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→INVESTIGATION 1: CREATING A SHELL SCRIPT
# Issue a command to '''confirm''' you are located in your home directory.<br><br>We want to create a Bash Shell script to welcome the user by their username. Let's first provide some useful tips in terms<br>of selecting an appropriate name for the shell script.<br><br>
# Issue the following linux command to check if your intended shell script name<br>is already exists to be run automatically from the Bash shell:<br><span style="color:blue;font-weight:bold;font-family:courier;">which hello</span><br><br>You should notice that there is no output and therefore, this shell script name can be used.<br>On the other hand, if you wanted to create a file called sed, then the '''which sed''' command<br>would indicate it is already being used by the shell and that '''sed''' wouldn't be an appropriate shell script name to use.<br><br>
# Use a '''text editor ''' like vi or nano to create the text file called hello (eg. <span style="color:blue;font-weight:bold;font-family:courier;">vi hello</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 two lines in your shell script, replacing "your-username" with your actual name:<br><span style="font-family:courier;">clear<br>echo "Hello your-username"</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># Issue the following linux command to run your shell script in your current directory:<br><span style="color:blue;font-weight:bold;font-family:courier;">./hello</span><br><br>You should notice an error indicating you don't have permissions to run the file.<br>You need to first esirst add execute permissions prior to running the shell script.<br><br>
# Issue the following linux command to add execute permissions for your shell script:<br><span style="color:blue;font-weight:bold;font-family:courier;">chmod u+x hello</span><br><br>
# Re-run your shell script: <span style="color:blue;font-weight:bold;font-family:courier;">./hello</span><br><br>Although your shell script should work, it is recommended to force your shell script to run in a specific shell. This helps prevent your shell script encountering errors when run in the incorrect shell (i.e. syntax not recognized in a specific 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 script to be run in the Bash Shell. When your Bash Shell script finishes execution, you are returned to your current shell that you are using (which in our case in Matrix, is still the Bash shell).<br><br>
# Save your editing changes and exit your text editor.<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. 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 by issuingthe following:<br><span style="color:blue;font-weight:bold;font-family:courier;">./hello.bash</span><br><br>
::In the next investigation, you will learn to create and run shell scripts that<br>use variables, positional and special parameters.<br><br>
