PG=lifo
H='
==========
lifo new_file old_file
==========
maintains an archive (old_file) that has new_file at
its head.
==========
'
case $1 in 
    -h|help|hint)   clear;echo "$H";exit 0;;
esac
T=/usr/tmp/$PG$$
trap '/bin/rm -f $T;exit' 0 1 2 3 4 14
if test -s $2
then
X='cp $2 $T;cp $1 $2;cat $T >> $2'
else
X='cp $1 $2'
fi
eval $X