不转义的代码(不匹配任何数字):
代码: 全选
$ cat |sed -n '/^[0-9]+$/p'
1
12
123
^C
$
代码: 全选
$ cat |sed -n '/^[0-9]\+$/p'
1
1
12
12
123
123
^C
$
貌似是Basic Regular Experssions 和 Extended Regular Expression 的区别.
然后那个特殊的转义貌似是特殊实现的关系.
https://www.google.com/search?newwindow ... WB_VuQpkYQ
https://stackoverflow.com/questions/220 ... oesnt-work
https://www.google.com/search?newwindow ... igyVddbUvQ
https://www.regular-expressions.info/posix.html