Neo4j installation is buggy

[cheerfulstoic]

I've just updated to 5.0.0.rc.2 to use the fixed rake tasks and found two issues with the install task:

When I first run bundle exec rake protected_neo4j_install[community-2.2.2,test] it installs Neo4j in db/neo4j/test/. I get all files directly under the test folder.

If I run the rake task a second time, everything runs again but this time I end up with a neo4j-community-2.2.2 folder inside db/neo4j/test/ and all newly installed files within this new folder.

Subsequent runs will fail with error:

mv: rename neo4j-community-2.2.2 to db/neo4j/test/neo4j-community-2.2.2: Directory not empty
rake aborted!
Unable to run: mv neo4j-community-2.2.2 db/neo4j/test

A way to fix this could be to remove the test directory before trying to move the extracted archive.
I do not have time right now to fork/PR but I have fixed the problem locally for UNIX systems (starting line 113 of neo4j_server.rake):

    else
      system_or_fail("tar -xvf #{downloaded_file}")
      system_or_fail("rm -rf #{install_location(args)}")
      system_or_fail("mv neo4j-#{edition} #{install_location(args)}")
      system_or_fail("rm #{downloaded_file}")
      puts 'Neo4j Installed in to neo4j directory.'
    end

Other issues

• Well first, this fix would shamelessly overwrite everything in an existing DB folder without warning... but as I can tell from how the task works, that was already not a problem (?).
• When the archive already exists in the project's root folder, installation will fail with error:

tar: Option -f requires an argument
Usage:
  List:    tar -tf <archive-filename>
  Extract: tar -xf <archive-filename>
  Create:  tar -cf <archive-filename> [filenames...]
  Help:    tar --help
rake aborted!
Unable to run: tar -xvf

That's because download_neo4j_unless_exists will return nil when the file already exists instead of returning the name of the (already) downloaded file.

[cheerfulstoic]

Moved from neo4jrb/activegraph#823 (comment)