sed -e 和 sed -E 的区别 如果讨厌在(前面加\，那么就使用 -E参数吧

官方说明：

  -E, -r, --regexp-extended

                 use extended regular expressions in the script

                 (for portability use POSIX -E).

详细解释

5.2 Basic (BRE) and extended (ERE) regular expression

Basic and extended regular expressions are two variations on the syntax of the specified pattern. Basic Regular Expression (BRE) syntax is the default in sed (and similarly in grep). Use the POSIX-specified -E option (-r, --regexp-extended) to enable Extended Regular Expression (ERE) syntax.

In GNU sed, the only difference between basic and extended regular expressions is in the behavior of a few special characters: ‘?’, ‘+’, parentheses, braces (‘{}’), and ‘|’.

With basic (BRE) syntax, these characters do not have special meaning unless prefixed with a backslash (‘\’); While with extended (ERE) syntax it is reversed: these characters are special unless they are prefixed with backslash (‘\’).

source: https://www.gnu.org/software/sed/manual/sed.html#BRE-vs-ERE

具体实践：

sed -E 's#(http.*github[^/]*/)#https://github.crazypeace.workers.dev/\1#g' 

和

sed -e 's#\(http.*github[^/]*/\)#https://github.crazypeace.workers.dev/\1#g' 

等同.

我个人比较喜欢 -E 的写法，( 不需要用 \ 来转义。