Whitespace in the regular expression that isn't inside a character class is ignored. 在正則表達式中不在字元類中的空白符被忽略。
A word is defined as a sequence of alphanumeric characters, so the end of a word is indicated by whitespace or a non-alphanumeric character. 單詞被定義為一個字母數字序列，因此詞尾就是用空白符或非字母數字元來標示的。
Any whitespace character that is not a line separator. 非行分隔符的任意空白字元。
Separate multiple switches and multiple arguments with one space character. 用一個空白字元分隔多個開關和多個參數。
