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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'''<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;font-weight:bold;">echo<br>echo "Hello $USER"<br>echo</span><br><br>'''NOTE:''' The variable called '''USER''' is an '''environment''' variable that contains the current user's login name.<Br>In this way if you wanted to share your shell script with other users, when they run the shell script<br>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.<br><br>Instead of issuing the '''bash''' command followed by your shell script pathname as an ''argument'',<br>let's simply run it by its filename. This is the most common method of running shell scripts.<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>
