Question

Is it possible to retrieve data from lines number 1, 11, 21 ,31 from a text file using Linux commands?

I need to do the same for 2, 12, 22, 32 and so on.

Answer 1

You can use awk for this:

awk '(NR % 10 == 1){ print }' your_input_file

For example:

 $ seq 1 100|awk '(NR%10 == 2){print}'
2
12
22
32
42
52
62
72
82
92

As glenn jackman points out, you can parametrize the awk script to make it more easy to use. And given that print is the default action, you can simply write:

 $ seq 1 20|awk -v step=10 -v idx=3 'NR%step==idx'
3
13