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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | CONFIGURATION | TEMPORARY FILES | BACKEND SPECIFIC HINTS | GIT | COLOPHON |
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GIT-MERGETOOL(1) Git Manual GIT-MERGETOOL(1)
git-mergetool - Run merge conflict resolution tools to resolve
merge conflicts
git mergetool [--tool=<tool>] [-y | --[no-]prompt] [<file>...]
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.
-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.
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.<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 are 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.
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.
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:
• + is used to "open a new tab"
• , is used to "open a new vertical split"
• / is used to "open a new horizontal split"
• @ 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:
• 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"
• layout = "LOCAL,MERGED,REMOTE"
If, for some reason, we are not interested in the BASE
buffer.
------------------------------------------
| | | |
| | | |
| LOCAL | MERGED | REMOTE |
| | | |
| | | |
------------------------------------------
• 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 |
| |
| |
------------------------------------------
• layout = "@LOCAL,REMOTE"
When MERGED is not present in the layout, you must "mark"
one of the buffers with an arobase (@). That will become
the buffer you need to edit and save after resolving the
conflicts.
------------------------------------------
| | |
| | |
| | |
| LOCAL | REMOTE |
| | |
| | |
| | |
------------------------------------------
• 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 |
| | |
| | |
| | |
------------------------------------------
• 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:
• --tool=gvimdiff, to open gVim instead of Vim.
• --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]vimdiff<x> is the same as using
--tool=[g|n]vimdiff and setting configuration variable
mergetool.[g|n]vimdiff.layout to...
• <x>=1: "@LOCAL, REMOTE"
• <x>=2: "LOCAL, MERGED, REMOTE"
• <x>=3: "MERGED"
Example: using --tool=gvimdiff2 will open gvim with three
columns (LOCAL, MERGED and REMOTE).
Part of the git(1) suite
This page is part of the git (Git distributed version control
system) project. Information about the project can be found at
⟨http://git-scm.com/⟩. If you have a bug report for this manual
page, see ⟨http://git-scm.com/community⟩. This page was obtained
from the project's upstream Git repository
⟨https://github.com/git/git.git⟩ on 2025-08-11. (At that time,
the date of the most recent commit that was found in the
repository was 2025-08-07.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
Git 2.51.0.rc1 2025-08-07 GIT-MERGETOOL(1)
Pages that refer to this page: git(1), git-config(1), git-difftool(1), git-gui(1), git-merge(1), stg(1)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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