Date: Sun, 29 Aug 2010 16:54:44 -0400 From: jhell <jhell@DataIX.net> To: Alexander Best <arundel@freebsd.org> Cc: Anonymous <swell.k@gmail.com>, freebsd-hackers@freebsd.org Subject: Re: tiny patch to prevent head from closing pipes Message-ID: <4C7AC914.1080804@DataIX.net> In-Reply-To: <20100828160129.GA88842@freebsd.org> References: <20100828141625.GA69240@freebsd.org> <86aao694tm.fsf@gmail.com> <20100828160129.GA88842@freebsd.org>
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On 08/28/2010 12:01, Alexander Best wrote: > On Sat Aug 28 10, Anonymous wrote: >> Alexander Best <arundel@freebsd.org> writes: >> >>> hi there, >>> >>> i just had subversion complain about a broken pipe while piping its output >>> through awk straight to head [1]. i decided to add a switch to head which will >>> tell it to never close a pipe unless the input has stopped [2]. >> >> You can do same with sh(1), e.g. >> >> $ svn log | (IFS=; while read li; do [ $((i+=1)) -le 10 ] && echo "$li"; done) >> >> versus >> >> $ svn log | (IFS=; while read li && [ $((i+=1)) -le 10 ]; do echo "$li"; done) >> ... >> svn: Write error: Broken pipe >> >> >> But I think subversion should >> >>> there's probably a much more efficient way of discarding the input without >>> closing the pipe unless the input ceased. it's just a 5 minute hack in order to >>> see if people find the idea useful or not. ;) >> >> Can you give an example of usefulness that does not involve subversion? > > no, but this should be valid for all applications which return an error if the > pipe gets closed by the receiving end. > > of course it's possible to implement the features to head i added in form of a > sh(1) script. i understand that your point is, that there is already a way of > keeping the pipe open and that the unix philosophy states that no two programs > should share the same functionality. > > on the other hand you don't really need head and tail at all then, because > their functionality could also be implemented in form of a script. ;) i hope > you get my point. > > cheers. > alex > No offense but patching this would be honoring bad scripting and encouraging such things to happen more often. If you catch my drift. Regards, -- jhell,v
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