Bash shell 脚本嵌套 while 循环与 IFS

Question

我正在尝试使用 bash shell 脚本解析一组 csv 文件，文件如下所示:

File1: /tmp/test.txt
key1,key1file.txt
key2,key2file.txt
key3,key3file.txt

Files: /tmp/inter/key1file.txt
abc,cdf,123,456

Files: /tmp/inter/key2file.txt
abc,cdf,123,456

Files: /tmp/inter/key3file.txt
abc,cdf,123,456

我尝试使用 2 个 while 循环解析这些文件:

while IFS="," read keycol keyfile
do
    while IFS="," read keyval
     do
     echo "inside inner while loop"
     echo "$keycol|$keyval"
    done < "/tmp/inter/$keyfile"
done < /tmp/test.txt

并期待这段代码输出

key1,abc
key1,cdf
key1,123
key1,456 and so on...

但是，当我运行这段代码时，我没有得到任何输出，这表明第二个循环没有被执行。任何指向正确方向的指示都会有所帮助。谢谢

Answer 1

您在第二个循环中没有按 , 正确拆分。 read 一般按IFS 拆分，给变量赋值，每个变量一个字段，剩下的进入最后提供的变量。但如果您只提供一个变量，所有内容都会存储在那里。

相反，让 read 被 , 拆分成一个数组，然后循环遍历该数组中的值，如下所示:

#!/bin/bash
while IFS="," read keycol keyfile; do
    while IFS="," read -a values; do
        for val in "${values[@]}"; do
            echo "$keycol,$val"
        done
    done < "/tmp/inter/$keyfile"
done < /tmp/test.txt

你会得到:

key1,abc
key1,cdf
key1,123
key1,456
key2,abc
key2,cdf
key2,123
key2,456
key3,abc
key3,cdf
key3,123
key3,456