How To Count the Number of Non-Empty Output Lines in Linux

We primarily use the wc (word count) command to count lines, words, bytes, and characters.

wc [flags] file.txt

wc -l : number of lines
wc -w : number of words
wc -c : number of bytes
wc -m : number of characters
wc -L : length of the longest line

Count Number of Output Lines from Another Command#

Suppose we want to run main.py.

python main.py

We can count the number of lines of output by redirecting the output (|) to wc.

Note that wc -l counts empty lines.

python main.py | wc -l

In order to count only non-empty lines, we can pipe together a series of commands.

python main.py | sed '/^$/d'| awk '{print NR}' | sort -nr | sed -n '1p'

You can replace python main.py with any command that outputs to terminal.

Suppose we wanted to count the total number of lines in file.txt.

This still includes empty lines.

wc -l file.txt

Let’s count just the non-empty lines.

sed '/^$/d' file.txt | awk '{print NR}' | sort -nr | sed -n '1p'