![]() The article is written by the author of lzip (which it compares favorably to xz), but does not disclose this. Is my normality detector off today or is this just a wacky thing to want to do?ĥ. By claiming that xz is "telling you what you can't do with your files", it seems that the author considers it perfectly reasonable to append arbitrary data to the end of a file and expect it to continue functioning. The section on trailing data is particularly bizarre. Archives professionals (as in, people who are actually employed by memory institutions) will tell you of many factors (all unmentioned here) that have a bearing on whether a file format (particularly a compressed one) is suitable for use in data preservation.Ĥ. It's not clear what the author means by "long-term archiving". No, it was chosen because of its favorable size/speed tradeoffs.ģ. The article claims xz was chosen by prominent open source projects due to hype. If you want to recover from errors, generate parity files using par2 or zfec.Ģ. If you want to check integrity, use a hashing tool such as sha256sum. Well, xz is for compression, nothing else. The article itself recommends that "a tool is supposed to do one thing and do it well". This article is overblown in its criticisms and has some issues of its own.ġ. A whole subexpression may be enclosed in parentheses to override these precedence rules.OK, I'll bite. Repetition takes precedence over concatenation, which in turn takes precedence over alternation. Two regular expressions may be joined by the infix operator "|" the resulting regular expression matches any string matching either subexpression. Two regular expressions may be concatenated the resulting regular expression matches any string formed by concatenating two substrings that respectively match the concatenated subexpressions. Match the empty string at the end of word. Matches the empty string provided it's not at the edge of a word. Matches the empty string at the edge of a word. Matches the empty string at the end of a line. Matches the empty string at the beginning of a line also represents the characters not in the range of a list. Represents the range if it's not first or last in a list or the ending point of a range in a list. The preceding item is matched at least N times, but not more than M times. ![]() The preceding item is matched N or more times. The preceding item is matched exactly N times. The preceding item will be matched one or more times. The preceding item will be matched zero or more times. The preceding item is optional and will be matched, at most, once. Regular expression metacharacters Ī regular expression may be followed by one of several repetition operators (metacharacters): Any metacharacter with special meaning may be quoted by preceding it with a backslash. Most characters, including all letters and digits, are regular expressions that match themselves. The fundamental building blocks are the regular expressions that match a single character. Regular expressions are constructed analogously to arithmetic expressions by using various operators to combine smaller expressions. Regular expressions What are regular expressions? Ī regular expression is a pattern that describes a set of strings. 1.3 Basic versus extended regular expressions. ![]()
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