Using variables in printf format

Question

Suppose I have a file like this:

$ cat a
hello this is a sentence
and this is another one

And I want to print the first two columns with so

Answer 1

Using simple string concatenation.

Here "%", n and "-s%s\n" concatenates as a single string for the format. Based on the example below, the format string produced is %7-s%s\n.

awk -v n=7 '{ printf "%" n "-s%s\n", $1, $2}' file
awk '{ n = 7; printf "%" n "-s%s\n", $1, $2}' file

Output:

hello  this
and    this