		96050

java/javavmwrapper/Makefile

@@ -8,8 +8,7 @@
 #
 
 PORTNAME=	javavmwrapper
-PORTVERSION=	2.1
+PORTVERSION=	2.2
-PORTREVISION=	3
 CATEGORIES=	java
 MASTER_SITES=	# none
 DISTFILES=	# none

java/javavmwrapper/src/javavm.1

@@ -130,11 +130,37 @@ Java VM as options.
 For more information on environment variables which can be used to set
 options see
 .Pa %%PREFIX%%/etc/javavm_opts.conf.dist .
+.It Ev JAVAVM_DRYRUN
+When this variable is set, no Java VM is invoked.
+Instead, the Java VM wrapper prints out the following information:
+.Bl -tag -width indent
+.It Ev JAVA_HOME
+The value of the
+.Ev JAVA_HOME
+environment variable which the Java VM wrapper would have set before
+invoking the Java VM.
+.It Ev JAVAVM_CONF
+The Java VM wrapper configuration file being used.
+.It Ev JAVAVM_OPTS_CONF
+The Java VM wrapper option configuration file being used.
+.It Ev JAVAVM_PROG
+The Java VM that would have been invoked.
+.It Ev JAVAVM_OPTS
+The options that would have been passed to the invoked Java VM.
+It is important to note that this variable may not be the same as the
+.Ev JAVAVM_OPTS
+environment variable due to processing of the Java VM wrapper option
+configuration file.
+.It Ev JAVAVM_COMMAND
+The full command line that would have been used to invoke the Java VM.
+.El
 .El
 .Sh FILES
 .Bl -tag -width indent
 .It Pa %%PREFIX%%/etc/javavms
 The location of the Java VM wrapper configuration file.
+.It Pa %%PREFIX%%/etc/javavm_opts.conf
+The location of the Java VM wrapper option configuration file.
 .It Pa %%PORTSDIR%%/Mk/bsd.java.mk
 The file usually used, along with
 .Nm make ,
@@ -157,6 +183,14 @@ with
 This is necessary if MyApp uses JNI, for instance.
 .It Ev JAVA_VERSION="1.2 1.4" Pa %%LOCALBASE%%/bin/java Fl jar Pa MyApp.jar
 Execute MyApp with either a Java VM that is either version 1.2 or version 1.4.
+.It Ev JAVAVM_DRYRUN=yes Pa %%LOCALBASE%%/bin/java
+Don't invoke the Java VM, but print out information about what would have
+been done.
+This could be used in a script to determine the
+.Ev JAVA_HOME
+that the Java VM wrapper will use, for instance:
+.Lp
+.Ev JAVA_HOME=`env JAVAVM_DRYRUN=yes %%LOCALBASE%%/bin/java | grep '^JAVA_HOME' | cut -c11-`
 .El
 .Sh SEE ALSO
 .Xr checkvms 1 ,

java/javavmwrapper/src/javavmwrapper.sh

@@ -42,6 +42,17 @@ _JAVAVM_MAKE=/usr/bin/make
 # Try to run a Java command.
 #
 tryJavaCommand () {
+    # If this is a test run, spit out the configuration and exit
+    if [ -n "${JAVAVM_DRYRUN}" ]; then
+	echo "JAVA_HOME=${JAVA_HOME}"
+	echo "JAVAVM_CONF=${_JAVAVM_CONF}"
+	echo "JAVAVM_OPTS_CONF=${_JAVAVM_OPTS_CONF}"
+	echo "JAVAVM_PROG=${1}"
+	echo "JAVAVM_OPTS=${_JAVAVM_OPTS}"
+	echo "JAVAVM_COMMAND=${@}"
+        exit 0
+    fi
+
     # Check for the command being executable and exec it if so.
     if [ -x "${1}" ]; then
         if [ -n "${_JAVAVM_SAVE_PATH}" ]; then
@@ -67,16 +78,16 @@ setJavaOptions () {
 
     # Possible environment variables are stackable
     if [ -n "${JAVA_HOME_PROG_OPTS}" ]; then
-        _JAVAVM_OPTS="${_JAVAVM_OPTS} ${JAVA_HOME_PROG_OPTS}"
+        _JAVAVM_OPTS="${JAVA_HOME_PROG_OPTS} ${_JAVAVM_OPTS}"
     fi
     if [ -n "${JAVA_HOME_OPTS}" ]; then
-        _JAVAVM_OPTS="${_JAVAVM_OPTS} ${JAVA_HOME_OPTS}"
+        _JAVAVM_OPTS="${JAVA_HOME_OPTS} ${_JAVAVM_OPTS}"
     fi
     if [ -n "${PROG_OPTS}" ]; then
-        _JAVAVM_OPTS="${_JAVAVM_OPTS} ${PROG_OPTS}"
+        _JAVAVM_OPTS="${PROG_OPTS} ${_JAVAVM_OPTS}"
     fi
     if [ -n "${JAVAVM_OPTS}" ]; then
-        _JAVAVM_OPTS="${_JAVAVM_OPTS} ${JAVAVM_OPTS}"
+        _JAVAVM_OPTS="${JAVAVM_OPTS} ${_JAVAVM_OPTS}"
     fi
 }