Change format of a field using awk

Friday, December 28, 2012 awk 0 Comments

I have a very large file with more than 500,000 lines of dated events.The first field contains the date/time in the following format:

20120727-files.files:20120727090044

Where the first 8 numbers represent yyyymmdd. The last set of numbers represent yyyy/mm/dd/hh:mm:ss I would like to change the value of the first field to:

YYYY-MM-DD HH:MM:SS

solution:

awk -F":" '{
           print substr($2,0,4)"-"substr($2,5,2)"-"
                 substr($2,7,2)" "substr($2,9,2)":"
                 substr($2,11,2)":"substr($2,13,2)
           }' your_file