NetNews Usenet Archive 1992 #30/NN_1992_30.iso/spool/comp/unix/shell/5084

Text File | 1992-12-15 | 1.6 KB | 50 lines

Newsgroups: comp.unix.shell
Path: sparky!uunet!munnari.oz.au!bruce.cs.monash.edu.au!merlin!cerberus!cerberus.bhpese.oz.au!Sm
From: [e-mail] (Scott Merrilees)
Subject: Re: rsh terminates while loop
Organization: BHP, Newcastle, Australia
Date: Wed, 16 Dec 1992 01:57:18 GMT
Message-ID: <[e-mail]>
References: <[e-mail]>
Sender: [e-mail] (News System)
Lines: 38

[e-mail] (william E Davidsen) writes:


>  It appears that the rsh does /something/ which wipes out the stdin of
>the while loop. What I would like to understand is what's happening (I
>already have an ugly but functional workaround).

>$ cat y.tmp
>qx1 -a
>qx2 -a
>danqx -l
>$ cat x.tmp
>#!/bin/sh
>while read host flags
>do
> result=`rsh $host uname $flags`
> echo "$host: $result"
>done
>$ ./x.tmp < y.tmp
>qx1: qx1
>$

>Note that after reading a single line from the file the while loop ends.
>Any command other than rsh does not cause this, and if you use ksh you
>get an illegal IOCTL fault (under SunOS).

use 'rsh -n' if it works for you, otherwise use 'rsh </dev/null'.

What happens is that the local rsh can't know when the remote process need
input, so it gobbles up stdin and passes it to the remote process, thus
using all your input.  If the remote process doesn't use all or any of the
input, then it is lost, because it isn't passed back and reinserted into
stdin.

Sm
--
Scott Merrilees, BHP Information Technology, Newcastle, Australia
Internet: [e-mail]   Phone: [phone]   Fax: ... 2165