如何替换字符串中的字符，但仅当它出现在带分隔符的子字符串中时才如何? [英] How to replace a character in a string but only if it occurs within a delimited substring?

问题描述

我想用一个字符串中的另一个字符替换一个字符，但是仅当该字符出现在该字符串的带分隔符的子字符串中时才可以.例如，对于字符串:

I would like to replace a character with another character in a string but only when the character occurs within a delimited substring of the string. For example, for the string:

b [b] abc [abc] bbb [bbb]

b[b]abc[abc]bbb[bbb]

仅在方括号"[...]"之内，我想将"b"更改为"x".因此，所需的结果是字符串:

I would like to change "b" to "x" but only if it is within square brackets "[...]". Thus, the desired result is the string:

b [x] abc [axc] bbb [xxx]

b[x]abc[axc]bbb[xxx]

我更喜欢sed或bash解决方案，因为它们在我的舒适范围内，但是任何适用于Mac OS X的解决方案都可以.通过搜索，似乎可以使用sed使用负向超前和负向后向实现，但是我不认为这些功能在Mac版本的sed上可用.

My preference would be a sed or bash solution because they are in my comfort zone, but any solution that would work for Mac OS X would be fine. From searching, it seems that this can be accomplished with sed using negative lookahead and negative lookbehind, but I don't believe those features are available on the Mac version of sed.

推荐答案

使用GNU sed:

$ sed -r ':a;s/(\[[^]]*)b/\1x/;ta' <<< "b[b]abc[abc]bbb[bbb]"
b[x]abc[axc]bbb[xxx]

• :a为即将到来的循环添加标签
• s:替代命令
• (\[[^]]*):搜索并捕获[，后跟任何非]字符
• 直到找到b
• 匹配字符串将替换为最初捕获的字符串和x
• ta:如果先前的替换成功，则循环标记为:a(替换任何其他出现的b)
• :a adds a label for upcoming loop
• s : substitute command
• (\[[^]]*) : search and capture a [ followed by any non-] character
• until b is found
• matching string is replaced with initially captured string and a x
• ta : if previous substitution succeed, loops to label :a (replace any other occurrence of b)

对于OS X上的GNU sed:

For GNU sed on OS X :

brew uninstall gnu-sed

更多信息:如何在Mac OS上使用GNU sed X

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