I recently migrated a number of websites from a server running RHEL 6 to one running RHEL 7. One site uses pdftk, which has a dependency on libgcj, which is apparently no longer supported under RHEL 7. (At least, I have not found a repo advertising it.) It seems that libgcj is required to compile pdftk from source.
I still have access to the old server. It has a compiled binary of pdftk. Is it possible I could just copy that over to the new RHEL 7 server, even though it was compiled in RHEL 6? What would the risks be of testing this theory out? (i.e. can I damage anything trying this?)
So long as you are using the same architecture and not going from a 64bit server to a 32bit server this should work.
You may need to fulfill some library dependencies. Indeed a quick Google seems to imply that libgcj is needed and no longer is available in RHEL7.
There is very little that can go wrong and you probably won't damage your system. Worse case scenario is, you'll get an error saying a library is missing or its the wrong architecture.