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From: mellman@ttrdd.UUCP
Newsgroups: comp.unix.questions
Subject: variables set in sh while loop don't get set?
Message-ID: <212@ttrdd.UUCP>
Date: Thu, 24-Sep-87 11:22:46 EDT
Article-I.D.: ttrdd.212
Posted: Thu Sep 24 11:22:46 1987
Date-Received: Sun, 27-Sep-87 22:04:08 EDT
Organization: AT&T, Skokie, IL
Lines: 81
Keywords: sh, ksh scripts, loops

When I set a variable in a while loop in a sh script, in some scripts
it doesn't seem to get set.  For example, a common thing is to do a

	pipeline | while read proc
	do

and then to test for some condition in a case statement.  Twice now, I
have written scripts where a variable set in the case loop (or anywhere
in the while loop, for that matter) won't have been changed from its
initial value after the while loop terminates.  Can anyone explain to me
why this is so.

For example, I have a little script that will log me off of my 630 terminal
by nohup-ing the login process - as long as only insignificant processes
are still running:

#
# This script will shutdown my account
#

PATH=$HOME/bin:/bin:/usr/bin:/usr/lbin
options="xd"
arglist=""
optlist=""

set -- `getopt $options $*`
if [ $? != 0 ]; then
	echo "Usage: $0 [$options]"
	exit -1
fi

for arg in $*; do
	case $arg in
	--)
		shift
		break
	;;
	-d)
		execute=2
		export execute
		shift
	;;
	-x)
		execute=1
		export execute
		shift
	;;
	esac
done

ps -u$LOGNAME | awk '{print $4}' | while read proc
do
	execute=3
	case $proc in
		sysmon | awk | ksh | ps | layers | COMMAND)
		;;
		"")
			echo '\007\007' defunct process?
			execute=0
			export execute
		;;
		*)
			echo '\007\007' $proc still running
			execute=0
			export execute
		;;
	esac
done

echo execute is $execute

if [ $? -eq 0 ]; then
	if [ ${execute:-0} -eq 1 ]; then
	    kill -1 ${fatherpid:-"fatherpid not set"}
	else
	    echo ${fatherpid:-"fatherpid not set"}
	fi
fi

But, at the echo, it can be seen that execute never got set during the
while loop.  It's driving me crazy.  Any help would be appreciated.