Linux Shell Scripting Cookbook - Third Edition

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Let's see a few examples of regular expressions:

This regular expression would match any single word:

( +[a-zA-Z]+ +) 

The initial + characters say we need 1 or more spaces.

The [a-zA-Z] set is all upper– and lower–case letters. The following plus sign says we need at least one letter and can have more.

The final + characters say we need to terminate the word with one or more spaces.

This would not match the last word in a sentence. To match the last word in a sentence or the word before a comma, we write the expression like this:

( +[a-zA-Z]+[?,\.]? +) 

The [?,\.]? phrase means we might have a question mark, comma, or a period, but at most one. The period is escaped with a backslash because a bare period is a wildcard that ...