When go to the url :
http://<your-machine-name>:<port>/gsdl/cgi-bin/gliserver.pl?cmd=check-installation

I've got this :

Java failed -- do you have the Java run-time installed?
JAVA_HOME environment variable not set. Might not be able to find Java unless in PATH (/sbin:/usr/sbin:/bin:/usr/bin:/usr/X11R6/bin:/usr/local/gsdl/bin/script:/usr/local/gsdl/bin/linux)

GSDLHOME: /usr/local/gsdl
GSDLOS: linux
PATH: /sbin:/usr/sbin:/bin:/usr/bin:/usr/X11R6/bin:/usr/local/gsdl/bin/script:/usr/local/gsdl/bin/linux

or, I've update my path with

JAVA_HOME=/usr/java/j2sdk1.4.2_16
export JAVA_HOME
PATH=$PATH:$JAVA_HOME/bin
export PATH

and it works !!! (I can launch java command with my bash, and also print
both JAVA_HOME and PATH, updated with the location for java directory)

why do greenstone can't find it ?