Question

I have this bash file:

#/bin/bash

PROP="-Dprop=foo bar"

java $PROP -jar Foo.jar

So, what I want to do here is pass a space-separated list as a System Property. But this somehow does not work:

Caused by: java.lang.ClassNotFoundException: bar

So, it seems that Bash breaks -Dprop=foo bar up into -Dprop=foo, bar. I tried everything from double quoting to escaping the space character but nothing seems to work.

Answer 1

Note that this is really a shell syntax question … applied to a Java use-case. These answers will work for any use-cases where you need to expand shell variables on a command line while passing embedded spaces from the shell variables to the command in its arguments.

You need to add the quotation marks around the shell script $PROP expansion:

PROP="-Dprop=foo bar"
java "$PROP" -jar Foo.jar

For multiple -D properties:

PROP="-Dprop1=foo bar"
PROP2="-Dprop2=bing bong"
java "$PROP" "$PROP2" -jar Foo.jar

Yes, the multiple -D properties case is cumbersome¹.

Embedding quotes in the shell variable (as some people suggested) does not work².

Finally, you can pass options to the Java command using the @file mechanism, and you could generate an @-file on the fly to inject shell parameters into it. But the end result is (IMO) liable to be worse than the problem that you are trying to fix.

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^{1 – If there is a better way to handle the multiple properties case … that actually works for sh, bash or ksh … please comment below.
2 – Try it and see!}