Tenth Line

How would you print just the 10th line of a file?

For example, assume that file.txt has the following content:

Line 1
Line 2
Line 3
Line 4
Line 5
Line 6
Line 7
Line 8
Line 9
Line 10

Your script should output the tenth line, which is:

Line 10

Hint:
1. If the file contains less than 10 lines, what should you output?
2. There's at least three different solutions. Try to explore all possibilities.

解法：

awk '
{
    if(NR==10){
        print $0
    }
}
' < file.txt

过程中忘了重定向文件

awk '
{
   a++;
   if(a == 10){
       print $0;
   }
}
' < file.txt

不使用NR

awk '
{
   a++;
   if(a == 10){
       b = $0;
   }
}
END{
    if(a >= 10){
        print b;
    }
}
' < file.txt