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From: ggm@brolga.cc.uq.oz.au (George Michaelson)
Newsgroups: comp.unix.shell
Subject: read in /bin/sh appears to be VERY cpu costly.
Message-ID: <1991May8.013013.29811@brolga.cc.uq.oz.au>
Date: 8 May 91 01:30:13 GMT
Organization: Prentice Computer Centre, The University of Queensland, Australia.
Lines: 29

I have written a very crude shellscript to do while loops over a read
command. This is to permit a user attached to a terminal that cannot
do control characters (!) to get access to unix and do some useful stuff
with MH and editors.

I have just found out she incurred around 300 seconds of CPU time on a
sun 4 in 1 login session.

simple tests using time on a shellscript of:

	while 1
	do
		read INP
		echo $INP
	done

seem to suggest that read is incredibly expensive on the CPU.

Is this true, and is there any "cheaper" way to do interactive input
from a terminal within shellscripts?

Is this a "feature" in SunOS 4.1.1 /bin/sh?

	-George
-- 
	G.Michaelson
Internet: G.Michaelson@cc.uq.oz.au                     Phone: +61 7 365 4079
  Postal: George Michaelson, the Prentice Centre,
          The University of Queensland, St Lucia, QLD Australia 4072.