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→INVESTIGATION 2: ADDITIONAL LOOPING STATEMENTS
# 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-3.bash''' (eg. <span style="color:blue;font-weight:bold;font-family:courier;">vi for-3.bash</span>)<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="color:blue;font-family:courier;font-weight:bold;">#!/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>
# Add execute permissions for the owner of this script and run this script.<br>What do you notice? How does the result differ from the shell script called for-2.bash. Why?<br><br>Let's create another shell script to '''run a loop for each file''' that is contained in your current directory using '''command substitution'''.<br><br>
# Use a text editor like vi or nano to create the text file called '''for-4.bash''' (eg. <span style="color:blue;font-weight:bold;font-family:courier;">vi for-4.bash</span>)<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="color:blue;font-family:courier;font-weight:bold;">#!/bin/bash<br>clear<br>set $(ls)<br>echo Here are files in my current directory:"<br>echo<br>for x<br>do<br> echo " $x"<br>done</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>
# Add execute permissions and run this shell script<br>What do you notice?<br><br>We can reduce a line in our shell script by using '''command substitution''' in the for loop instead of using the '''set''' command.<br>Let's demonstrate this in another shell script.<br><br>
