The problem is here: https://leetcode.com/problems/tenth-line/. It's a bash programming, reading the 10th line of a file and output in stdout. I think there are lots of methods to do this, here I write some.

If the file has more than 10 lines, I can output like this:

$ head -n 10 file.txt | tail -n 1

BUT, reality is not, above command failed. Then I have the following:

i=0
while read line
do
    i=$(($i+1))
    if [ $i -eq 10 ]; then
        echo $line
        break
    fi
done < file.txt

This time works.