This tool is fine for a quick glance at the differences, but what if you want to see what exactly has changed between the two files, line by line? To see such information, you need to install an external diff viewer application. There are quite a few of such applications available on the web, and the basic way of using them is the same: you need to specify the two files to compare, and the diff viewer would display them side by side and show the differences in some way.

One of such tools is DiffMerge published by SourceGear, LLC. It's a free download, no payment is required to use this tool (at least that was the case at the time of this writing.) To download DiffMerge, first determine whether your Windows version is 32- or 64-bit. Then, go to the DiffMerge download page and select the appropriate version, 32- or 64-bit, to match your version of Windows. Download and save the file to your hard drive. Finally, run the setup file to install DiffMerge on your computer.

Next step is to integrate DiffMerge software with AB Commander, to be able to quickly use it to display the differences between the two selected files, without the need to specify them separately using the DiffMerge file selection interface. To do that, we need to set up DiffMerge as the external file comparer within AB Commander. Choose View - Options from the menu of AB Commander, select the Tools tab, select File Comparer in the dropdown box, and press the Options button next to External. When the Options for External File Comparer window opens, specify the path to the DiffMerge application in the Path area, such as:

"C:\Program Files\SourceGear\Common\DiffMerge\sgdm.exe"

(You can determine this path by, for example, looking into the properties of the shortcut that DiffMerge installs on your Windows desktop.)

Also, enter the following text in the Command line area:

"%1" "%2"

Why such a command line? It will be used by AB Commander to pass the information about the selected files to DiffMerge when you launch it from within AB Commander: %1 will be replaced with the path of the first selected file, %2 with the path of the second selected file, and they both will be enclosed in the double quotes, to account for the possibility of the presence of the space characters in their file names:

That's all that it takes to integrate DiffMerge with AB Commander. From now on, when you want to examine the differences between two text files in detail, select them in AB Commander, and choose Ctrl+Shift+E (or choose Tools - Compare Files - Alternative File Comparer from the menu) and DiffMerge will be launched for you:

The differences between two files displayed by DiffMerge (click to enlarge).

One final note: such file comparison only works with the plain text files, such as the files created with Windows Notepad, or with the Quick Editor of AB Commander. If you want to compare, say, two Microsoft Word files, you should use the built-in revision history viewer that Microsoft Word provides and that's specifically designed for the Word files.

Happy file managing!

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