man > git-mergetool(1)

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.layout
           The vimdiff backend uses this variable to control how its split windows appear. Applies
           even if you are using Neovim (nvim) or gVim (gvim) as the merge tool. See BACKEND
           SPECIFIC HINTS section for details.

       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:

           •   + 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
               asterisk. 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

           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...

           •   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).

GIT
       Part of the git(1) suite

Git 2.43.0                                   07/02/2025                             GIT-MERGETOOL(1)