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Patterns and string processing in shell scripts

Dec 28, 2008, 20:03 (0 Talkback[s])
(Other stories by Peter Seebach)

"In a pattern, most characters match themselves, and only themselves. The word hello is a perfectly valid pattern; it matches the word hello, and nothing else. A pattern that matches only part of a string is not considered to have matched that string. The word hello does not match the text hello, world. For a pattern to match a string, two things must be true:

"Every character in the pattern must match the string.

"Every character in the string must match the pattern.

"Now, if this were all there were to patterns, a pattern would be another way of describing string comparison, and the rest of this chapter would consist of filler text like "a ... consists of sequences of nonblank characters separated by blanks," or possibly some wonderful cookie recipes. Sadly, this is not so. Instead, there are some characters in a pattern that have special meaning and can match something other than themselves. Characters that have special meaning in a pattern are called wildcards or metacharacters."

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