如何格式化CSV文件中的时间戳列？

Question

I'm triyng to format the first column of a CSV which is a unix timestamp in milliseconds to a format like this command:

date -d @$( echo "($line_date + 500) / 1000" | bc)

where $line_date is something like 1487693882310

And my file has this information:

1487152859086,,,,,,localhost.localdomain,ServerUpDown,ServerUp,,,,,,, ,,,,
1487613634268,,,,,,localhost.localdomain,ServerUpDown,ServerUp,,,,,,, ,,,,
1487614351573,,,,,,spadmin,logout,,,,,,,, ,,,,
1487614500536,,,,,,System,run,Perform Maintenance,,,,,,, ,,,,

I would like it to be like this:

mié feb 15 11:00:59 CET 2017,,,,,,localhost.localdomain,ServerUpDown,ServerUp,,,,,,, ,,,,
lun feb 20 19:00:34 CET 2017,,,,,,localhost.localdomain,ServerUpDown,ServerUp,,,,,,, ,,,,
lun feb 20 19:12:32 CET 2017,,,,,,spadmin,logout,,,,,,,, ,,,,
lun feb 20 19:15:01 CET 2017,,,,,,System,run,Perform Maintenance,,,,,,, ,,,,

I've tried this but it didn't work:

awk 'BEGIN{FS=OFS=","}{$1=`date -d @$( echo "($date_now + 500) / 1000" | bc)\`}1' file.csv

Any help will be much apreciated.

Thank you very much in advanced.

Kind regards.

Héctor

Answer 1

One way is to leave the CSV line intact and prepend it with the parsed timestamp as the first column.

Something like:

gawk -F, '{ printf "%s.%03u,",strftime("%Y-%m-%dT%H:%M:%S", $1/1000),$1%1000; print }' file.csv

Outputs:

2017-02-15T10:00:59.086,1487152859086,,,,,,localhost.localdomain,ServerUpDown,ServerUp,,,,,,, ,,,,
2017-02-20T18:00:34.268,1487613634268,,,,,,localhost.localdomain,ServerUpDown,ServerUp,,,,,,, ,,,,
2017-02-20T18:12:31.573,1487614351573,,,,,,spadmin,logout,,,,,,,, ,,,,
2017-02-20T18:15:00.536,1487614500536,,,,,,System,run,Perform Maintenance,,,,,,, ,,,,

Answer 2

Or you can rebuild the first field and then print the whole record like this:

echo 1487152859086,,,,,,localhost.localdomain,ServerUpDown,ServerUp,,,,,,, ,,,, | awk  'BEGIN{OFS=FS=","}{$1=strftime("%a %b %d %H:%M:%S %Z %Y", $1)}1'

You'll get this:

Fri Dec 13 14:45:52 CSTM 1901,,,,,,localhost.localdomain,ServerUpDown,ServerUp,,,,,,, ,,,,