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→INVESTIGATION 1: CREATING A SHELL SCRIPT
# 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$USER"</span><br><br>'''NOTE:''' The variable called '''USER''' is an '''environment''' variable that contains the current user's login name. In this way if you wanted to share your shell script with other users, when they run the shell script it will greet by <u>their</u> username. Using ''environment variables'' makes your shell script to be more "usable" by others.<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 add execute permissions prior to running the shell script.<br><br>
