#!/bin/sh/
WKDIR=$(realpath ~)
sed_script='${WKDIR}/test_sed_script'
cmd_script='${WKDIR}/cmd_sed_script'
local fifo="/var/tmp/getoptions.$$.$RANDOM" 
mkfifo $fifo || { 
  echo "$(basename $0): getoptions: Error creating named pipe. Exiting." >&2 exit 2 } 
( sed -f "$sed_script" "$fifo" >$fifo ; rm -f $fifo ) & 
trap 'echo Received SIGPIPE >&2' SIGPIPE 
globalvar= 
while read; do 
# first loop : 
done < <($cmd_script) 
## do something with globalvar 
#while read; do 
#  #second loop : 
#done <$fifo \trap - SIGPIPE