在'for'循环中读取带有空格，带有多个输入文件的制表符的完整行 [英] Reading complete line in 'for' loop with spaces, tabs with multiple input files

问题描述

我看过 'for' 循环的文章.它根据空格(例如空格，制表符或换行符)的出现情况进行拆分.为了解决这个问题，我需要执行以下额外的命令行:

I have seen articles of 'for' loop. It splits on the occurance of whitespace like space, tab, or newline. To get ride of that issue i have following extra line of command:

IFS=$'\n'

但是当我尝试在以下详细信息上解决上述情况时(我有两个文件: 'input1.txt' 和 'input. txt' 放在我当前的目录中):

But when i try to solve the above scenario on following details (i have two files: 'input1.txt' and 'input.txt' on my current directory):

BASH命令:

bash script.sh 'input*'

以下是script.sh中的 'for' 循环块

Below is 'for' loop block in script.sh

for line in $(cat $1)
...
...
done;

执行时出现以下错误:

cat: input1.txt input.txt*: No such file or directory

注意:我要同时 cat 两个文件 input1.txt 和 input .txt

Note: I want to cat both files input1.txt and input.txt

推荐答案

通过重置$IFS，可以禁用分词功能，因为分词功能会导致$1中的模式扩展被视为单独的文件名.这是以 right 方式执行此操作的另一个原因.但是首先，假设您确实要向脚本传递一个模式，而不是仅使用bash script.sh input*使Shell将模式扩展到脚本文件列表.然后你的循环应该像

By resetting $IFS, you disable the word-splitting that would cause the expansion of the pattern in $1 to be treated as separate file names. This is another reason to do this the right way. But first, let's say you really want to pass a pattern to your script, rather than just use bash script.sh input* to have the shell expand the pattern to list of files for your script. Then your loop should be something like

cat $1 | while IFS= read -r line; do
    ...
done

但是，如果任何匹配的文件本身的名称中都有空格，则此方法将无效.使用input a.txt和input b.txt，$1将扩展为 4 个单词input，a.txt，input和b.txt.相反，您应该真正让shell进行扩展，并将每个匹配的文件作为单独的参数传递:

However, this won't work if any of the matching files themselves have whitespace in their names; with input a.txt and input b.txt, $1 will expand to 4 words input, a.txt, input, and b.txt. Instead, you should really let the shell do the expansion and pass each matching file as a separate argument:

bash script.sh input*

并在您的脚本中:

for f in "$@"; do
    while IFS= read -r line; do
        ...
    done < "$f"
done

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