Log file - Delete lines

Shell Programming and Scripting
1

Hello,

I tried to search on the site a way to delete lines on log files but I didn't find what I am looking for... I hope someone will be able to help me.

I do not know how to explain this, so I will do my best.

I have a log file and I want to delete all second lines.

Example :

file master_1 has been read ok
reading ok
file master_2 has been read ok
reading ok
file master_3 was not read
reading nok

Here is what I am looking for

file master_1 has been read ok
file master_2 has been read ok
file master_3 was not read

As it's just an exemple, the idea is to delete easly all lines multiple of 2. So delete line pair 2;4;6 and so on ....

I can't use

grep -v

has the retrun code has multiple values ..

Thanks for your help ...

2 
 
$ nawk '{if(NR%2==1)print $0}' logFileName
file master_1 has been read ok
file master_2 has been read ok
file master_3 was not read
3 
% echo '1
2
3
4
5' | sed -n 'p;n'
1
3
5

Or

% echo '1
2
3
4
5' | awk 'NR%2 == 1'
1
3
5
4

Thanks ... works fine. Thanks for your help