awk 打印没有文件

Question

如何在没有文件的情况下使用 awk 进行打印。

script.sh
#!/bin/sh
for i in {2..10};do
awk '{printf("%.2f %.2f\n", '$i', '$i'*(log('$i'/('$i'-1))))}'
done

sh 脚本.sh

Desired output
2   value
3   value
4   value
and so on

value表示计算后的数量

Answer 1

如果您没有通过文件或标准输入向 awk 提供任何输入，则需要 BEGIN 块。即使在打开第一个文件之前，这个块也会在 awk 执行的最开始执行。
awk 'BEGIN{printf.....
所以它就像:

从手册页:

Gawk executes AWK programs in the following order. First, all variable assignments specified via the -v option are performed. Next, gawk compiles the program into an internal form. Then, gawk executes the code in the BEGIN block(s) (if any), and then proceeds to read each file named in the ARGV array. If there are no files named on the command line, gawk reads the standard input.

awk结构体:

 awk 'BEGIN{get initialization data from this block}{execute the logic}' optional_input_file