LinuxQuestions.org - Remove every fourth line from CSV file?

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Remove every fourth line from CSV file?

Hi,

I have a large csv file which has data for every 15 minutes and I need only the hourly data. I would like to keep the first line, delete the next three lines, keep the fourth etc...

Sample of the orig data:

Code:

01/01/2009        0:00:57        sleep        84        8.4        -13.11

01/01/2009        0:16:12        sleep        84        8.4        -13.11

01/01/2009        0:31:27        sleep        84        8.4        -13.11

01/01/2009        0:46:42        sleep        84        8.4        -13.11

01/01/2009        1:01:57        sleep        84        8.4        -13.11

01/01/2009        1:17:12        sleep        84        8.4        -13.11

01/01/2009        1:32:27        sleep        84        8.4        -13.11

01/01/2009        1:47:42        sleep        81        8.1        -13.28

01/01/2009        2:02:57        sleep        81        8.1        -13.28

Desired output from above data:

Code:

01/01/2009        0:00:57        sleep        84        8.4        -13.11

01/01/2009        1:01:57        sleep        84        8.4        -13.11

01/01/2009        2:02:57        sleep        81        8.1        -13.28

A simple awk or bash command would suffice as I only need to perform this operation on 1 or 2 files.

Any help is appreciated!
Thanks.

Code:

sed -n '1~4p' input

Prints every 4th line. Add -i to make the changes permanent.

See http://www-h.eng.cam.ac.uk/help/tpl/unix/sed.html

Works like a charm, exactly what I needed! Thank-you so much!

No problem :)

If you want to change the starting line, change the 1 to the line you want to start from. Likewise change 4 to 8 if you want it every 2 hours instead.

I'm sure there is an awk solution too, but if this works, so much the better. It's not exactly the longest command ever, either :)