如何在bash中打印文件末尾的第n行？

Question

Is there a way to print the nth line of a file, counting from the back of the file?

I know how to do it from the front of the file, but doing it from the back of the file seems to be more tricky.

Answer 1

The quick and easy way is tail -n $n file | head -n 1 tail -n $n file | head -n 1 .

A more fun way with awk is:

awk -v n=$n '{x[NR%n]=$0}END{print x[(NR+1)%n]}' file

If you have fewer than n lines, the tail | head tail | head method will print the first line of the file, the awk way will print a blank line.

Answer 2

Quick and dirty, 100th line from the end:

tail -n 100 yourfile | head -n 1

You'll get the first line of the file if it has less than 100 lines.