sed_loop_test

#!/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