Named pipe behavior: Flushing pipes

[Roger Oberholtzer]

How was this pipe made?


On Thu, 2003-12-11 at 03:38, Joel Hammer wrote:
> Using named pipes in bash:
> A book says that:
> echo My message > pipe
> will block if there is no program reading the pipe. On my system, the
> command doesn't block. You can use echo over and over to send things to
> the pipe.
> eg:
> 	echo line 1 > pipe
> 	echo line 2 > pipe
> 
> If you then type this:
> cat < pipe
> This blocks, even though the pipe is full of stuff.
> 
> If you echo one more thing to the pipe (in another terminal, leaving
> that blocked cat statement alone), like:
> 
> 	echo last line
> 
> everything in the pipe is printed out
> 
> line 1
> line 2
> last line
> 
> with that blocking cat command suddenly waking up.
> 
> SO:
> How can you make the cat command read the contents of the pipe
> without having to have an additional echo command to flush the pipe?
> 
> 
> Joel
> 
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