使用bash脚本格式化csv中的日期列

Question

I have multiple comma separated files in a folder. Each CSV file looks like following:

"Column1","Date","Column2"
"fdfsd","20151023","rwer"
"fsdsf","20151023","jjfg"
.
.

I need to modify the 2nd Date column to display the date in this format "10/14/2015" or "2015-10-14".

Please can someone help me with this?

Thanks

This is what i have tried:

cat test.csv | while read line ; do echo $line\;$(date -d "%Y%m%d" "+ YYYY/MM/DD") ; done

usage: date [-jnu] [-d dst] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS]] ... [-f fmt date | [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format] "Column1","Date","Column2";

usage: date [-jnu] [-d dst] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS]] ... [-f fmt date | [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format] "fdfsd","20151023","rwer";

usage: date [-jnu] [-d dst] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS]] ... [-f fmt date | [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format] "fsdsf","20151023","jjfg";

Answer 1

由于您只需要在日期中插入连字符，因此这是一个字符串操作问题，而不是日期操作问题：

sed -i.bak -re 's/([0-9]{4})([0-9]{2})([0-9]{2})/\1-\2-\3/' *.csv

Answer 2

You can use this awk to reformat a given date string:

awk 'BEGIN{FS=OFS=","} NR>1{cmd = "date -d \"" $2 "\" \"+%Y-%m-%d\"";
       cmd | getline out; $2=out; close("uuidgen")} 1' file
"Column1","Date","Column2"
"fdfsd",2015-10-23,"rwer"
"fsdsf",2015-10-14,"jjfg"

Answer 3

Python has a very robust csv module.

You can do:

$ python -c '
import csv
import datetime
import fileinput

def line_out(line): 
    print ",".join(["\"{}\"".format(e) for e in line])

csv_data=csv.reader(fileinput.input())
line_out(next(csv_data))
for line in csv_data:
    line[1]=datetime.datetime.strptime(line[1], "%Y%m%d").date().isoformat()
    line_out(line)' file

Prints:

"Column1","Date","Column2"
"fdfsd","2015-10-23","rwer"
"fsdsf","2015-10-23","jjfg"