为 sed 替换模式转义字符串 [英] Escape a string for a sed replace pattern

问题描述

在我的 bash 脚本中，我有一个外部(从用户接收)字符串，我应该在 sed 模式中使用它.

In my bash script I have an external (received from user) string, which I should use in sed pattern.

REPLACE="<funny characters here>"
sed "s/KEYWORD/$REPLACE/g"

如何转义 $REPLACE 字符串，以便 sed 安全地接受它作为字面替换?

How can I escape the $REPLACE string so it would be safely accepted by sed as a literal replacement?

注意: KEYWORD 是一个没有匹配等的哑子字符串.它不是由用户提供的.

NOTE: The KEYWORD is a dumb substring with no matches etc. It is not supplied by user.

推荐答案

警告:这不考虑换行符.有关更深入的答案，请参阅 this SO-question 来可靠地转义正则表达式元字符.(谢谢，Ed Morton 和 Niklas Peter)

Warning: This does not consider newlines. For a more in-depth answer, see this SO-question instead. (Thanks, Ed Morton & Niklas Peter)

请注意，逃避一切是一个坏主意.Sed 需要对许多字符进行转义以获得它们的特殊含义.例如，如果您对替换字符串中的数字进行转义，它将变成反向引用.

Note that escaping everything is a bad idea. Sed needs many characters to be escaped to get their special meaning. For example, if you escape a digit in the replacement string, it will turn in to a backreference.

正如 Ben Blank 所说，替换字符串中只有三个字符需要转义(转义自己，正斜杠代表语句结束，& 代表全部替换):

As Ben Blank said, there are only three characters that need to be escaped in the replacement string (escapes themselves, forward slash for end of statement and & for replace all):

ESCAPED_REPLACE=$(printf '%s
' "$REPLACE" | sed -e 's/[/&]/\&/g')
# Now you can use ESCAPED_REPLACE in the original sed statement
sed "s/KEYWORD/$ESCAPED_REPLACE/g"

如果您需要对 KEYWORD 字符串进行转义，以下是您需要的:

If you ever need to escape the KEYWORD string, the following is the one you need:

sed -e 's/[]/$*.^[]/\&/g'

并且可以用于:

KEYWORD="The Keyword You Need";
ESCAPED_KEYWORD=$(printf '%s
' "$KEYWORD" | sed -e 's/[]/$*.^[]/\&/g');

# Now you can use it inside the original sed statement to replace text
sed "s/$ESCAPED_KEYWORD/$ESCAPED_REPLACE/g"

请记住，如果您使用 / 以外的字符作为分隔符，则需要将上述表达式中的斜线替换为您正在使用的字符.有关解释，请参阅 PeterJCLaw 的评论.

Remember, if you use a character other than / as delimiter, you need replace the slash in the expressions above wih the character you are using. See PeterJCLaw's comment for explanation.

已由于之前未考虑到的某些极端情况，上述命令已更改数次.查看编辑历史以了解详细信息.

Edited: Due to some corner cases previously not accounted for, the commands above have changed several times. Check the edit history for details.

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