diff

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diff
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This article is about the file comparison utility. For other uses, see DIFF (disambiguation).
"Diffs" redirects here. For the American punk rock group, see The Diffs.
In computing, diff is a file comparison utility that outputs the differences between two files. It is typically used to show the changes between one version of a file and a former version of the same file. Diff displays the changes made per line for text files. Modern implementations also support binary files.[1] The output is called a diff or a patch since the output can be applied with the Unix program patch. The output of similar file comparison utilities are also called a "diff". Like the use of the word "grep" for describing the act of searching, the word diff is used in jargon as a verb for calculating any difference.

Contents
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1 History
2 Algorithm
3 Usage
4 Variations
4.1 Edit script
4.2 Context format
4.3 Unified format
4.4 Others
5 Free file comparison tools
6 See also
7 Notes
8 External links