You can issue the grep command with the -w option to only match the pattern as a word. You will notice that the pattern " the" is matched including larger words like " them" and " their". What do you notice is different when issuing this command? Issue the grep Linux command with the -i option to ignore case sensitively:.Take a few moments to view the output and observe the matched patterns. Issue the following Linux command to match the pattern the within textfile1.txt:.Notice the pattern matches larger words like " their" or " them". Output of grep command matching simple regular expression " the" (only lowercase). Zero or more occurrences of previous character.Įxamples of complex regular expressions are displayed below: Represents a single character but with restrictions. Represents a single character that can be any type of character. Match lines the begin (^) or end ($) with a pattern. The most common complex regular expression symbols are displayed below: The problem with just using simple ( literal) regular expressions is that only simple or general patterns are matched.Ĭomplex Regular Expressions use symbols to help match text for more precise (complex) patterns. The simplest regular expression is a series of letters and numbers, (tabs or spaces).Ī simple ( literal) regular expression consists of normal characters, which used to match patterns.Īlthough there are many Linux commands that use regular expressions, the grep command is a useful command to learn how to display matches of patterns of strings within text files. Of issuing Linux commands using a Linux pipeline command.Ī simple ( literal) regular expression is a series of letters and numbers (tabs or spaces). This usually refers to text that is contained inside a file or text as a result Strings of text can be compared to this pattern to see if there is a match. Using grep Command with Regular ExpressionsĪ regular expression is a combination of two types of characters: literals and special characters.List several Linux commands that can use regular expressions.Understand and use command symbols for Extended Regular Expressions and their purpose.Understand and use common symbols for Complex Regular Expressions and their purpose.Explain the purpose of Literal (Simple) Regular Expressions.Explain the difference between Regular Expressions and Filename Expansion.Main Objectives of this Practice Tutorial 6.2 REVIEW QUESTIONS: REGULAR EXPRESSIONS (INCLUDING EXTENDED REGULAR EXPRESSIONS). 6.1 REVIEW QUESTIONS: SIMPLE & COMPLEX REGULAR EXPRESSIONS.5 INVESTIGATION 3: OTHER COMMANDS USING REGULAR EXPRESSIONS.4 INVESTIGATION 2: EXTENDED REGULAR EXPRESSIONS.3 INVESTIGATION 1: SIMPLE & COMPLEX REGULAR EXPRESSIONS.2.3 Complex / Extended Regular Expressions.2.2 Literal (Simple) Regular Expressions.1.1 Main Objectives of this Practice Tutorial.
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