date "+%Y-%m-%d" 2013-02-19
date "+%H:%M:%S" 13:13:59
date "+%Y-%m-%d %H:%M:%S" 2013-02-19 13:14:19
date "+%Y_%m_%d %H:%M:%S" 2013_02_19 13:14:58
date -d today Tue Feb 19 13:10:38 CST 2013
date -d now Tue Feb 19 13:10:43 CST 2013
date -d tomorrow Wed Feb 20 13:11:06 CST 2013
date -d yesterday Mon Feb 18 13:11:58 CST 2013