有没有一种简单的方法来传递“原始"消息?字符串到grep? [英] Is there an easy way to pass a "raw" string to grep?

问题描述

grep时，不能将它们输入原始"字符串，因为某些字符需要转义以免被视为文字.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

我正在使用printf自动转义字符串:

I was using printf to auto-escape strings:

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

这将生成字符串的以bash格式转义的版本，并使用反引号将其轻松传递给grep调用:

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)'`

但是，这显然不是要这样做的:输出中的某些字符未转义，而某些字符不必要地转义.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' '(^#)'
\(\^#\)

^字符在传递给grep时不应转义.

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

是否存在一个cli工具，该工具可以接收原始字符串并返回可以以grep形式直接用作模式的字符串的bash转义版本?如果不是，我怎么能用纯bash做到这一点?

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

如果您试图让grep使用扩展正则表达式语法，则该方法是使用grep -E(又名egrep) .您还应该了解grep -F(又名fgrep)，以及在较新版本的GNU Coreutils中的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:原始的grep具有相当少的一组正则表达式运算符.这是肯·汤普森(Ken Thompson)最初的正则表达式实现.后来开发了具有扩展曲目的新版本，并且出于兼容性原因，使用了不同的名称.对于GNU grep，只有一个二进制文件，如果以grep调用，则可以理解传统的基本RE语法，而如果以egrep调用，则可以理解为ERE.通过使用反斜杠转义符引入特殊含义，可以在grep中使用egrep中的某些构造.

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编程语言进一步扩展了形式主义.这个正则表达式方言似乎也是大多数新手错误地期望grep支持的语言.使用grep -P可以；但这尚未在所有平台上得到广泛支持.

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.

因此，在grep中，以下字符具有特殊含义:^$[]*.\

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

在egrep中，以下字符也具有特殊含义:()|+?{}. (重复括号不在原始的egrep中.)分组括号还启用了\1，\2等的反向引用.

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grep的许多版本中，可以通过在egrep特殊字符前加反斜杠来获得egrep行为.还有一些特殊的序列，例如\<\>.

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，引入了许多其他的转义字符，例如\w \s \d.在Perl 5中，正则表达式功能得到了实质性的扩展，具有非贪婪匹配*? +?等，非分组括号(?:...)，超前，超前等等.

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.

...话虽如此，如果您确实希望在不调用任何外部进程的情况下将egrep正则表达式转换为grep正则表达式 ，请为每个egrep特殊字符；但是请注意，这不能正确处理字符类，否定字符类或反斜杠转义符.

... 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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