Hi Richard, > > > > If you are typing `get_player .* --since 70' into a Linux shell > > I have come across this in relation to bash "The characters *, ? and [ > are called glob characters or wild card characters. If an unquoted > argument contains one or more glob characters, the shell processes the > argument for file name generation. The glob characters are part of > glob patterns which represent file and directory names. These patterns > are similar to regular expressions, but differ in syntax, since they > are intended to match file names and words (not arbitrary strings). > The special constructions that may appear in glob patterns are: ... " > > What that seems to mean is that without quotes around *. a file name > or word can be matched by bash and with quotes an arbitrary string can > be matched as a regex. It is not clear to me why that matters.
The shell is expanding globs before invoking get_iplayer, thus they're not seen by get_iplayer if they match anything. If they don't match anything then they normally remain and are passed to get_iplayer anyway. For the arguments get_iplayer does see, it decides to interpret some of them as regexps. «get_iplayer Railway» has no glob metacharacters to expand so one argument is passed to get_iplayer, it uses it as a regexp, it has no regexp metacharacters so effectively is a substring search of the titles. «get_iplayer R.*way» has a glob metacharacter, the «*», the shell looks at the current directory for entries starting «R.» and ending «way». There are none. The glob remains, unexpanded. get_iplayer has one argument, «R.*way» that it uses as a regexp. There's two regexp metacharacters, «.*», meaning zero or more of any character, used in the search. «get_iplayer R.*way» is run again, and again has a glob, the «*». This time, the current directory has «R.steinway» in it. The argument with the glob is expanded into that and get_iplayer has one argument, «R.steinway», that's used as a regexp. It's unlikely to match any titles, e.g. «Resteinway». To avoid glob expansion, quote the glob metacharacters, «get_iplayer 'R.*way'», and get_iplayer sees the regexp «R.*way». > One thing that does not appear to have happened is infinite recursion, > or even matching of additional programmes. Your unquoted «.*» on Linux would often expand to «. ..», and perhaps more if you've other `dot' files present. These are two regexps interpreted by get_iplayer. It prints titles matching either. Since anything matching the second is also matched by the first, you are seeing any title at least one character long. That's almost like «.*» and «^» except that a zero-length title won't be matched. > As for using a single quote ' as the strongest quote, I suspect the > documentation has used double quotes " for compatibility with Windows. Yes, I expect you're right. Fortunately, I've only had a little exposure to that in the days of DOS. :-) If Windows doesn't treat «^» specially then that could be used instead with no quoting needed. -- Cheers, Ralph. https://plus.google.com/+RalphCorderoy _______________________________________________ get_iplayer mailing list get_iplayer@lists.infradead.org http://lists.infradead.org/mailman/listinfo/get_iplayer
