Date: Sat, 23 May 2020 14:47:32 +0300 From: Yuri Pankov <ypankov@fastmail.com> To: Fehmi Noyan ISI <fnoyanisi@yahoo.com> Cc: freebsd-hackers@freebsd.org Subject: Re: diff(1) -N behaviour - Bug 233402 Message-ID: <efe1c596-f99e-5e1e-3c1a-0e4af38e3464@fastmail.com> In-Reply-To: <4ADEBC26-0F93-45C1-B775-E6E33E95FDC1@yahoo.com> References: <B380BAF4-2343-4A22-A26D-13437ECC00C2.ref@yahoo.com> <B380BAF4-2343-4A22-A26D-13437ECC00C2@yahoo.com> <94a82a22-b5c9-b797-30cc-0242f6da1c8a@fastmail.com> <4ADEBC26-0F93-45C1-B775-E6E33E95FDC1@yahoo.com>
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Fehmi Noyan ISI via freebsd-hackers wrote: > > >> On 23/05/2020, at 11:21 PM, Yuri Pankov <ypankov@fastmail.com> wrote: >> >> Fehmi Noyan ISI via freebsd-hackers wrote: >>> Hiya >>> Apparently, after we switched from GNU diff to BSD diff, the -N flag no longer assumes absent files as empty. >>> There is a bug report about GNU diff compatibility but when I look at diff(1) man page, I see that not treating absent files as empty is intentional rather than a missing functionality. >>> If this is not the case, I can work on patch to match to GNU diff behaviour, otherwise, this bug report can be closed I think. >>> What’s your take on this? >>> -N --new-file >>> If a file is found in only one directory, act as if it was found >>> in the other directory too but was of zero size. >>> man for GNU diff >>> -N, --new-file >>> treat absent files as empty >> >> I think both descriptions say the same, i.e. "zero size" == "empty”? > > Maybe it’s my interpretation, but if you do not supply the second argument to diff(1), it complains > $ echo “test” > a.txt > $ diff -N a.txt nofile > diff: nofile: No such file or directory > $ > > GNU diff assumes an empty file for the missing second file and makes the comparison > $ echo “test” > a.txt > $ diff -N a.txt nofile > 1d0 > < test > $ I must admit that I never used -N without -r, so it's probably the only case that needs fixing? $ mkdir a b $ echo bar > a/foo $ diff -ruN a b diff -ruN a/foo b/foo --- a/foo 2020-05-23 14:44:34.525932000 +0300 +++ b/foo 1970-01-01 03:00:00.000000000 +0300 @@ -1 +0,0 @@ -bar
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