Nine Ways to Compare Files on Unix
Sometimes you want to know if some files are different. Sometimes you want to how they're different. Sometimes you might want to compare files that are compressed and sometimes you might want to compare executables. And, regardless of what you want to compare, you probably want to select the most convenient way to see those differences. The good news is that you have a lot more options than you probably imagine when you need to focus on file differences.
The command most likely to come to mind for this task is diff. The diff command will show you the differences between two text files or tell you if two binaries are different, but it also has quite a few very useful options.
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