Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.unix.programmer > #607

Re: Tail -f with filter question

Show all headers | View raw

On Tue, 17 May 2011 14:08:56 +0000, Scott Lurndal wrote:

>>I guess grep uses block buffering by default, so line buffering should
>>solve your problem
> 
> 
> stderr is line buffered by default.

On most Unices, stderr is initially *unbuffered*.

> stdout is line buffered if isatty() is true for the file descriptor
> associated with stdout, otherwise it is full buffered

This is the situation in practice for most Unices.

However, both the ISO C standard and POSIX have weaker requirements.

The ISO C standard (§7.19.3p7) says:

	As initially opened, the standard error stream is not fully
	buffered; the standard input and standard output streams are
	fully buffered if and only if the stream can be determined not
	to refer to an interactive device.

POSIX (§2.5) is practically identical:

	When opened, the standard error stream is not fully buffered;
	the standard input and standard output streams are fully
	buffered if and only if the stream can be determined not to
	refer to an interactive device.

<http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_05>

Back to comp.unix.programmer | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Tail -f  with filter question Matt Charles <mcharles48@gmail.com> - 2011-05-17 10:09 +0100
  Re: Tail -f  with filter question pk <pk@pk.invalid> - 2011-05-17 10:27 +0100
    Re: Tail -f  with filter question Mc <spam.mc@gmail.com> - 2011-05-17 10:55 +0100
      Re: Tail -f  with filter question pk <pk@pk.invalid> - 2011-05-17 11:04 +0100
  Re: Tail -f  with filter question Tobias Blass <tobiasblass@gmx.net> - 2011-05-17 09:59 +0000
    Re: Tail -f  with filter question scott@slp53.sl.home (Scott Lurndal) - 2011-05-17 14:08 +0000
      Re: Tail -f  with filter question Nobody <nobody@nowhere.com> - 2011-05-18 07:55 +0100
    Re: Tail -f  with filter question Geoff Clare <geoff@clare.See-My-Signature.invalid> - 2011-05-18 13:22 +0100
  Re: Tail -f  with filter question Damien Wyart <damien.wyart@free.fr> - 2011-05-17 16:36 +0200
    Re: Tail -f  with filter question James Waldby <not@valid.invalid> - 2011-05-17 18:22 +0000
      Re: Tail -f  with filter question Damien Wyart <damien.wyart@free.fr> - 2011-05-17 22:01 +0200

csiph-web