3.4.1 Comparing Three Different Files (diff3)

If you have three versions of a file that you want to compare at once, use the diff3 command as follows:

$ diff3 file1 file2 file3

diff3 compares three versions of a file and publishes disagreeing ranges of text flagged with these codes:

==== all three files differ

====1 file1 is different

====2 file2 is different

====3 file3 is different