View the original community article here
Last tested: Jun 26, 2020
If on Linux:
In layman's terms, you're ok. In Linux, files aren't actually deleted if they're still in use. Keep a backup of the jar, just in case, but you should be fine.
a file isn't really deleted until all applications that have it opened close it. The file will be gone from the directory listing, but it still exists and can be read (and even written!) by any application with a valid file descriptor open.
When you "rm looker.jar", the kernel is ultimately unlinking that filename from the disk block. The running looker process will have already mapped the file into memory and will still have a reference to it