在使用grep的的星座 [英] Using the star sign in grep

问题描述

我试图在Linux / bash的

I am trying to search for the substring "abc" in a specific file in linux/bash

所以，我做的：

grep '*abc*' myFile

它返回什么。

但是，如果我做的：

grep 'abc' myFile

它正确返​​回匹配。

It returns matches correctly.

现在，这是不是我的问题。但是，如果我想对grep更复杂的字符串，比如

Now, this is not a problem for me. But what if I want to grep for a more complex string, say

*abc * def *

我

将如何完成它使用grep？

How would I accomplish it using grep?

推荐答案

星号只是一个重复操作符，但你需要告诉它你重复一下。 / * ABC * / 匹配包含AB和零个或多个C的一个字符串（因为第二个*是放在c;第一个是没有意义的，因为没有什么让它重复） 。如果你想匹配任何东西，你需要说 * - 点指任何字符（的中的某些准则）。如果你想只匹配ABC，你可能只是说的grep'ABC'MYFILE 。为了让您更复杂的比赛，你需要使用 * - 的grep'ABC *高清'MYFILE 将匹配其次，它包含ABC字符串通过DEF与可选的东西之间​​。

The asterisk is just a repetition operator, but you need to tell it what you repeat. /*abc*/ matches a string containing ab and zero or more c's (because the second * is on the c; the first is meaningless because there's nothing for it to repeat). If you want to match anything, you need to say .* -- the dot means any character (within certain guidelines). If you want to just match abc, you could just say grep 'abc' myFile. For your more complex match, you need to use .* -- grep 'abc.*def' myFile will match a string that contains abc followed by def with something optionally in between.

基于评论更新：

* 在常规的前pression是不完全在控制台一样*。在控制台中，*是一个水珠的一部分构建，只是充当一个通配符（比如 LS * .LOG 将列出在.LOG结尾）的所有文件。然而，在常规的前pressions，*是修饰的，这意味着它仅适用于字符或组preceding它。如果你想在*定期EX pressions作为通配符，你需要使用 * 为previously提到的 - 点是通配符和明星，修改点时，意味着找到一个或多个点; IE浏览器。找到一个或多个任意字符。

* in a regular expression is not exactly the same as * in the console. In the console, * is part of a glob construct, and just acts as a wildcard (for instance ls *.log will list all files that end in .log). However, in regular expressions, * is a modifier, meaning that it only applies to the character or group preceding it. If you want * in regular expressions to act as a wildcard, you need to use .* as previously mentioned -- the dot is a wildcard character, and the star, when modifying the dot, means find one or more dot; ie. find one or more of any character.

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