I wanted to delete all the files from a directory except one. I found my solution here. This solution is using this command:
shopt -s extglobI want to know what this command exactly does, some back end knowledge.
1 Answer
In simple terms, globbing refers to pattern matching. Bash uses simple globbing like, echo l* which expand to list of files in current directory that start with letter l. Of course , as you can guess, it's simple and limited.
Enter extglob. As you can guess, it stands for extended globbing. This option allows for more advanced pattern matching. From man bash:
extglob If set, the extended pattern matching features described above under Pathname Expansion are enabled.And a little before that:
If the extglob shell option is enabled using the shopt builtin, several
extended pattern matching operators are recognized. In the following
description, a pattern-list is a list of one or more patterns separated
by a |. Composite patterns may be formed using one or more of the
following sub-patterns: ?(pattern-list) Matches zero or one occurrence of the given patterns *(pattern-list) Matches zero or more occurrences of the given patterns +(pattern-list) Matches one or more occurrences of the given patterns @(pattern-list) Matches one of the given patterns !(pattern-list) Matches anything except one of the given patternsThere's multitude of ways in which extglob can be used. Quite a few good examples are provided in Linux Journal and Greg's wiki.
