Talk:Diff

message: This article mentions the longest common substring algorithm, but shouldn't it be subsequence? 129.241.124.103 (talk) 21:07, 10 July 2013 (UTC)
replies: text: Hmm, I'm rambling. It *is* subsequence, but for some reason I had the substring page up in another tab, and thought I clicked it from here. 129.241.124.103 (talk) 21:14, 10 July 2013 (UTC)
thread_title:  Subsequence vs. substring 

message: Could some one explain this in layman's terms?
:The diff algorithm is an implementation of the Longest-common subsequence problem, which is now linked to in Diff's "See also" section.
::I've added an example for clarity. I don't say it's a good (or realistic) example, but it will do for now. Without an example it's not clear what a diff really is, or looks like. --Shinobu 18:14, 28 Mar 2005 (UTC)
thread_title:  Layman's Terms 

message: I deleted Unix from the intro because there are diffs for every platform. The Unix heritage is discussed in the History section so I think that's okay. I removed the $-sign, because prompts look different on every system (even if one compares two Unixen). Apart from that, most texts illustrating a command to be entered don't display the prompt, because it might be confused with input that has to be entered by the user. Bye, Shinobu 18:12, 25 Apr 2005 (UTC)
thread_title:  Why I deleted Unix and the $-sign 

message: I think the page should have a little more about patch(1) - not the whole content of patch's page, but a short introduction and a link to the page; elsewhere than in the GNU advertisements or "See also" section. I might write something when I have time.
I've added a sentence to the  History section.
It could probably use mentioning in the  top section, I couldn't think of what. --132.198.104.164 17:49, 15 July 2005 (UTC)
thread_title:  Not enough said about patch(1) 

message: DiffNote parses the output of the GNU diff command 'diff -y' and it's a free web application. I originally listed it under Free software implementations, but someone moved it to External links because it's not software and it's a web app. I think it is a free software implementation, as in an implementation of software, and the description of Free software implementations fits it. I don't want to revert it back to the Free software implementations section because it's my web app and some people might say I shouldn't even have posted it in the first place, but if there's agreement here that it belongs under Free software implementations, I'll move it back. -Barry- 19:56, 25 February 2006 (UTC)
replies: text: I do not think it is an implementation as it is merely parsing diff's output, according to you. --maru  (talk) contribs 20:24, 25 February 2006 (UTC)
replies: text: I'm not sure whether parsing is the right word. DiffNote shows invisible characters as red dots, while 'GNU diff -y' renders them. If you use 'GNU diff -y' on a line that has a carriage return in the middle of the text, the CR will cause the text after the CR to show at the beginning of the line and the text that was at the beginning of the line in the file you were diffing won't be shown. In DiffNote, all text is shown and the CR is represented by a red dot (which will eventually be titled "ASCII 13" so you'll know exactly what it represents). The order of the lines in the output, and (essentially) the gutter markers are the same as in 'GNU diff -y' but other things, like the red dots, are different. -Barry- 20:41, 25 February 2006 (UTC)
thread_title:  Where to list DiffNote 

message: There seems to be increasing interest in the use of the patience diff algorithm, particularly for revision control. In particular, Codeville's precise merge algorithm (pcvd) employs it, and there has been interest in employing it for Bazaar-NG (see https://lists.ubuntu.com/archives/bazaar-ng/2005q4/005971.html, https://lists.ubuntu.com/archives/bazaar-ng/2006q2/010652.html). I've seen a few references (including Codeville's own documentation for pcvd at http://revctrl.org/PreciseCodevilleMerge) that point to the Patience sorting article.
* Longest-common subsequence problem doesn't mention Patience sorting.
* Patience sorting has a section "Algorithm for finding the longest increasing subsequence", but doesn't link to Longest-common subsequence problem.
* This article (diff) doesn't mention Patience sorting's applicability to diffing/patching.
I feel that this is something that wikipedia could treat better, but I'm not sure how to go about it.
— Daf 19:59, 21 May 2006 (UTC)
thread_title:  Patience diff 

