在awk脚本中使用shell命令，该脚本必须访问awk命令

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Non-awk, inefficient shell tools code:

非awk，低效的shell工具代码：

while read a b c ; do \
    echo -n "$b " ; \
    egrep "^$b " file2 | \
      grep -A 9999999 " $c" | \
      cut -d' ' -f2,3 | \
      sed '1{s/ .*//;t}
           ${s/.* //;t};d' | \
      xargs echo -n  ; \
    echo " $a" ; \
done < file1 | \
  column -t

Output:

输出：

8  4520  7400   5
7  10610 16789  15

The main loop inputs file1 which controls what in file2 needs to be printed. file1 has 3 fields, so read needs 3 variables: $a, $b, and $c. The output uses $b and $a, so those two variables come "for free" -- the first and last lines of the main loop, (both echos), prefix $b and suffix $a to the two numbers in the middle of each line.

主循环输入file1，它控制file2中需要打印的内容。 file1有3个字段，因此read需要3个变量：$ a，$ b和$ c。输出使用$ b和$ a，所以这两个变量“免费” - 主循环的第一行和最后一行（两个回声），前缀$ b和后缀$ a到中间的两个数字每一行。

The egrep prints every line in file2 that begins with $b, but of those lines we only want the one that ends in $c plus the lines after that, which is what grep -A ... prints. Only the middle two columns are needed, so cut prints just those columns. Now we have a two column block of numbers, and we only want the upper left corner, or the lower right corner, which the sed code prints...

egrep打印file2中以$ b开头的每一行，但是在那些行中我们只想要以$ c结尾的行加上之后的行，这就是grep -A ...打印的行。只需要中间两列，因此剪切仅打印那些列。现在我们有一个两列数字块，我们只想要sed代码打印的左上角或右下角...

Any sed code automatically counts lines as it runs. When sed hits the first line, it runs what's in the first set of curly brackets, ('1{<code>}'). If that fails sed checks if it's the last line, ($ means last line), if it is, sed runs what's in the second set of curly brackets, ('${<code>}'). If it's not the first or last line sed deletes it.

任何sed代码在运行时自动计算行数。当sed命中第一行时，它会运行第一组花括号中的内容（'1 {}'）。如果失败则sed检查它是否是最后一行（$表示最后一行），如果是，则sed运行第二组花括号中的内容（'$ {}'）。如果它不是第一行或最后一行，则删除它。

Inside those curly brackets: s/ .*// works just like cut -f 1 would. The closing t means 'GOTO label', but when there's no 'label' sed just starts a new cycle, reading another line -- without t, the code would run the d, and print nothing. With two fields, s/.* // works like cut -f 2, etc.

在那些花括号内：s /。* //就像cut -f 1那样工作。结束t表示'GOTO标签'，但是当没有'标签'时，sed只是开始一个新的循环，读取另一行 - 没有t，代码将运行d，并且什么都不打印。有两个字段，s /.* //就像cut -f 2一样工作，等等。

Each pass of the main while loop sed prints two numbers, but each is on it's own line. Piping that to xargs echo -n puts both numbers on the same line as the $b was printed on.

主while while循环sed的每次传递打印两个数字，但每个都在它自己的行上。管道到xargs echo -n将两个数字放在与打印$ b相同的行上。