git-commit-vandalism/Documentation/git-merge-file.txt
Junio C Hamano 73eb40eeaa git-merge-file --ours, --theirs
Sometimes people want their conflicting merges autoresolved by
favouring upstream changes.  The standard answer they are given is
to run "git diff --name-only | xargs git checkout MERGE_HEAD --" in
such a case.  This is to accept automerge results for the paths that
are fully resolved automatically, while taking their version of the
file in full for paths that have conflicts.

This is problematic on two counts.

One is that this is not exactly what these people want.  It discards
all changes they did on their branch for any paths that conflicted.
They usually want to salvage as much automerge result as possible in
a conflicted file, and want to take the upstream change only in the
conflicted part.

This patch teaches two new modes of operation to the lowest-lever
merge machinery, xdl_merge().  Instead of leaving the conflicted
lines from both sides enclosed in <<<, ===, and >>> markers, the
conflicts are resolved favouring our side or their side of changes.

A larger problem is that this tends to encourage a bad workflow by
allowing people to record such a mixed up half-merged result as a
full commit without auditing.  This commit does not tackle this
issue at all.  In git, we usually give long enough rope to users
with strange wishes as long as the risky features are not enabled by
default, and this is such a risky feature.

Signed-off-by: Avery Pennarun <apenwarr@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-11-29 23:11:46 -08:00

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git-merge-file(1)
=================
NAME
----
git-merge-file - Run a three-way file merge
SYNOPSIS
--------
[verse]
'git merge-file' [-L <current-name> [-L <base-name> [-L <other-name>]]]
[--ours|--theirs] [-p|--stdout] [-q|--quiet]
<current-file> <base-file> <other-file>
DESCRIPTION
-----------
'git-merge-file' incorporates all changes that lead from the `<base-file>`
to `<other-file>` into `<current-file>`. The result ordinarily goes into
`<current-file>`. 'git-merge-file' is useful for combining separate changes
to an original. Suppose `<base-file>` is the original, and both
`<current-file>` and `<other-file>` are modifications of `<base-file>`,
then 'git-merge-file' combines both changes.
A conflict occurs if both `<current-file>` and `<other-file>` have changes
in a common segment of lines. If a conflict is found, 'git-merge-file'
normally outputs a warning and brackets the conflict with lines containing
<<<<<<< and >>>>>>> markers. A typical conflict will look like this:
<<<<<<< A
lines in file A
=======
lines in file B
>>>>>>> B
If there are conflicts, the user should edit the result and delete one of
the alternatives. When `--ours` or `--theirs` option is in effect, however,
these conflicts are resolved favouring lines from `<current-file>` or
lines from `<other-file>` respectively.
The exit value of this program is negative on error, and the number of
conflicts otherwise. If the merge was clean, the exit value is 0.
'git-merge-file' is designed to be a minimal clone of RCS 'merge'; that is, it
implements all of RCS 'merge''s functionality which is needed by
linkgit:git[1].
OPTIONS
-------
-L <label>::
This option may be given up to three times, and
specifies labels to be used in place of the
corresponding file names in conflict reports. That is,
`git merge-file -L x -L y -L z a b c` generates output that
looks like it came from files x, y and z instead of
from files a, b and c.
-p::
Send results to standard output instead of overwriting
`<current-file>`.
-q::
Quiet; do not warn about conflicts.
--ours::
--theirs::
Instead of leaving conflicts in the file, resolve conflicts
favouring our (or their) side of the lines.
EXAMPLES
--------
git merge-file README.my README README.upstream::
combines the changes of README.my and README.upstream since README,
tries to merge them and writes the result into README.my.
git merge-file -L a -L b -L c tmp/a123 tmp/b234 tmp/c345::
merges tmp/a123 and tmp/c345 with the base tmp/b234, but uses labels
`a` and `c` instead of `tmp/a123` and `tmp/c345`.
Author
------
Written by Johannes Schindelin <johannes.schindelin@gmx.de>
Documentation
--------------
Documentation by Johannes Schindelin and the git-list <git@vger.kernel.org>,
with parts copied from the original documentation of RCS 'merge'.
GIT
---
Part of the linkgit:git[1] suite