@tim_yates. ( UNIX).
1- grails opt:
/opt/grails-2.3.1
/opt/grails-2.5.3
/opt/grails-3.1.1
2- grails.sh . ( /opt/grails-selector)
~/.bash_profile. PATH var , grails.sh. GRAILS_HOME ( , , , , .
export PATH=$PATH:/opt/grails-selector
export GRAILS_HOME=/opt/grails-3.1.9
4- . , . grails, grails.sh, , . , .