We are using Grails actively to develop web applications. So we ended up with different applications using different versions of framework.

Setting up GRAILS_HOME variable to point to different Grails release each time I switched to other application was really unpleasant hassle. So I thought about how to resolve this problem. Grails stores application version in application.properties file, I came out to the following Bash script:

#!/bin/bash

# Get required Grails version
GRAILS_VERSION=`sed -n 's/app.grails.version=\(.*\)$/\1/p' <  application.properties` 

# Set Grails home using configured prefix and determined version
export GRAILS_HOME=$GRAILS_PREFIX$GRAILS_VERSION

# Run original Grails script
$GRAILS_HOME/bin/grails $@

It just parses the version from the application.properties file and appends it to GRAILS_PREFIX environment variable. The resulting value is exported into GRAILS_HOME variable.

To use the aforementioned script you need to set GRAILS_PREFIX variable to a value appropriate for your system. And of course your Grails distributions should be installed side-by-side in one common folder.
For example I have it set to /home/vg/tools/grails- on my Linux box.

You can grab/fork script easily as a Gist on GitHub.

UPD: The script was updated to take some corner cases into account. See updated version of the script.

UPD 2: There is also version for Windows.

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