指定月の月末日を取得する

#BASH

YEAR=2014
MONTH=12
date -d${MONTH}/01/${YEAR}-1days+1month '+%Y%m%d'

結果

20141231

#PYTHON

from datetime import date, timedelta
from dateutil.relativedelta import relativedelta
year = 2014
month = 12
print date(year, month , 1) + relativedelta(months=1) + timedelta(days=-1)

結果

2014-12-31