On 4/10/19 6:46 AM, Eric Blake wrote: > On 4/9/19 11:03 PM, 方然 wrote: > >> [image: image.png] >> it is a same line! and if I delete some lines above and below this line >> then diff again it shows no difference as I expect. >> and not only this line all these lines in the first screenshot are same >> lines but show difference in diff. >> also use vimdiff to check. and show no difference in vimdiff. >> [image: image.png] > > Please don't ever send 9 megabytes of screenshots and sample files to a > mailing list (actually, I was a bit surprised that your images were > relatively small compared to the bulk of your log files, although it > would still have been a better use of bandwidth to just paste the text > from your window rather than capturing screenshots). You caused a lot of > unnecessary load on the mail server as it multiplied your message out to > every list recipient. Ideally, you should have minimized your problem > down to much smaller files - although the nature of the reported problem > in diff'ing large files may have indeed required the full log files to > reproduce (where trimming things would have made the problem disappear); > but even then, hosting your files externally and merely posting a URL in > the mail is more considerate when you would otherwise be sending more > than 100k to the list.
That said, when I use diff 3.6, I cannot reproduce the problem: 17172,17174c17172,17174 < 3 12 17 < 8 12 0 < 12 8 1 --- > 3 11 17 > 8 13 0 > 11 8 1 17186c17186 And the output that you reported, while annoying that it is not minimal, is not _wrong_ per se (applying the diff still results in the correct patched file, even if it required one line more effort than strictly required). The NEWS file mentions for 4.4: diff's default algorithm has been adjusted to output higher-quality results at somewhat greater computational cost, as CPUs have gotten faster since the algorithm was last tweaked in diffutils-2.6 (1993). so it could have been those fixes that improved diff in the meantime. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org
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