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I've got an input file like this:

line 1 line 2 line 3 line 4 line 5 line 6

I'd like to use awk to insert a blank line every few lines; for example, every two:

line 1 line 2 line 3 line 4 line 5 line 6

How can I get awk to put a blank line into my file every n lines?

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5 Answers 5

Reset to default
30

A more "awk-ish" way to write smcameron's answer:

awk -v n=5 '1; NR % n == 0 {print ""}'

The "1;" is a condition that is always true, and will trigger the default action which is to print the current line.

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2 Comments

Same here, no? print line and print newline would need to be reversed, otherwise the newline is print before every 5th line instead of after it.
I would probably write that as '{print} NR % n == 0 { print "" }, but that is purely a style issue.
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awk '{ if ((NR % 5) == 0) printf("\n"); print; }'

for n == 5, of course. Substitute whatever your idea of n is.

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2 Comments

If n=1, the following seem to work: awk '{print; printf("\n");}' or simply awk '{print; print "";}'
This will put the first new line before the 5th line instead of after is. print and the printf need to be reversed..
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More awkishness:

awk 'ORS=NR%5?RS:RS RS'

For example:

$ printf "%s\n" {1..12} | awk 'ORS=NR%5?RS:RS RS' 1 2 3 4 5 6 7 8 9 10 11 12
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6 
awk '{print; if (FNR % 5 == 0 ) printf "\n";}' your_file

I guess 'print' should be before 'printf', and FNR is more accurate for your task.

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2 
$ awk -v n=5 '$0=(!(NR%n))?"\n"$0:$0'

If you want to change 'n', please set the parameter 'n' by awk's -v option.

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1 Comment

That will be problematic when a line is blank or consists of a zero.