DESCRIPTION
-----------
-Use 'git mergetool' to run one of several merge utilities to resolve
+Use `git mergetool` to run one of several merge utilities to resolve
merge conflicts. It is typically run after linkgit:git-merge[1].
If one or more <file> parameters are given, the merge tool program will
be run to resolve differences on each file. If no <file> names are
-specified, 'git mergetool' will run the merge tool program on every file
+specified, `git mergetool` will run the merge tool program on every file
with merge conflicts.
OPTIONS
Valid merge tools are:
kdiff3, tkdiff, meld, xxdiff, emerge, vimdiff, gvimdiff, ecmerge, and opendiff
+
-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'
+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
+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.
+`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 configration
+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.
Author
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