Date: Sat, 2 Dec 2000 17:13:45 -0500 From: Ryan Younce <ryan@manunkind.org> To: Garance A Drosihn <drosih@rpi.edu> Cc: Ryan Younce <ryan@manunkind.org>, Sue Blake <sue@welearn.com.au>, freebsd-questions@FreeBSD.ORG Subject: Re: "unbuffered" ? Message-ID: <20001202171345.C40048@cheshire.manunkind.org> In-Reply-To: <p04330103b64f1ff04070@[128.113.24.47]>; from drosih@rpi.edu on Sat, Dec 02, 2000 at 05:01:38PM -0500 References: <20001202224250.L377@welearn.com.au> <p04330106b64f0472caa4@[128.113.24.47]> <20001202152647.A40048@cheshire.manunkind.org> <p04330103b64f1ff04070@[128.113.24.47]>
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Thus spake Garance A Drosihn <drosih@rpi.edu>: > I tried 'ls' > vs 'ls | more' > > and ls still treated the second case as "not a tty". This is > understandable, as stdout to 'ls' is not a tty, it is the stdin > for 'more'. Right. Pipes are not considered terminals, they are considered files. isatty() will return false if the descriptor is a file. > I am not sure if that has any bearing on what you meant to say, > but given the context some people might think that you meant > that './myprog' could possibly fix the buffering problem by > calling isatty(). It can not. That 'more' could just as > easily be a 'grep', which means some lines might go to stdout, > and other lines would not. Once lines enter a pipe, there is > no way for the initial process to know whether those lines are > "really going to wind up" on the terminal. That wasn't my meaning at all. isatty() has nothing to do with setbuf(). As far as "ls | grep ...", STDOUT_FILENO within ls will still be considered a file, that is, not a terminal, regardless of what grep does with it's output. My original meaning was that it was very possible for the original process to determine whether its output was going to a file, or to a terminal. -- Ryan Younce / Registered Libertarian Voter | The notion of a 'record' is ryan@manunkind.org www.manunkind.org/~ryan/ | an obsolete remnant of the ICQ H:4433228 W:74390437 AIM:CheshireCoolCat | days of the 80-column card. Blitherings: http://cheshire.livejournal.com/ | -- Dennis M. Ritchie To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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