Count number of blank lines in a file

Question

In count (non-blank) lines-of-code in bash they explain how to count the number of non-empty lines.

But is there a way to count the number of blank lines in a file? By

Answer 1

You can also use awk for this:

awk '!NF {sum += 1} END {print sum}' file

From the manual, "The variable NF is set to the total number of fields in the input record". Since the default field separator is the space, any line consisting in either nothing or some spaces will have NF=0.

Then, it is a matter of counting how many times this happens.

Test

$ cat a
aa dd

ffffd


he      llo
$ cat -vet a # -vet to show tabs and spaces
aa dd$
    $
ffffd$
   $
^I$
he^Illo$

Now let's' count the number of blank lines:

$ awk '!NF {s+=1} END {print s}' a
3