GIT-MERGETOOL(1) Git Manual GIT-MERGETOOL(1)

NAME

git-mergetool - Run merge conflict resolution tools to resolve merge
conflicts

SYNOPSIS

git mergetool [--tool=<tool>] [-y | --[no-]prompt] [<file>...]

DESCRIPTION

Use git mergetool to run one of several merge utilities to resolve
merge conflicts. It is typically run after git merge.

If one or more <file> parameters are given, the merge tool program
will be run to resolve differences in each file (skipping those
without conflicts). Specifying a directory will include all
unresolved files in that path. If no <file> names are specified, git
mergetool will run the merge tool program on every file with merge
conflicts.

OPTIONS

-t <tool>, --tool=<tool>
Use the merge resolution program specified by <tool>. Valid
values include emerge, gvimdiff, kdiff3, meld, vimdiff, and
tortoisemerge. Run git mergetool --tool-help for the list of
valid <tool> settings.

If a merge resolution program is not specified, git mergetool
will use the configuration variable merge.tool. If the
configuration variable merge.tool is not set, git mergetool will
pick a suitable default.

You can explicitly provide a full path to the tool by setting the
configuration variable mergetool.<tool>.path. For example, you
can configure the absolute path to kdiff3 by setting
mergetool.kdiff3.path. Otherwise, git mergetool assumes the tool
is available in PATH.

Instead of running one of the known merge tool programs, git
mergetool can be customized to run an alternative program by
specifying the command line to invoke in a configuration variable
mergetool.<tool>.cmd.

When git mergetool is invoked with this tool (either through the
-t or --tool option or the merge.tool configuration variable),
the configured command line will be invoked with $BASE set to the
name of a temporary file containing the common base for the
merge, if available; $LOCAL set to the name of a temporary file
containing the contents of the file on the current branch;
$REMOTE set to the name of a temporary file containing the
contents of the file to be merged, and $MERGED set to the name of
the file to which the merge tool should write the result of the
merge resolution.

If the custom merge tool correctly indicates the success of a
merge resolution with its exit code, then the configuration
variable mergetool.<tool>.trustExitCode can be set to true.
Otherwise, git mergetool will prompt the user to indicate the
success of the resolution after the custom tool has exited.

--tool-help
Print a list of merge tools that may be used with --tool.

-y, --no-prompt
Don't prompt before each invocation of the merge resolution
program. This is the default if the merge resolution program is
explicitly specified with the --tool option or with the
merge.tool configuration variable.

--prompt
Prompt before each invocation of the merge resolution program to
give the user a chance to skip the path.

-g, --gui
When git-mergetool is invoked with the -g or --gui option, the
default merge tool will be read from the configured merge.guitool
variable instead of merge.tool. If merge.guitool is not set, we
will fallback to the tool configured under merge.tool. This may
be autoselected using the configuration variable
mergetool.guiDefault.

--no-gui
This overrides a previous -g or --gui setting or
mergetool.guiDefault configuration and reads the default merge
tool from the configured merge.tool variable.

-O<orderfile>
Process files in the order specified in the <orderfile>, which
has one shell glob pattern per line. This overrides the
diff.orderFile configuration variable (see git-config(1)). To
cancel diff.orderFile, use -O/dev/null.

CONFIGURATION

Everything below this line in this section is selectively included
from the git-config(1) documentation. The content is the same as
what's found there:

mergetool.<tool>.path
Override the path for the given tool. This is useful in case your
tool is not in the PATH.

mergetool.<tool>.cmd
Specify the command to invoke the specified merge tool. The
specified command is evaluated in shell with the following
variables available: BASE is the name of a temporary file
containing the common base of the files to be merged, if
available; LOCAL is the name of a temporary file containing the
contents of the file on the current branch; REMOTE is the name of
a temporary file containing the contents of the file from the
branch being merged; MERGED contains the name of the file to
which the merge tool should write the results of a successful
merge.

mergetool.<tool>.hideResolved
Allows the user to override the global mergetool.hideResolved
value for a specific tool. See mergetool.hideResolved for the
full description.

mergetool.<tool>.trustExitCode
For a custom merge command, specify whether the exit code of the
merge command can be used to determine whether the merge was
successful. If this is not set to true then the merge target file
timestamp is checked, and the merge is assumed to have been
successful if the file has been updated; otherwise, the user is
prompted to indicate the success of the merge.

