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#!/bin/sh
#
# The scripts cur_param and next_param allow their callers to cycle through
# circular lists of parameters. Both scripts take two parameters, a directory
# name and a counter name.
#
# The idea is that the user sets up the file $dir/list.$counter to contain
# a list of parameters, one per line. Each time the user calls cur_param,
# they get back as the output of the script the current parameter (initially
# the first). Each time the user calls next_param, the scripts' notion of
# the current parameter is set to the parameter on the next line of the file,
# or, if there are none left, back to the parameter on the first line.
# next_param has only this side-effect; it does not output anything.
#
# Both scripts exit with a non-zero status in case of internal error.
usage="next_param dir counter"
if test $# != 2
then
echo $usage
exit 1
fi
dir=$1
counter=$2
if test ! -f $dir/next.$counter
then
echo 0 > $dir/next.$counter
fi
if test -s $dir/list.$counter
then
prev=`cat $dir/next.$counter`
next=`expr $prev + 1`
length=`wc -l $dir/list.$counter`
if test "$next" -gt "$length"
then
next=1
fi
echo "$next" > $dir/next.$counter
else
echo "$dir/list.$counter doesn't exist or is empty"
exit 1
fi
exit 0
|
