The Diff Page

The Diff Page of the Add/Edit External Tool Dialog lets you configure the tool to be used for File Diffs.

2-Way File Diffing

This check box determines if this tool should be used for File Diffs.


This field contains the pathname of the executable that should be used for File Diffs.


On OS X, you can give the path to either the application bundle (the folder) or the name of the actual executable inside the application bundle (

Command Line Arguments

Since each external application seems to have its own unique argument ordering and command flags, we define the command line arguments using a template containing place-holder tokens. When DiffMerge is ready to launch the external application, it will substitute pathnames and labels into the template and build the actual command line.

DiffMerge defines the following substitution tokens for File Diffs:


The labels for the left and right files. In a DiffMerge File Diff Window, these labels are displayed above the panel; other applications may display them differently or not use them at all.

When DiffMerge is handing off the initial set of files received on the command line to an external tool, the values for these tokens come from the /title1 and /title2 arguments given to DiffMerge. Otherwise, they default to the pathnames of the corresponding files.


The pathnames of the corresponding files.

The Left and Right buttons are for your convenience and can be used to insert the corresponding token (with quotes) at the current insertion point into the text field.


It is highly recommended that you enclose each token in quotes so that whitespace in the titles and/or pathnames are properly received by the external application.