How to set Java classpath in bash script used in Ubuntu and Windows (Cygwin)

Question

I am writing a bash script that should execute some Java application that needs a specific classpath.

Further, this script should be executable on both, Ubuntu & Windows (Cygwin).

The problem: The seperator on Windows is ";" and the seperator on Ubuntu is ":". This results in java -cp A.jar;B.jar Main on Windows (also when using cygwin, because it's using Windows' java) and java -cp A.jar:B.jar Main on Ubuntu.

The question: How to detect in the bash script which underlying operating system is running / which java classpath seperator to use?

GhostCat · Accepted Answer · 2016-10-12 11:11:00Z

2

A naive (but quick to implement) approach: run uname -a first and push that into a variable. Then check if that output contains "Ubuntu".

If so, you should be using the ":" as separator; otherwise ";" should do.

And if you want to be prepared for other platforms in the future; instead of doing a simple if/else; you might want to check what uname -a has to say on cygwin; to setup some $SEPARATOR_CHAR variable using a bash switch statement.

edited Oct 12, 2016 at 11:11

answered Oct 12, 2016 at 11:05

GhostCat

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2 Comments

Markus Weninger Over a year ago

Thanks for the hint with uname. Since it should also be able to run on Mac (and probably later other *nix), I think it would be best to check what cygwin says. Then I could use ":" as default, while just switching to ";" when uname matches cygwin's (Windows) name

Markus Weninger Over a year ago

I'll just let this question open for some more time, probably more answers will come. If not, this will become the accepted answer.

Markus Weninger · Accepted Answer · 2016-10-12 13:09:47Z

0

Just to provide the final solution:

I just tested uname -s on Ubuntu, Mac, and Windows running cygwin and came up with following script:

if [ "$(uname)" == "Darwin" ]; then
    # Do something under Mac OS X platform
    SEP=":"
elif [ "$(expr substr $(uname -s) 1 5)" == "Linux" ]; then
    # Do something under GNU/Linux platform
    SEP=":"
elif [ "$(expr substr $(uname -s) 1 6)" == "CYGWIN" ]; then
    # Do something under Windows NT platform
    SEP=";"
fi

answered Oct 12, 2016 at 13:09

Markus Weninger

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