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→INVESTIGATION 2: USING VARIABLES IN SHELL SCRIPTS
# Issue the following linux command to run this shell script with the Bourne Shell (i.e. '''sh'''):<br><span style="color:blue;font-weight:bold;font-family:courier;">sh hello</span><br><br>You should see the output of the command that you are located in shows '''sh''' (i.e. the '''Bourne Shell''').<br><br>'''NOTE:''' Due to the fact that shells (and their features) have '''evolved''' over a period of time,<br>an error may occur if you include a ''NEWER'' shell feature (e.g. ''Bash Shell'') in your shell script,<br>but run it in an ''OLDER'' shell (e.g. ''Bourne Shell'').<br><br>You can add a '''special comment''' to the BEGINNING of the FIRST line of your shell script to<br>'''force''' it to run in the shell you want (for example: the Bash shell).<br><br>
# Edit your '''hello''' shell script using a text editor.<br><br>
# Insert the following line at the '''beginning''' of the '''first''' line of your hello file:<br><span style="font-family:courier;">#!/bin/bash</span><br><br>This is referred to as a '''she-bang line'''. It forces the this script to be run in the '''Bash Shell'''.<br>When your Bash Shell script finishes execution, you are returned to your current shell that you are using<br>(which in our case in Matrix, is still the Bash shell).<br><br>
# '''Save''' your editing changes and '''exit''' your text editor.<br><br>
# Issue the following linux command to run this shell script with the Bourne Shell (i.e. '''sh'''):<br><span style="color:blue;font-weight:bold;font-family:courier;">sh hello</span><br><br>You should notice that the shell name is now '''bash''' although you are trying to run it<br>in the ''Bourne Shell'' ('''sh'''). The "she-bang" line ''forces '' a new bash shell to be used to run your shell script.<br><br>
# It is a good idea to rename your shell script to include an '''extension''' to indicate that the file is a Bash Shell script file (referred to as a "''portable Bash shell script''"). <br>Issue the following linux command to rename your shell script file:<br><span style="color:blue;font-weight:bold;font-family:courier;">mv hello hello.bash</span><br><br>
# Run your renamed shell script for confirmation by issuing:<br><span style="color:blue;font-weight:bold;font-family:courier;">./hello.bash</span><br><br>
