使用 GNU ed 将字符串替换为文本

发布于 2024-12-13 04:38:11 字数 269 浏览 6 评论 0原文

我想用包含每个可能字符的字符串替换 %foo% （在文件测试中找到）。由于缺少字符限制，以下操作是不可能的（在 BASHv4 中执行）：

echo %foo% > test
replacement="//this//is//a//test"
ed -s test <<< "g/%foo%/s/%foo%/$replacement"

知道如何用每个可能的文本替换 %foo% 吗？

原文

I want to replace %foo% (found in file test) with a string containing every possible character. Because of the missing character limitation, the following is not possible (executed in BASHv4):

echo %foo% > test
replacement="//this//is//a//test"
ed -s test <<< "g/%foo%/s/%foo%/$replacement"

Any idea how to replace %foo% with every possible text?

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仅此而已 2024-12-20 04:38:11

我保证您可以通过在每个前面加上反斜杠来转义斜杠和反斜杠，从而非常接近您的目标。据我所知，这不能在 bash 中一步完成，所以你可以编写一个函数使其可读，或者享受你的倾斜牙签森林之旅：

$ echo %foo% > test
$ replacement="//this//is//a\\\\//test"
$ echo $replacement
//this//is//a\\//test
$ stage1=${replacement//\\/\\\\}
$ echo $stage1
//this//is//a\\\\//test
$ stage2=${stage1//\//\\\/}
$ echo $stage2
\/\/this\/\/is\/\/a\\\\\/\/test
$ ed -s test <<< g/.*foo.*/s/foo/$stage2/p
%//this//is//a\\//test%

换行符仍然是一个问题，但你不想保留无论如何，它们都在 bash 环境变量中，因为那里的空格不是很稳定。

I'll warrant the guess that you will get pretty close to your goal by escaping slashes and backslashes with a prepended backslash each. AFAIK that can't be done in bash in a single step, so you can either write a function to make it readable, or enjoy your trip to the leaning toothpick forest:

$ echo %foo% > test
$ replacement="//this//is//a\\\\//test"
$ echo $replacement
//this//is//a\\//test
$ stage1=${replacement//\\/\\\\}
$ echo $stage1
//this//is//a\\\\//test
$ stage2=${stage1//\//\\\/}
$ echo $stage2
\/\/this\/\/is\/\/a\\\\\/\/test
$ ed -s test <<< g/.*foo.*/s/foo/$stage2/p
%//this//is//a\\//test%

Newlines remain a problem, but then you don't want to keep them in bash environment variables anyway since whitespace isnt' very stable there.

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