message: the current diff -u example does not show at all that diff -u includes context above and below differences; for a moment, I had to wonder whether the article was showing an old version of diff -u that did not do context; but it's the example that does not allow any context as the differences are directly at both begin and end. --Habbie 01:13, 7 August 2006 (UTC)
replies: text: Yeah. We'll need a better example. I believe I'm the originator of the example - I at first used it as a stop-gap until something better was thought up, but eventually forgot about it and that's where we are now. Shinobu 06:50, 7 August 2006 (UTC)
thread_title:  unified diff example 

message: I've majorly overhauled the 'unified diff' section... please give comments.  AFAICT, the chunk size is redundant, as the patch program should be able to count the removed/added/contextual lines on its own.  Anyone know otherwise?  --=== Jez === 14:50, 7 September 2006 (UTC)
replies: text: If either chunk size doesn't correspond correctly with the number of actual such lines in the chunk, or any lines in the chunk are not preceded by +, -, or space, then the diff file is invalid.
I'm not so sure all the technical information on the unified diff format is required because some of your conclusions may not apply to all implementations of the patch utility.  Plus, its a little bit of original research, and may not be necessary in an encyclopedia.  You could try contributing it to the GNU diffutils manual (assuming your notes are based on GNU patch).  It also now duplicates the summary I derived from your contributions.  I'll try and fix that later. --71.161.218.87 00:51, 12 September 2006 (UTC)
thread_title:  unified diff 

message: Is there an error on the diff examples? Specifically, the sentence "things can be added after it." never appears in the given orig/new examples.
----
Good eye. You may be correct.  I've added it to the starting files.  I don't have time, now, but maybe we can verify the examples actually correspond verbatim with eachother.  (You can use diff to make sure). --71.161.214.168 21:52, 19 November 2006 (UTC)
replies: text: You diffed the diffs? — SheeEttin {T/C} 16:21, 25 July 2007 (UTC)
thread_title:  Example error? 

message: I think this article should mention interdiff, which is a program similar to diff that shows differences between diff files.  Apparently it's part of patchutils by Tim Waugh.  —Preceding unsigned comment added by 207.41.202.13 (talk) 16:01, 7 December 2007 (UTC)
thread_title:  interdiff 

message: Suggest to add after Daisy Diff HTML Diff
http://www.aaronsw.com/2002/diff/  —Preceding unsigned comment added by 88.149.243.200 (talk) 20:01, 15 March 2008 (UTC)
thread_title:  HTML Diff and Daisy Diff 

message: Is there a diff for WindowsXP?  —Preceding unsigned comment added by 71.131.2.120 (talk) 04:04, 9 June 2008 (UTC)
replies: text: Yes. See Comparison of file comparison tools. It also lists many other very similar tools that run on WindowsXP.  —Preceding unsigned comment added by 68.0.124.33 (talk) 04:14, 26 May 2009 (UTC)
thread_title:  Is there a diff for WindowsXP? 

message: The definition in the first paragraph is a little long.  This part seems to make it repetetive, "or the changes made to a current file by comparing it to a former version of the same file".  It would be better to have the first sentence be more concise by removing this, or making it a separate sentence.
I feel like it doesn't belong just because of its already assumed that diff compares multiple versions of the same file. --Ashawley (talk) 18:44, 14 August 2008 (UTC)
thread_title:  Definition 

message: Are you sure that "the chunk ranges specify the starting line number and the number of lines the change hunk applies to in the respective file"? By looking at the example's ('diff -c') range numbers I think that these numbers represent starting line number and ending line number (not the affected lines count). What do you think?  —Preceding unsigned comment added by 62.212.196.191 (talk) 01:38, 12 May 2009 (UTC)
thread_title:  Error about context format chunk ranges? 

