Passing optional jvm arguments to java thru batch and shell scripts in command line

java shell batch-file command-line-arguments

11,342

VM arguments should be passed before the class name otherwise the arguments will become your program arguments so your command should be:

java -cp $CLASSPATH "$@" com.foo.Bar

With the above command, you could run with ./barRunner.sh -Dkey2=value2 -Dkey1=value1.

Now a slight issue is that all the arguments are passed as VM arguments. You may also want to pass some arguments to your program. To do that, you could do something like this:

java -cp $CLASSPATH $JVM_ARGS com.foo.Bar "$@"

With the above command, you could pass both JVM arguments and your program arguments like,

JVM_ARGS="-Dkey2=value2 -Dkey1=value1" ./barRunner.sh programArg1 programArg2

11,342

Rao

Updated on June 04, 2022

Comments

Rao about 2 years
Got a java class with main method, say com.foo.Bar. But there are two optional vm(system) arguments for this class, say key1, key2.

Created a batch & shell shell scripts to call the above programs as below respectively.

Contents of Batch File(barRunner.cmd)
```
@echo off
set CLASSPATH=/bla/;/bla/
java -cp %CLASSPATH% com.foo.Bar %*
```
Contents of Shell script(barRunner.sh)
```
export CLASSPATH=/bla/:/bla/
java -cp $CLASSPATH com.foo.Bar $@
```
Now user calling in the below manner, but vm arguments cannot be read by Bar class
```
barRunner.cmd -Dkey1=value1 
```
or
```
./barRunner.sh -Dkey2=value2 -Dkey1=value1
```
Suspect that the vm argument is passed after the class.

How to pass the vm arguments so that they are available before class name?

EDIT:

Have already tried changing script as below and it worked. But the issue if the class has program arguments.
```
java -cp %CLASSPATH% %* com.foo.Bar
```
Also aware of JAVA_OPTS, but it is a bit tedious for naive users; I mean, multiple commands to be run(set JAVA_OPTS in one command & and call the script in another line) and hesitant to use that way.

So thought of checking with forum if there is better way to achieve both vm & program arguments in single line and both args are optional.
- Rishikesh Darandale almost 7 years
  
  Can you try using JAVA_OPTS variable before java command?
- Rishikesh Darandale almost 7 years
  
  Something like this export JAVA_OPTS=... and java $JAVA_OPTS ...
- Rishikesh Darandale almost 7 years
  
  You can take look at this as well.
- Rao almost 7 years
  
  @RishikeshDarandale, aware of JAVA_OPTS, but it is a bit tedious; i mean, multiple commands to be run and hesitant to use that way. So thought of checking with forumn if there is better way. Sorry, I could not mentioned this in the question in hurry.
Rao almost 7 years

I could not mention, but I tried the same way. And landing into the issue mentioned by in the later part of your answer. Are you sure, both JVM_ARGS and calling script in single line?
Marimuthu Madasamy almost 7 years

That specific syntax only works in shell script not for command line. You could, of course, run those separately.
Rao almost 7 years

I felt that I should have been more clear in the question based on the comments and answer. Just updated the question with details. By the way, thank you so much for your swift reply.
Marimuthu Madasamy almost 7 years

Another option might be to treat the first argument as special and treat that as JVM arguments but it feels hacky. A good thing about the solution in the answer is that you don't have to set the JVM args every time. JVM_ARGS is not special either, you could name it BAR_OPTS and set it just once so you're not running two commands every time.
Rao almost 7 years

I got what you say. Actually, the utility is being created for naive users. So, exploring how can it be kept more simple so that there is no confusion and easy for them to use.
Rao almost 7 years

Ok, can't think of better way. I'll take it.