通过在bash文件行循环，不使用标准输入 [英] Looping through lines in a file in bash, without using stdin

问题描述

我对下面的情况大感迷惑。

I am foxed by the following situation.

我有，我想通过线线运行，在一个循环，在bash文件LIST.TXT。在LIST.TXT一个典型的行有空间，但问题是该循环包含一个读命令。我想写这个循环在bash，而不是像perl的。我不能做到这一点： - （

I have a file list.txt that I want to run through line by line, in a loop, in bash. A typical line in list.txt has spaces in. The problem is that the loop contains a "read" command. I want to write this loop in bash rather than something like perl. I can't do it :-(

下面就是我通常会写一个循环从文件里逐行读取：

Here's how I would usually write a loop to read from a file line by line:

while read p; do
  echo $p
  echo "Hit enter for the next one."
  read x
done < list.txt

这不工作，虽然自然是因为读X将从LIST.TXT阅读，而不是键盘。

This doesn't work though, because of course "read x" will be reading from list.txt rather than the keyboard.

和这不工作之一：

for i in `cat list.txt`; do
    echo $i
    echo "Hit enter for the next one."
  read x
done

由于LIST.TXT线路有空格

because the lines in list.txt have spaces in.

我有两个提出的解决方案，这两个臭：

I have two proposed solutions, both of which stink:

1），我可以LIST.TXT编辑，并在全球以THERE_SHOULD_BE_A_SPACE_HERE全部替换空间。然后我可以使用类似中美战略经济对话，我的循环中，用空格来代替THERE_SHOULD_BE_A_SPACE_HERE，我会准备就绪。如果任何LIST.TXT的线路包含短语THERE_SHOULD_BE_A_SPACE_HERE（这样可以恶意用户乱了我），我不喜欢这样的愚蠢的原因，它会失败。

1) I could edit list.txt, and globally replace all spaces with "THERE_SHOULD_BE_A_SPACE_HERE" . I could then use something like sed, within my loop, to replace THERE_SHOULD_BE_A_SPACE_HERE with a space and I'd be all set. I don't like this for the stupid reason that it will fail if any of the lines in list.txt contain the phrase THERE_SHOULD_BE_A_SPACE_HERE (so malicious users can mess me up).

2）我可以使用whil​​e循环：标准输入，然后在每个循环我其实例如推出新的终端，这将是不受影响的事情上，在原来的壳，涉及标准输入。我想这和我没有得到它的工作，但它是丑：我想换这一切了一个shell脚本，我不希望这样的shell脚本是随机打开新窗口。什么是好的，什么，都可能是这个问题的答案，将是如果我能想出​​如何以某种方式在调用命令和饲料的命令给它一个新的外壳，而不饲养标准输入到它，但我不能让它的工作。例如，这不工作，我真的不知道为什么：

2) I could use the while loop with stdin and then in each loop I could actually launch e.g. a new terminal, which would be unaffected by the goings-on involving stdin in the original shell. I tried this and I did get it to work, but it was ugly: I want to wrap all this up in a shell script and I don't want that shell script to be randomly opening new windows. What would be nice, and what might somehow be the answer to this question, would be if I could figure out how to somehow invoke a new shell in the command and feed commands to it without feeding stdin to it, but I can't get it to work. For example this doesn't work and I don't really know why:

while read p; do 
  bash -c "echo $p; echo ""Press enter for the next one.""; read x;"; 
done < list.txt

这似乎尝试，失败，因为读X，尽管在不同的外壳是弄好了，还是看似从LIST.TXT阅读。但我觉得我可能会关闭这一个 - 谁知道

This attempt seems to fail because "read x", despite being in a different shell somehow, is still seemingly reading from list.txt. But I feel like I might be close with this one -- who knows.

帮助！

推荐答案

您必须为不同的文件描述符打开

You must open as a different file descriptor

while read p <&3; do
    echo "$p"
    echo 'Hit enter for the next one'
    read x
done 3< list.txt

更新：只要忽略下面的评论中长时间的讨论。它无关的问题或这个答案。

Update: Just ignore the lengthy discussion in the comments below. It has nothing to do with the question or this answer.

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