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How to delete specific lines (2n+3 line, n=0,1,2...296) in a file?

 
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# 1  
Old 02-09-2013
How to delete specific lines (2n+3 line, n=0,1,2...296) in a file?
Dear everyone,
I have a file with 900 lines (there is only numbers in one line, no string),
I only need the lines 2+3n (n=0,1...296), i.e line 2, 5, 8, 11...888.
I tried google but only the results such as how to delete all the odd lines or all the even lines with 'awk' command.
Thanks in advance.
# 2  
Old 02-09-2013
Assuming that you need those particular lines to be printed:
Code:
awk '!((NR-2)%3)' file

These 2 Users Gave Thanks to elixir_sinari For This Post:
alister phamnu
# 3  
Old 02-09-2013
Quote:
Originally Posted by elixir_sinari
Assuming that you need those particular lines to be printed:
Code:
awk '!((NR-2)%3)' file

You are great!!!
# 4  
Old 02-09-2013
Code:
$ sed -n '2~3p' file
2
5
8

Not sure this is POSIX compliant, though...
# 5  
Old 02-09-2013
Quote:
Originally Posted by RudiC
Code:
$ sed -n '2~3p' file

Not sure this is POSIX compliant, though...
Not sure either, but the AIX sed doesn't understand it. I suppose it is a GNU extension.

I hope this helps.

bakunin
 
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