: !/bin/sh
# convert MMYYYY ($1) to MMM$2YYYY (stdout)
# if no $2 defaults to " "
awk -v "MMYYYY=$1" -v "sep=$2" '
BEGIN {
	monthstr[1]  = "Jan";
	monthstr[2]  = "Feb";
	monthstr[3]  = "Mar";
	monthstr[4]  = "Apr";
	monthstr[5]  = "May";
	monthstr[6]  = "Jun";
	monthstr[7]  = "Jul";
	monthstr[8]  = "Aug";
	monthstr[9]  = "Sep";
	monthstr[10] = "Oct";
	monthstr[11] = "Nov";
	monthstr[12] = "Dec";
	billmm = 0 + substr(MMYYYY,1,2)
	billyyyy = 0 + substr(MMYYYY,3,4)
	if ( sep != "" )
		sepchar = substr(sep,1,1)
	else
		sepchar = " "
	billperiod = monthstr[billmm] sepchar billyyyy
	print billperiod
	exit
}'
exit 0