如何在CSV文件中将时间戳从MMDDYYYY更改为YYYYMMDD？

Question

我有一个csv文件读取类似：

"Name","Payment",...,"DATE"
"Mike","40",...,"12252012"
"Jack","55",...,"01162013"
...

该文件包含大约数千个这样的列表。并且有一些字段的值可能是8位数或更长的数字。有一点是肯定的：DATE字段是最后一列。

如何将其中的DATE列从MMDDYYYY更改为YYYYMMDD格式？

Korn Shell更好。

感谢。

Answer 1

修改：如果日期字段始终是连续的最后一个字段，则可以使用：

cat file.csv | perl -pe 's/(.*,")(\d{2})(\d{2})(\d{4})"/$1$4$2$3"/'

或

perl -p -i -e 's/(.*,")(\d{2})(\d{2})(\d{4})"/$1$4$2$3"/' file.csv

---

如果CSV只有一个八位或更多位的字段：

使用Perl：

cat file.csv | perl -pe 's/(\d\d)(\d\d)(\d\d\d\d)/$3$1$2/'

或更短（编辑文件）：

perl -p -i -e 's/(\d{2})(\d{2})(\d{4})/$3$1$2/' file.csv