message: I'm saddened to see so many links in the "External Links" section.  Just because something has the name "diff" included in it or does file comparison of some sort does not mean its relevant.  Looking over the revision history, most of these edits are made by one-time anonymous edits, and not be long-time editors.
There are nearly 20 links, currently.  Let's see what they are shall we?
; Altova DiffDog: is a "unique diff / merge utility" with a "visual interface" for "files, directories, and database tables" to "compare and merge text or source code files, synchronize directories, and compare database tables" and also "provides advanced XML-aware differencing and editing capabilities".  Interesting, and related, but doesn't have anything to do with the article. Removing.
; GNU Diff utilities: looks like classic unix diff as implemented by the GNU project, with source code to boot.  Good.
; Kdiff3: "compares or merges two or three text input files or directories" with a "graphical color display".  Interesting, and useful, and probably has source code, and maybe again this is how people will be working with Diffs some day (and become a mention in the article), but unfortunately, Wikipedia is not a crystal ball.  And even if it's useful to some, Wikipedia is not a link farm.  Kdiff3 could have an article of its own and be a "See also" mention from this article.  But that's just not the case, since it doesn't right now.  I'm not going to start  notable 3 years ago, either[]). Removing.
; DiffUtils for Windows: Seems to be a duplicate since it's just a port the GNU Diff utilities.  Windows is a dominant operating system, but every operating system can not be listed, and besides why should Windows receive special privilege?  Further, what if even more people port and package GNU diff utilities to Windows?  List those too?  Removed.
; Algorithm-Diff, TextDiff, java-diff and the JavaScript diff algorithms [5]: all seem to be libraries written in various programming languages with the name "diff" in them, and perhaps the core diff algorithm implemented--though I haven't verified them.  Their purpose is generic by design, but none of these describe an implementation of diff in toto. Removing.
; DaisyDiff: is a "Java library" that compares "HTML files" and "highlights added and removed words and annotates changes to the styling".   This is something that again isn't Diff, is related--especially since HTML files are also text files--but every domain that the diff concept is applied to can be listed--even the interesting one's.  Again it would be a valid "See also" section.  Removing.
; WinMerge: is in the "See also", so I'm not sure why this is here since there is already a WinMerge article.  Removed.
; Adobe Flex Diff: is another library implementation so removing per above. Removed.
; Meld: is the "Gnome GUI Diff tool".  Doesn't belong for the same reason as "Kdiff3". Removed.
; DeltaWalker: is a "file and directory comparison and synchronization" tool "for Linux".  It "lets you compare, edit, and merge files and synchronize directories, and "does so visually".  Doesn't belong for the same reason as "Kdiff3" and "Altove DiffDog". Removing.
; JSBlend: is a "web-based file comparison and merge tool" written "mostly in Javascript" that "relies on a Python or PHP backend" that in turn "relies mostly on the GNU DiffUtils toolset".  Sounds like it's really "mostly" GNU diffutils with a Web frontend.  Removing.
If the "External Links" section looks paltry by consequence, don't worry, the "References" section of the article has relevant links to make up for it.
So that leaves only one link.  I'm fine with not having anything, since the GNU diffutils link is not sacrosanct and the Diffutils manual is referenced in the article, already.
When you remove links that are irrelevant please refer to the Talk page in your edit. --Ashawley (talk) 05:20, 13 May 2009 (UTC)
thread_title:  External links 

message: The patch format discussion is missing the fact that if the "+++" line in the header refers to "/dev/null" rather than the file being edited, the patch program will interpret the hunk as file deletion (and will probably expect single hunk deleting all lines from the file. If "---" refers to "/dev/null", the patch program will interpret that as file creation (and will probably expect a single hunk adding all lines to the file). I am not sure about what will the patch program do if the "/dev/null" reference appears next to any other type of patch.  —Preceding unsigned comment added by Jozue (talk • contribs) 21:59, 30 August 2009 (UTC)
thread_title:  File addition and deletion to the patch format 

message: What is the justification for being in Category Formal Languages?
It was added to Revision as of 15:48, 14 May 2008.
I suggest deleting it. H.Marxen (talk) 20:16, 10 September 2009 (UTC)
thread_title:  Categories 

message: Shouldn't there be a separate section that is separate from the footnotes?  I made such an edit as , but it was reverted. --Ashawley (talk) 19:57, 12 October 2009 (UTC)
thread_title:  Separate "References" section 

message: This surprised me.  Transclusion is the inclusion of parts of documents into other documents,.  I don't see the relationship with diff, which doesn't do transclusion, but takes two text files and produce the list of differences.  Besides, Xanadu was a system to hold documents, not a utility; Xanadu was vaporware while diff was highly practical.  My proposal is to omit this paragraph entirely. Rp (talk) 08:38, 26 March 2010 (UTC)
replies: text: Done. Rp (talk) 12:35, 26 August 2010 (UTC)
thread_title:  Project Xanadu reference 

message: From the article: As a special case, unified diff expects to work with files that end in a newline. If either file does not, unified diff will emit the special line "\ No newline at end of file" after the modifications. The patch program should be aware of this.
Is the patch program aware of this (as it should be) or isn't it, and which is a problem that should be addressed?
--221.6.44.4 (talk) 05:31, 2 June 2010 (UTC)
thread_title:  The patch program '''should''' be aware of this. 

