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→INVESTIGATION 2: ADDITIONAL LOOPING STATEMENTS
# Use the more command to view the text file called '''for-2.bash''' (eg. <span style="color:blue;font-weight:bold;font-family:courier;">more for-2.bash</span>)<br><br>If you are using the nano text editor, refer to notes on text editing in a previous week in the course schedule.<br><br>
# Run your shell script by issuing: <span style="color:blue;font-weight:bold;font-family:courier;">./for-2.bash 10 9 8 7 6 5 4 3 2 1</span><br><br>You should notice the script looped for each argument following the shell script.<br><br>You can also use the for loop with a list using '''command substitution''' - this is an effective technique to loop within a shell script.<br><br>
# First, you need to learn how to use command substitution to store arguments as positional parameters.<br>Issue the following linux command to set positional parameters in your current shell:<br><span style="color:blue;font-weight:bold;font-family:courier;">set apples oranges bananas pears</span><br><br># Issue the following linux command:<br><span style="color:blue;font-weight:bold;font-family:courier;">echo $#</span><br><br>What do you notice?<br><br># Issue the following linux command:<br><span style="color:blue;font-weight:bold;font-family:courier;">echo $*</span><br><br>What do you notice?<br><br>These positional parameters could be used with a for loop. To simplify things, let's create another shell script that uses command substitution and a for loop.<br><br># Use a text editor like vi or nano to create the text file called '''for-2.bash''' (eg. <span style="color:blue;font-weight:bold;font-family:courier;">vi for-3.bash</span>)<br><br>If you are using the nano text editor, refer to notes on text editing in a previous week in the course schedule.<br><br>
# Enter the following lines in your shell script:<br><span style="font-family:courier;">#!/bin/bash<br>clear<br>set 10 9 8 7 6 5 4 3 2 1<br>for x<br>do<br> echo $x<br>done<br>echo "blast-off!"</span><br><br>
# Save your editing session and exit the text editor (eg. with vi: press '''ESC''', then type ''':wx''' followed by '''ENTER''').<br><br>
