copy selected history between repostories

copy selected history between repostories

[luisgutz]

Hi All,

This is something I'm not sure how to do with git, or even if it is possible
in git; and because google has not been my friend this time, I though I
would ask here.

I have 2 repositories: repoA and repoB.

repoB is massive. lots of history and files. But it has a set of files
inside a particular dir with 40-60 files that I just realized are better in
repoA.

Is there any way to import that directory into repoA with all it's history,
but NOT the history from the other commits?
Another way of putting is this: can I make git forget the history of all
other commits but those from this directory?


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Re: copy selected history between repostories

[Avery Pennarun]

On 7/18/08, luisgutz <luis@xmos.com> wrote:
>  Is there any way to import that directory into repoA with all it's history,
>  but NOT the history from the other commits?
>  Another way of putting is this: can I make git forget the history of all
>  other commits but those from this directory?

Try cloning the repository, then running git-filter-branch with the
--subdirectory-filter option.  It works quite nicely.

Have fun,

Avery

Re: copy selected history between repostories

[Nick Andrew]

On Fri, Jul 18, 2008 at 09:58:49AM -0700, luisgutz wrote:
> Is there any way to import that directory into repoA with all it's history,
> but NOT the history from the other commits?
> Another way of putting is this: can I make git forget the history of all
> other commits but those from this directory?

I couldn't figure out git-filter-branch, so I did the following,
which worked for me:

First, export commits as patches in mbox format:

	git log -p --first-parent --reverse --pretty=email $* > mbox

Second, run the mbox file through a filter which selectively
renames files (since almost always I want the files in a different
directory in the new repository):

	myfilter scripts=bin perllib=lib < mbox > mbox2

Finally, import into new repo:

	git-am mbox2

It's a bit slow on the import step but it meets my needs at this time.

Nick.

Filter script follows, for what it's worth ...


#!/usr/bin/perl
#	@(#) git-filter-rename.pl
#
#	Read an mbox file containing patches on standard input,
#	modify the filenames within according to a list of substitutions
#	supplied on the command line, and write the modified mbox file
#	to standard output.

my @subs;

foreach (@ARGV) {
	if (/(.*)=(.*)/) {
		my $len = length($1);
		push(@subs, [ $1, $2, $len ]);
	} else {
		print STDERR "Unknown arg: $_\n";
	}
}

while (<STDIN>) {
	chomp;
	my $line = $_;

	if ($line =~ /^(---|\+\+\+) ([ab]\/)(.+)$/) {
		my $line_1 = $1;
		my $line_2 = $2;
		my $line_3 = $3;

		subFilename($line_3);

		print "$line_1 $line_2$line_3\n";
		next;
	}

	if ($line =~ /^diff --git ([ab]\/)(\S+) ([ab]\/)(\S+)/) {
		my ($line_1, $line_2, $line_3, $line_4) = ($1, $2, $3, $4);
		subFilename($line_2);
		subFilename($line_4);
		print "diff --git $line_1$line_2 $line_3$line_4\n";
		next;
	}

	print $line, "\n";
}

exit(0);

# ------------------------------------------------------------------------
# Substitute a filename in-place (modifies argument)
# ------------------------------------------------------------------------

sub subFilename {

	foreach my $lr (@subs) {
		my ($lhs, $rhs, $len) = @$lr;
		if (substr($_[0], 0, $len) eq $lhs) {
			print STDERR "Match on $lhs, $_[0]\n";
			substr($_[0], 0, $len) = $rhs;
			last;
		}
	}
}

Re: copy selected history between repostories

[Johannes Schindelin]

Hi,

On Sat, 19 Jul 2008, Nick Andrew wrote:

> 	myfilter scripts=bin perllib=lib < mbox > mbox2

Note that if your repository only contains text files, "git fast-export | 
my-filter | git fast-import --force" would have worked faster, probably.

But I am glad you figured out how to do what you wanted to do.

Ciao,
Dscho

Re: copy selected history between repostories

[Jeff King]

On Sat, Jul 19, 2008 at 11:01:22AM +1000, Nick Andrew wrote:

> I couldn't figure out git-filter-branch, so I did the following,
> which worked for me:
> 
> First, export commits as patches in mbox format:
> 
> 	git log -p --first-parent --reverse --pretty=email $* > mbox
> [...]
> 
> Finally, import into new repo:
> 
> 	git-am mbox2

Note that this will lose any interesting history topology you had, like
branching and merging (and it may have trouble applying all patches in
that case, too). But if your history was a straight line, it should
produce equivalent results.

-Peff