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→INVESTIGATION 1: USING THE SED UTILITY
# Issue the following linux command ('''copy and paste''' to save time):<br><span style="color:blue;font-weight:bold;font-family:courier;">wget <nowiki>https://ict.senecacollege.ca/~murray.saul/uli101/data.txt</nowiki></span><br><br>
# Issue the '''more''' command to quickly view the contents of the '''data.txt''' file.<br>When finished, exit the more command by pressing the letter <span style="color:blue;font-weight:bold;font-family:courier;">q</span><br><br>
# The '''p''' command in sed is used to print or display the contents of a text file.<br>Issue the following linux command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed 'p' data.txt</span><br><br>You should notice that each line appears '''twice'''. The reason why standard output appears twice is that the sed command (without the '''-n option''') displays all lines regardless if they had been specified as a pattern.<br><br>
# Issue the following linux command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed -n 'p' data.txt</span><br><br>What do you notice?<br><br>You can specify an address (line #, line #s or range of line #s) when using the sed utility.<br><br>
# Issue the following linux command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed -n '1 p' data.txt</span><br><br>You should see the first line of the text file displayed.<br><br>
# Issue the following linux command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed -n '2,5 p' data.txt</span><br><br>What do you think is displayed? (in another SSH session, compare with contents in the data.txt text file How do you change command to display lines 2 to confirm).5?<br><br>The '''s''' command is used to substitute patterns (similar to method demonstratedin vi editor).<br><br># Issue the following linux command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed '2,5 s/TUTORIAL/LESSON/g' data.txt</span><br><br>What do you notice? View the original contents of lines 2 to 5 in the '''data.txt''' file in another shell to confirm that the substitution occurred.<br><br>The '''q''' command terminates or '''quits ''' the execution of the sed utility as soon as it read in a particular line or matching pattern.<br><br>
# Issue the following linux command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed '11 q' data.txt</span><br><br>What did you notice?<br><br>You can use regular expressions to select lines that match a pattern. The rules remain the same for using regular expressions as demonstrated in lab8 except the regular expression must be contained within delimiters such as the forward slash "/" when using the sed utility.<br><br>
# Issue the following linux command:<br><span style="color:blue;font-weight:bold;font-family:courier;">sed -n '/^The/ p' data.txt</span><br><br>What do you notice?<br><br>
# Issue the following linux pipeline command:<br><span style="color:blue;font-weight:bold;font-family:courier;">who | sed -n '/^[a-m]/ p' | more</span><br><br>What did you notice?<br><br>
:In the next investigation, you will learn how to manipulate text using the '''awk ''' utility.<br><br>
=INVESTIGATION 2: USING THE AWK UTILITY =
