Living / Linked Copy of File without Alias
Use a hard link with ln in Terminal. A hard link points to the file inode rather than the file location as with a symlink.

$ touch foo.txt
$ echo "this is foo" &gt; foo.txt
$ ln foo.txt hardlink
$ cat hardlink
this is foo
$ mkdir bar
$ mv foo.txt bar
$ cat hardlink
this is foo


More on symbolic links vs hard links: https://askubuntu.com/q/108771/562767