Question

I have a file with records having timestamp fields that include GMT offset. I want to use the sed command to replace the value on the record to a regular timestamp (without GMT offset).

For example:

`$date -d '2012/11/01 00:50:22 -0800' '+%Y-%m-%d %H:%M:%S'`

returns this value which is what I am looking to do:

2012-11-01 01:50:22

Except I want to perform that operation on every line of this file and apply the date command to the timestamp value. Here is a sample record:

"SB","6GV96644X48128125","","","","T0006",2012/10/03 13:08:43 -0700,"NJ"

Here is my code:

head -1 myfile | sed 's/,[0-9: /\-]\{25\},/,'"`date -d \1 '+%Y-%m-%d %H:%M:%S'`"',/

which doesn’t work: it just ignores \1 and replaces the matched pattern with today’s date:

"SB","6GV96644X48128125","","","","T0006",2012-11-14 01:00:00,"NJ"

I hoped that \1 would result in the matched patterns be passed to the date function and return a regular timestamp value (as in the example I provided above showing how the date functions applies the GMT offset and returns a regular stimestamp string) and would replace the old value on the record.

Answer 1

I would use awk instead. For example:

awk '{cmd="date -d \""$7"\" \"+%Y-%m-%d %H:%M:%S\"";
    cmd | getline k; $7=k; print}' FS=, OFS=, myFile

This will replace the 7th field with the results of running the date command on the original contents of the 7th field.