UNIX for Dummies Questions & Answers

Hello,

I have a file with over 48000 lines and I need to select certain parts of the file. I know which awk commands work for what I need, I just need some help putting together a loop that will repeat the command. These are the commands that work:

awk 'NR < 6' plot.out > plot.test (I get the first 5 lines of plot.out)

awk 'NR==15,NR==17' plot.out >> plot.test (now I need these lines)
awk 'NR==30,NR==32' plot.out >> plot.test (etc.)
awk 'NR==45,NR==47' plot.out >> plot.test
awk 'NR==60,NR==62' plot.out >> plot.test
awk 'NR==75,NR==77' plot.out >> plot.test
awk 'NR==90,NR==92' plot.out >> plot.test
awk 'NR==105,NR==107' plot.out >> plot.test
awk 'NR==120,NR==122' plot.out >> plot.test
awk 'NR==135,NR==137' plot.out >> plot.test


Please help. All the loops I make don't work I know this is simple for somebody out there.....

I see that NR is incremented by 15

cat plot.out|awk -v x=15 'NR==x,NR==x+2 {x=x+15};END{print $0}'