I can't seem to find any evidence that would place the origin of diff tool to the year 1972 (as stated on wikipedia). So where is any initial research paper on it, first release, source code?

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    Sorry - my PDP-11 dies last week so I can't any longer retrieve any of it's original UNIX source files to verify their time stamps. – Pieter Geerkens Jun 20 '18 at 17:18
  • What exactly are you challenging? I can assure you, from personal knowledge, that by summer 1981 the diff functionality was ubiquitous on both popular DEC operating systems: UNIX and VAX/VMS. – Pieter Geerkens Jun 20 '18 at 17:25
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    Not sure if we're looking a the same Wikipedia, but the page states development on it happened in the early 70's and first shipped with Unix in 1974. Where is the 1972 coming from? – Giter Jun 20 '18 at 17:32
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    As @Giter says, Wikipedia doesn't seem to say 1972. Please clarify if this was a typo, or if you meant something else. BTW, wiki also links to a 1976 paper on the program, where the developer remarked "in two year we have had brought to our attention only one jackpost" which seems to match the timeline given. – Semaphore Jun 20 '18 at 18:16
  • You might want to ask this over on StackOverflow or ServerFault, the former being more for coding/development questions. – SeligkeitIstInGott Jun 21 '18 at 1:57

The Unix Heritage Society shows that while diff's man page appeared in V6 (1975), its source code appeared in V5 (1974). The algorithm is described there as being "due to Harold Stone".

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