击：简单的方法来传递一个＆QUOT; RAW＆QUOT;字符串用grep？ [英] Bash: easy way to pass a "raw" string to grep?

问题描述

的grep 不能在命令行中使用时，美联储原始字符串，因为一些字符需要转义不被作为文字处理。例如：

grep can't be fed "raw" strings when used from the command-line, since some characters need to be escaped to not be treated as literals. For example:

$ grep '(hello|bye)' # WON'T MATCH 'hello'
$ grep '\(hello\|bye\)' # GOOD, BUT QUICKLY BECOMES UNREADABLE

我用的printf 来自动转义字符串：

$ printf '%q' '(some|group)\n'
\(some\|group\)\\n

这产生字符串的一个bash转义版本，并使用反引号，这可以很容易地传递给grep的呼叫：

This produces a bash-escaped version of the string, and using backticks, this can easily be passed to a grep call:

$ grep `printf '%q' '(a|b|c)'`

然而，这显然不是意味着这样的：在输出一些字符都没有逃过，有些是不必要如此。例如：

However, it's clearly not meant for this: some characters in the output are not escaped, and some are unnecessarily so. For example:

$ printf '%q' '(^#)'
\(\^#\)

的 ^ 传递给的grep 字符时，不应该逃脱。

The ^ character should not be escaped when passed to grep.

是否有一个命令行工具，它原始字符串并返回，可以直接作为使用grep模式字符串的一个bash转义版本？我怎么能在纯bash中实现这一点，如果不是？

Is there a cli tool that takes a raw string and returns a bash-escaped version of the string that can be directly used as pattern with grep? How can I achieve this in pure bash, if not?

推荐答案

如果您正在试图将的grep 使用扩展的正前pression语法的方式要做到这一点是使用的grep -E （又名 egrep的）。你也应该知道的grep -F （又名 fgrep一样），并在GNU Coreutils的更新版本，的grep -P 。

If you are attempting to get grep to use Extended Regular Expression syntax, the way to do that is to use grep -E (aka egrep). You should also know about grep -F (aka fgrep) and, in newer versions of GNU Coreutils, grep -P.

背景：原的grep 有一个相当小套regex操作符的;这是肯·汤普逊原有的常规前pression实施。新版本具有扩展的剧目后来发展，以及兼容性的原因，有一个不同的名称。随着GNU 的grep ，只存在一个二进制文件，它明白如果援引为的grep 传统的，基本RE语法和如果调用ERE为 egrep的。从 egrep的在的grep 可通过使用反斜线引入特殊的意义。

Background: The original grep had a fairly small set of regex operators; it was Ken Thompson's original regular expression implementation. A new version with an extended repertoire was developed later, and for compatibility reasons, got a different name. With GNU grep, there is only one binary, which understands the traditional, basic RE syntax if invoked as grep, and ERE if invoked as egrep. Some constructs from egrep are available in grep by using a backslash escape to introduce special meaning.

随后，Perl编程语言，甚至进一步扩展形式主义;此正则表达式方言似乎是大多数新人错误地期待的grep ，也支持。随着的grep -P ，它;但这还没有被广泛支持的所有平台。

Subsequently, the Perl programming language has extended the formalism even further; this regex dialect seems to be what most newcomers erroneously expect grep, too, to support. With grep -P, it does; but this is not yet widely supported on all platforms.

所以，在的grep ，以下字符有特殊含义： ^ $ [] * \\

So, in grep, the following characters have a special meaning: ^$[]*.\

在 egrep的，以下字符也有特殊的意义：（）| + {} ？。 （对于重复的括号是不是在原来的 egrep的）的分组圆括号还能够与反向引用\\ 1 ， \\ 2 等

In egrep, the following characters also have a special meaning: ()|+?{}. (The braces for repetition were not in the original egrep.) The grouping parentheses also enable backreferences with \1, \2, etc.

在的grep 的很多版本，你可以放一个反斜杠<$ C之前获得 egrep的行为$ C> egrep的特价商品。也有类似的特殊序列 \\＆LT; \\方式＆gt;

In many versions of grep, you can get the egrep behavior by putting a backslash before the egrep specials. There are also special sequences like \<\>.

在Perl中，一个巨大的像 \\额外的转义数w \\ S \\ ð进行了介绍。在Perl 5，正则表达式设施被大大延长，与非贪婪匹配 *？ + 等，非分组括号（？：...），向前看符号，lookbehinds等

In Perl, a huge number of additional escapes like \w \s \d were introduced. In Perl 5, the regex facility was substantially extended, with non-greedy matching *? +? etc, non-grouping parentheses (?:...), lookaheads, lookbehinds, etc.

...说了这么多，如果你真的想 egrep的常规EX pressions转换为的grep 常规EX pressions的而不调用任何外部进程的尝试 $ {正则表达式/模式/替换} 为每个 egrep的特殊字符;但认识到，这不处理字符类，否定字符类或反斜线正确逃逸。

... Having said that, if you really do want to convert egrep regular expressions to grep regular expressions without invoking any external process, try ${regex/pattern/substitution} for each of the egrep special characters; but recognize that this does not handle character classes, negated character classes, or backslash escapes correctly.

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