message: The source is interesting, but doesn't provide support for the statement to which it is attached, nor in fact to the previous statement (dismissing the one parenthetical remark which could be argued as relevant).  If it has something relevant to the topic, that should be mentioned. TEDickey (talk) 17:19, 1 February 2015 (UTC)
thread_title:  doug-reader source? 

message: If someone can provide a verifiable, published source for the early release history of Larry Wall's patch program, that might improve the topic.  Unsourced speculation can be removed without discussion TEDickey (talk) 12:49, 9 May 2015 (UTC)
thread_title:  early history of patch program 

message: A user is trying to create the false impression that the patch utility was not published before version 1.3, but this is verifyably wrong. Here is the head from version 1.2, retrieved from a usenet archive CD:
 #!/bin/sh
 #
 # [Laziness is the father of invention]
 #
 # Sorry the initial version was so sloppy, but I was just going on vacation
 # and couldn't bear not sending it out.
 #
 # Differences from version 1.1 to 1.2:
 #        Linted.
 #        Malloc bug fixed.
 #        Mktemp bug fixed.
 #        Will now work on files larger than 32767 for machines with small ints.
 #        Added a -R option for files with the new and old reversed.
 #
 # Happy patching!
 #
 # Larry Wall
 # {allegra,burdvax,cbosgd,hplabs,ihnp4,sdcsvax}!sdcrdcf!lwall
I hope this person rethinks his method for giving sources and learns to understand that a reliable source may exist anywhere - the net is just one of many information sources. 09:46, 11 May 2015 (UTC)
replies: text: If you have a source, then you can show where you found it.  You have not done so. Rather, the sole content of your comments is to accuse others of lying.  TEDickey (talk) 10:19, 11 May 2015 (UTC)
replies: text: You need to learn to correctly interpret sources and not to attack other people just because they did already found reliable sources. After some more research, patch-1.2 could even be found at google:  and after two more minutes this: . Schily (talk) 11:48, 11 May 2015 (UTC)

text: I did not add this to the article and you just verified again that you are always acting in a non-constructive way. Given the fact that I presented the correct source, you could have corrected the article instead of adding another non-constructive comment. Schily (talk) 10:35, 2 June 2015 (UTC)

text: Please stop to attack others... I of course provided the correct verification above with the link  I don't care whether you ignore this, but I care if you attack me with false claims. Schily (talk) 08:56, 3 June 2015 (UTC)

text: Don't misquote me! Schily (talk) 10:32, 4 June 2015 (UTC)
replies: text: I of course read your attack that was a result of not reading my original statement. Try to become a collaborative person instead of wasting other people's time. Schily (talk) 12:56, 8 June 2015 (UTC)
thread_title:  False claims by a user who frequently missinterprets sources. 

message: Of the new material I just added to the lead (symbol set size, Unicode issues), feel free to bend, spindle, fold, or mutilate as you wish.  I think both additions improve the scope of the article, but I haven't provided citations, and I probably didn't choose the best place.  This was purely a drive-by edit. — MaxEnt 20:44, 2 May 2017 (UTC)
replies: text: It doesn't belong in the lead (lede) unless it is a summary of sourced discussion within the topic itself. TEDickey (talk) 20:55, 2 May 2017 (UTC)
thread_title:  New material in lead 

message: http://lists.landley.net/pipermail/toybox-landley.net/2019-January/010049.html
 tools like svn or mercurial or git will create diffs that start like:
 
   +++ a/path/to/file
   --- b/path/to/file
--Cgbuff (talk) 06:11, 17 January 2019 (UTC)
thread_title:  Explain a/ vs. b/ path prefixes