shell 日期加减运算

比如今日是2012-04-22
$ date -d "+1 day" +%Y-%m-%d
2012-04-23

$ date -d "-1 day" +%Y-%m-%d
2012-04-21

$ date -d "2012-04-10 -1 day " +%Y-%m-%d
2012-04-09

$ date -d "2012-04-10 +1 day " +%Y-%m-%d
2012-04-11

$ date -d "-1 week " +%Y-%m-%d
2012-04-15

$ date -d "+1 week " +%Y-%m-%d
2012-04-29

$ date -d "+1 month " +%Y-%m-%d
2012-05-22

$ date -d "-1 month " +%Y-%m-%d
2012-03-22

$ date -d "-1 year " +%Y-%m-%d
2011-04-22

$ date -d "+1 year " +%Y-%m-%d
2013-04-22

文章转自于：http://zgysc.blog.163.com/blog/static/42370520201383094911499/