sed/awk remove characters in specific positions after match

Question

I'm looking for an awk or sed solution, I'm not a genius with either. I have read all of the suggestions that came up when I started typing this up.

I have a file with lines of data:

name
 thisdate=Sep  2 23:59:59 2022 GMT
name
 thisdate=Sep 15 23:59:59 2022 GMT

The names and dates/times are all different, the day numbers are always in the same place and always take up the same number of characters (2), the hours/min/secs are all always in the same position on the line and its not every line, thisdate is always a date in the future, and there are no blank lines.

I am trying to remove the time from those date lines by trying to key off  thisdate= (that's a space in front of thisdate) and then deleting characters in positions 18-26 (if I counted right)

I've tried a couple things but have been mostly searching for something that fits my needs to point me in the right direction

  952  sed 's/^\(.\{18\}\)\(.\{26\}\)/\1/' file  <--this may not have worked as I didn't key on a match?
  958  sed -i 's/thisdate=(.{11})18/\26/' file
  959  sed -i 's/thisdate=(.{10})17/\25/' file

I'm sure I'm missing something but if someone could point me in the right direction I'd be grateful!

Answer 1

It looks like it should be enough with just deleting 9 characters after the 6th character after  thisdate=:

sed 's/^\( thisdate=.\{6\}\).\{9\}/\1/' file

For the given data, this would generate

name
 thisdate=Sep  2 2022 GMT
name
 thisdate=Sep 15 2022 GMT