Toying with cal and date
Some date related tips I collected:
tips
#显示日历 $cal -3 #显示指定月,年的日历 $cal 9 1752 #这个星期五是几号? $date -d fri #今年圣诞礼拜几? $date --date='25 Dec' +%A #若干秒后的未来时刻时间计算 $date --date '2009-09-27 13:00:00 UTC 360000 seconds' #显示当前某地区时间时间(可用tzselect寻找时区) $TZ=':America/Los_Angeles' date #定时弹对话框 $echo "DISPLAY=$DISPLAY xmessage ALARM!!" | at "NOW + 30 minutes"

Discussion
Thanks for contributing. It's helped me understand the isuses.