From: "Bart Schaefer" <schaefer@candle.brasslantern.com>
To: zsh-workers@sunsite.auc.dk
Subject: Redirection with multiple coprocs
Date: Tue, 3 Oct 2000 16:42:36 +0000 [thread overview]
Message-ID: <1001003164236.ZM21637@candle.brasslantern.com> (raw)
About a year ago, I wrote:
} coproc tr a-z A-Z
} exec 5>&p ;: descriptor 5 is now the input of tr
} exec 6<&p ;: descriptor 6 is now the output of tr
} coproc sed s/DOG/CAT/ 5>&-
} exec 7>&p ;: descriptor 7 is now the input of sed
} exec 8<&p ;: descriptor 8 is now the output of sed
} coproc exit ;: close p
} cat <&6 >&7 5>&- 7>&- & : tr is now connected to sed
} exec 6<&- 7>&- ;: close shell copies of descriptors
This can of course be shortened as:
coproc tr a-z A-Z
exec 5>&p 6<&p
coproc sed s/DOG/CAT/ <&6 5>&-
exec 6<&- 8<&p
coproc exit
It seems to me that the following should be an even shorter way (or at
least, using fewer descriptors):
coproc tr a-z A-Z
exec 5>&p
coproc sed s/DOG/CAT/ <&p
exec 8<&p
coproc exit
But it doesn't work, because the old coproc descriptors are closed before
the redirection to the new coproc is processed, so sed gets a closed stdin.
How does ksh handle redirecting the coproc descriptors to a new coproc?
--
Bart Schaefer Brass Lantern Enterprises
http://www.well.com/user/barts http://www.brasslantern.com
Zsh: http://www.zsh.org | PHPerl Project: http://phperl.sourceforge.net
reply other threads:[~2000-10-03 16:43 UTC|newest]
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