mergetool.meld.hasOutput
Older versions of meld do not support the --output option. Git
will attempt to detect whether meld supports --output by
inspecting the output of meld --help. Configuring
mergetool.meld.hasOutput will make Git skip these checks and use
the configured value instead. Setting mergetool.meld.hasOutput to
true tells Git to unconditionally use the --output option, and
false avoids using --output.

mergetool.meld.useAutoMerge
When the --auto-merge is given, meld will merge all
non-conflicting parts automatically, highlight the conflicting
parts, and wait for user decision. Setting
mergetool.meld.useAutoMerge to true tells Git to unconditionally
use the --auto-merge option with meld. Setting this value to auto
makes git detect whether --auto-merge is supported and will only
use --auto-merge when available. A value of false avoids using
--auto-merge altogether, and is the default value.

mergetool.<vimdiff variant>.layout
Configure the split window layout for vimdiff's <variant>, which
is any of vimdiff, nvimdiff, gvimdiff. Upon launching git
mergetool with --tool=<variant> (or without --tool if merge.tool
is configured as <variant>), Git will consult
mergetool.<variant>.layout to determine the tool's layout. If the
variant-specific configuration is not available, vimdiff's is
used as fallback. If that too is not available, a default layout
with 4 windows will be used. To configure the layout, see the
BACKEND SPECIFIC HINTS section.

mergetool.hideResolved
During a merge, Git will automatically resolve as many conflicts
as possible and write the MERGED file containing conflict markers
around any conflicts that it cannot resolve; LOCAL and REMOTE
normally represent the versions of the file from before Git's
conflict resolution. This flag causes LOCAL and REMOTE to be
overwritten so that only the unresolved conflicts are presented
to the merge tool. Can be configured per-tool via the
mergetool.<tool>.hideResolved configuration variable. Defaults to
false.

mergetool.keepBackup
After performing a merge, the original file with conflict markers
can be saved as a file with a .orig extension. If this variable
is set to false then this file is not preserved. Defaults to true
(i.e. keep the backup files).

mergetool.keepTemporaries
When invoking a custom merge tool, Git uses a set of temporary
files to pass to the tool. If the tool returns an error and this
variable is set to true, then these temporary files will be
preserved; otherwise, they will be removed after the tool has
exited. Defaults to false.

mergetool.writeToTemp
Git writes temporary BASE, LOCAL, and REMOTE versions of
conflicting files in the worktree by default. Git will attempt to
use a temporary directory for these files when set true. Defaults
to false.

mergetool.prompt
Prompt before each invocation of the merge resolution program.

mergetool.guiDefault
Set true to use the merge.guitool by default (equivalent to
specifying the --gui argument), or auto to select merge.guitool
or merge.tool depending on the presence of a DISPLAY environment
variable value. The default is false, where the --gui argument
must be provided explicitly for the merge.guitool to be used.

TEMPORARY FILES

git mergetool creates *.orig backup files while resolving merges.
These are safe to remove once a file has been merged and its git
mergetool session has completed.

Setting the mergetool.keepBackup configuration variable to false
causes git mergetool to automatically remove the backup files as
files are successfully merged.

BACKEND SPECIFIC HINTS

vimdiff
Description

When specifying --tool=vimdiff in git mergetool Git will open Vim
with a 4 windows layout distributed in the following way:

------------------------------------------
| | | |
| LOCAL | BASE | REMOTE |
| | | |
------------------------------------------
| |
| MERGED |
| |
------------------------------------------

LOCAL, BASE and REMOTE are read-only buffers showing the contents
of the conflicting file in specific commits ("commit you are
merging into", "common ancestor commit" and "commit you are
merging from" respectively)

MERGED is a writable buffer where you have to resolve the
conflicts (using the other read-only buffers as a reference).
Once you are done, save and exit Vim as usual (:wq) or, if you
want to abort, exit using :cq.

Layout configuration

You can change the windows layout used by Vim by setting
configuration variable mergetool.vimdiff.layout which accepts a
string where the following separators have special meaning:

+o + is used to "open a new tab"

+o , is used to "open a new vertical split"

+o / is used to "open a new horizontal split"

+o @ is used to indicate the file containing the final version
after solving the conflicts. If not present, MERGED will be
used by default.

