It is used more in shell scripts:
In the linux environment to get the period a few days ago just use
date -d "x days ago" +%Y%m%d
Replace x with a number. If you need a positive number a few days ago , you can directly write a negative number if you want a few days later ;
date -d "x weeks ago" +%Y%m%d
Replace x with a number. If you need to write a positive number a few weeks ago , you can directly write a negative number if you want a date a few weeks later ;
date -d "x years ago" +%Y%m%d
Replace x with a number. If you need to write a positive number a few years ago , you can directly write a negative number if you want a date a few years later ;
See the following example:
[root@showsky ~]# date +%Y%m%d
20100107
Above is today's date 20100107
[root@showsky ~]# date -d "2 days ago" +%Y%m%d
20100105
The above is the date two days ago
[root@showsky ~]# date -d "4 days ago" +%Y%m%d
20100103
The above is the date four days ago
[root@showsky ~]# date -d "-1 days ago" +%Y%m%d
20100108 The
above is the date one day later
[root@showsky ~]# date -d "-2 days ago" +%Y%m%d
20100109
The above is the date two days ago
[root@showsky ~]# date -d "1 week ago" +%Y%m%d
20091231 The
above is the date one week ago
[root@showsky ~]# date -d "1 year ago" +%Y%m% d
20090107
above is the date one year ago