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.

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

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

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 overrides a previous -g or --gui setting and reads the default merge tool will be read from the configured merge.tool variable.

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.

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

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.

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

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 assumed to have been successful if the file has been updated, otherwise the user is prompted to indicate the success of the merge.

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.

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.

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 overwriten 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.

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).

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.

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.

Prompt before each invocation of the merge resolution program.