UNIX: ssh + tar + gzip -q = goodness

To retrieve a hierarchy of files from a remote server (or to copy it back to a remote server), I often do something like:

ssh servername "tar cvzf - dirname" | tar xvfz -

However, I usually get the following error message:

gzip: stdin: decompression OK, trailing garbage ignored
tar: Child returned status 2
tar: Error exit delayed from previous errors

Strangely enough, as I write this, I get the error message copying something from one FreeBSD system to another FreeBSD system, but I don't get it when copying something from one FreeBSD system to my Ubuntu system. Weird.

I put up with this problem for years. However, I recently needed to use it in a Makefile. Having an error like that is fine when you're a human, but a non-zero return code is a deal-breaker in a Makefile. I needed to clean up my act.

One easy way to make the problem go away is to not use the "z" flag for both instances of tar. This is somewhat icky, because it really would be nice to have the content gzipped. Otherwise, it could take too long to transfer.

Finally, I found the real solution on the gzip Web site. Instead of passing the "z" flag to tar when untarring, use gunzip separately and pass the "q" flag to tell it to be quiet:

ssh server "tar cvzf - dirname" | gunzip -q | tar xvf -

By the way, as is standard in UNIX, there are plenty of other variations of this tar + ssh idiom. For instance, consider:

ssh server "cd myapplication/share/locale && 
            find . -name '*.po' -o -name '*.mo' |
            xargs tar cvzf -" |
    gunzip -q | tar xvf -