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
