Greenstone upgrades involve installing the latest version in a separate place to your existing installation, then copying over collections, and repeating any interface modifications in the new version. Once you have the new version working, then you need to change to serving up that one instead of the original.
You can choose whether to upgrade to the latest greenstone 2 version, or try out a greenstone 3 version. You can download both from https://sourceforge.net/projects/greenstone/. The download button will give you the greenstone 3 download, or you can click "browse all files", and from there you can choose which version you want.
You can see a greenstone 3 version at www.greenstone.org/greenstone3/library. In our opinion, greenstone 3 looks nicer than greenstone 2. However, if you have done lots of customizations to your library or collections then it might be easier to stick to greenstone 2. Greenstone 3 uses xslt instead of macros, and has xml/xslt based format statements. And the language interfaces other than English are more complete in greenstone 2.
Note, its pretty simple to install both (unless you are on a new mac) and take a look at each one.
The general process, for either version, would be to download the new version into a separate place, NOT on top of the old version. Get it running and make sure the demo collection is working.
Then copy the collections from the old version into the new version. For greenstone 2, you can just copy them over and run the library. If you have added macros to extra.dm then they might need to be modified depending if they still fit in with the latest interface.
For greenstone3, you should copy them over then open them up in GLI. That will change the config files to greenstone 3 versions. You might need to check format statements as the conversion process is not 100% accurate. The collections don't necessarily need to be rebuilt, but the server will need to be restarted to notice the new collections.
Note, if you are running two GLIs (as you would be in this case when you have two greenstones installed) then sometimes it remembers the collect folder from the previous time it was running. So you need to check that it is using the right one. When you select FileāOpen collection in GLI, if the list of collections doesn't look right for the greenstone you are running, or if you just want to check, then you can click 'change directory' and it will show you which collect folder it is using and you can change it if necessary.
If you have modified the main interface, then you can look at doing that next to your new greenstone. Obviously this will be easier to do in greenstone 2 as your old version and the new version both use macro files. the macros will have changed though, so your modifications might need some modification for the new interface.