The precedence of the operators is as follows (you can use
parentheses to change it):

`@` > `+` > `/` > `,`

Let's see some examples to understand how it works:

+o layout = "(LOCAL,BASE,REMOTE)/MERGED"

This is exactly the same as the default layout we have
already seen.

Note that / has precedence over , and thus the parenthesis
are not needed in this case. The next layout definition is
equivalent:

layout = "LOCAL,BASE,REMOTE / MERGED"

+o layout = "LOCAL,MERGED,REMOTE"

If, for some reason, we are not interested in the BASE
buffer.

------------------------------------------
| | | |
| | | |
| LOCAL | MERGED | REMOTE |
| | | |
| | | |
------------------------------------------

+o layout = "MERGED"

Only the MERGED buffer will be shown. Note, however, that all
the other ones are still loaded in vim, and you can access
them with the "buffers" command.

------------------------------------------
| |
| |
| MERGED |
| |
| |
------------------------------------------

+o layout = "@LOCAL,REMOTE"

When MERGED is not present in the layout, you must "mark" one
of the buffers with an asterisk. That will become the buffer
you need to edit and save after resolving the conflicts.

------------------------------------------
| | |
| | |
| | |
| LOCAL | REMOTE |
| | |
| | |
| | |
------------------------------------------

+o layout = "LOCAL,BASE,REMOTE / MERGED + BASE,LOCAL +
BASE,REMOTE"

Three tabs will open: the first one is a copy of the default
layout, while the other two only show the differences between
(BASE and LOCAL) and (BASE and REMOTE) respectively.

------------------------------------------
| <TAB #1> | TAB #2 | TAB #3 | |
------------------------------------------
| | | |
| LOCAL | BASE | REMOTE |
| | | |
------------------------------------------
| |
| MERGED |
| |
------------------------------------------

------------------------------------------
| TAB #1 | <TAB #2> | TAB #3 | |
------------------------------------------
| | |
| | |
| | |
| BASE | LOCAL |
| | |
| | |
| | |
------------------------------------------

------------------------------------------
| TAB #1 | TAB #2 | <TAB #3> | |
------------------------------------------
| | |
| | |
| | |
| BASE | REMOTE |
| | |
| | |
| | |
------------------------------------------

+o layout = "LOCAL,BASE,REMOTE / MERGED + BASE,LOCAL +
BASE,REMOTE + (LOCAL/BASE/REMOTE),MERGED"

Same as the previous example, but adds a fourth tab with the
same information as the first tab, with a different layout.

---------------------------------------------
| TAB #1 | TAB #2 | TAB #3 | <TAB #4> |
---------------------------------------------
| LOCAL | |
|---------------------| |
| BASE | MERGED |
|---------------------| |
| REMOTE | |
---------------------------------------------

Note how in the third tab definition we need to use
parentheses to make , have precedence over /.

Variants

Instead of --tool=vimdiff, you can also use one of these other
variants:

+o --tool=gvimdiff, to open gVim instead of Vim.

+o --tool=nvimdiff, to open Neovim instead of Vim.

When using these variants, in order to specify a custom layout
you will have to set configuration variables
mergetool.gvimdiff.layout and mergetool.nvimdiff.layout instead
of mergetool.vimdiff.layout (though the latter will be used as
fallback if the variant-specific one is not set).

In addition, for backwards compatibility with previous Git
versions, you can also append 1, 2 or 3 to either vimdiff or any
of the variants (ex: vimdiff3, nvimdiff1, etc...) to use a
predefined layout. In other words, using --tool=[g,n,]vimdiffx is
the same as using --tool=[g,n,]vimdiff and setting configuration
variable mergetool.[g,n,]vimdiff.layout to...

+o x=1: "@LOCAL, REMOTE"

+o x=2: "LOCAL, MERGED, REMOTE"

+o x=3: "MERGED"

Example: using --tool=gvimdiff2 will open gvim with three columns
(LOCAL, MERGED and REMOTE).

GIT

Part of the git(1) suite

Git 2.48.1 2025-01-13 GIT-MERGETOOL(1)