Re: git-archive and tar options

[Jeff King <peff@peff.net>]

On Wed, Jul 13, 2011 at 06:34:32PM -0500, Neal Kreitzinger wrote:

> the git-archive manpage states:
> 
> "git archive [--format=<fmt>] [--list] [--prefix=<prefix>/] [<extra>] [-o 
> | --output=<file>] [--worktree-attributes] [--remote=<repo> 
> [--exec=<git-upload-archive>]] <tree-ish>  [path\u2026]
> 
> <extra>
>     This can be any options that the archiver backend understands. See next 
> section."
>
> I have tar 1.23 and want to use the --transform option.  How can I feed 
> git-archive additional tar options?

Right. And the next section is "Backend Extra Options", which has:

   zip
       -0
           Store the files instead of deflating them.

       -9
           Highest and slowest compression level. You can specify any number from 1 to 9
           to adjust compression speed and ratio.

And nothing else. We don't actually call your system "tar" to generate
the tarball, which is what I assume you thought when you saw "backend".
A patch to make it more clear would be welcome.

> Working syntax starting points for git-archive and tar:
> 
> git archive --format=tar -o my.tar HEAD Web/Templates/
> tar -cvf my.tar --transform 's,^Web/Templates/,myPath/myWeb/Templates/,' 
> WebPortal/Templates/
> 
> Failed syntax attempts for feeding tar option to git-archive:
> 
> git archive --format=tar -o my.tar HEAD --transform 
> 's,^Web/Templates/,myPath/myWeb/Templates/,' WebPortal/Templates/
> error: unknown option `transform'
> 
> git archive --format=tar -o my.tar --transform 
> 's,^Web/Templates/,myPath/myWeb/Templates/,' HEAD WebPortal/Templates/
> error: unknown option `transform'

Yeah, that won't work, because there is no such option. We do have
"--prefix", but I suspect that's not flexible enough for what you want.

So you're probably stuck with extracting the results of "git archive" to
a temporary directory and then using GNU tar to re-archive them (or if
you have a checkout, you can just tar that up directly, feeding the list
from "git ls-files" into tar). It would be nice if GNU tar could act as
a post-processor, and do something like:

  git archive HEAD | tar --pipe-mode --transform=whatever >my.tar

But AFAIK, nothing like "--pipe-mode" exists.

It would probably not be a very hard feature to add to "git archive" if
you're interested in doing so.

-Peff