[Tfug] joining two large files on disk...

[JD Rogers]

I'm curious if anyone knows a way to effectively do a "cat file2 >>
file1" to merge two files, but without rewriting the data on disk?

For example, when you "mv file1 file2" the filename is changed, but
the filesystem doesn't have to rewrite the data, so it's quick even
when the files are GB in size. I want to do that, but with a merge.
Not sure if it's possible given how inodes work, but maybe someone
knows something I don't?

Google didn't seem to know, but it may be because I don't know how to
ask the question.

Thanks,
JDR