Đang chuẩn bị liên kết để tải về tài liệu:
Classic Shell Scripting phần 2

Được gọi là một biểu hiện khoảng thời gian này phù hợp một loạt các lần xuất hiện của nhân vật duy nhất ngay lập tức đứng trước. \ {n \} phù hợp chính xác xuất hiện n \ {n \} phù hợp với ít nhất là n lần xuất hiện, và \ {n, m \} phù hợp bất kỳ số lượng xuất hiện giữa n và m. n và m phải được giữa 0 và RE_DUP_MAX (giá trị tối thiểu: 255), | Simpo PDF Merge and Split UnregisterecXVersiond- ihttp www.simpopdf.com Character BRE ERE Meaning in a pattern n m BRE Termed an interval expression this matches a range of occurrences of the single character that immediately precedes it. n matches exactly n occurrences n matches at least n occurrences and n m matches any number of occurrences between n and m. n and m must be between 0 and RE_DUP_MAX minimum value 255 inclusive. BRE Save the pattern enclosed between and in a special holding space. Up to nine subpatterns can be saved on a single pattern. The text matched by the subpatterns can be reused later in the same pattern by the escape sequences 1 to 9. For example ab . 1 matches two occurrences of ab with any number of characters in between. n BRE Replay the nth subpattern enclosed in and into the pattern at this point. n is a number from 1 to 9 with 1 starting on the left. n m ERE Just like the BRE n m earlier but without the backslashes in front of the braces. ERE Match one or more instances of the preceding regular expression. ERE Match zero or one instances of the preceding regular expression. I ERE Match the regular expression specified before or after. ERE Apply a match to the enclosed group of regular expressions. Table 3-2 presents some simple examples. Table 3-2. Simple regular expression matching examples Expression Matches tolstoy The seven letters tolstoy anywhere on a line Atolstoy The seven letters tolstoy at the beginning of a line tolstoy The seven letters tolstoy at the end of a line Atolstoy A line containing exactly the seven letters tolstoy and nothing else Tt olstoy Either the seven letters Tolstoy or the seven letters tolstoy anywhere on a line tol.toy The three letters tol any character and the three letters toy anywhere on a line tol. toy The three letters tol any sequence of zero or more characters and the three letters toy anywhere on a line e.g. toltoy tolstoy tolWHOtoy and so on 3.2.1.1. POSIX bracket expressions In order to .