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→INVESTIGATION 1: SIMPLE & COMPLEX REGULAR EXPRESSIONS
# Issue the following Linux pipeline command:<br><span style="color:blue;font-weight:bold;font-family:courier;">grep -w -i "^the" textfile1.txt</span><br><br>The '''^''' symbol is referred to as an '''anchor'''. In this case, it only matches<br>the word "'''the'''" (both upper or lowercase) at the <u>beginning</u> of the string.<br>The '''$''' symbol is used to anchor patterns at the end of strings.<br><br>
# Issue the following Linux pipeline command:<br><span style="color:blue;font-weight:bold;font-family:courier;">grep -w -i "the$" textfile1.txt</span><br><br>What do you notice?<br><br>
# Issue the following Linux pipeline command to anchor the work "the" simultaneously at the <u>beginning </u> and the <u>end </u> of the string:<br><span style="color:blue;font-weight:bold;font-family:courier;">grep -w -i "^the$" textfile1.txt </span><br><br>What do you notice?<br><br>Anchoring patterns at both the <u>beginning</u> and <u>ending</u> of strings can greatly assist for more robust search patterns.<br><br>We will now be demonstrating the usefulness of '''simultaneous anchoring''' with other complex regular expressions symbols.<br><br>
# Issue the following command to match strings that begin with 3 characters:<br><span style="color:blue;font-weight:bold;font-family:courier;">grep "^..." textfile1.txt</span><br><br>What do you notice? Can lines that contain '''less than 3 characters''' be displayed?<br><br>
# Issue the following command to match strings that begin and end with 3 characters:<br><span style="color:blue;font-weight:bold;font-family:courier;">grep "^...$" textfile1.txt</span><br><br>What do you notice compared to the previous command?<br><br>
