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Tutorial10: Shell Scripting - Part 1

68 bytes added, 12:03, 3 March 2021

→‎INVESTIGATION 4: USING CONTROL FLOW STATEMENTS

# Copy and paste the following (correct) '''test''' command: [ $number1 -gt $number2 ] Issue a command to view the value of the exit status of the previously issued '''test''' command. You should notice that is works properly. '''Let's now learn about control-flow statements:''' '''Logic statements''' are used to create different paths or directions based on the result of testing conditions. In this tutorial, we will only focus on the '''if''' logic statement.

# Use a text editor like vi or nano to create the text file called '''if-1.bash''' (eg. vi if-1.bash) If you are using the nano text editor, refer to notes on text editing in a previous week in the course schedule.

# Enter the following lines in your shell script: #!/bin/bash clear num1=5 num2=10 if [ $num1 -gt $num2 ] then    echo "Greater Than" fi

# Save your editing session and exit the text editor (eg. with vi: press '''ESC''', then type ''':wx''' followed by '''ENTER''').

# Issue the following linux command to add execute permissions for your shell script: chmod u+x if-1.bash

# Run your shell script by issuing: ./if-1.bash Confirm that the output indicated a correct result.

# Use a text editor like vi or nano to create the text file called '''if-2.bash''' (eg. vi if-2.bash) If you are using the nano text editor, refer to notes on text editing in a previous week in the course schedule.

# Enter the following lines in your shell script: #!/bin/bash clear read -p "Enter the first number: " num1 read -p "Enter the second number: " num2 if [ $num1 -gt $num2 ] then    echo "The first number is greater than the second number." fi

# Save your editing session and exit the text editor (eg. with vi: press '''ESC''', then type ''':wx''' followed by '''ENTER''').

# Issue the following linux command to add execute permissions for your shell script: chmod u+x if-2.bash

# Run your shell script by issuing: ./if-3.bash What do you notice? Try running the script several times with numbers different and equal to each other to confirm that the shell script works correctly. Let's learn how to use a simple loop with shell scripting. In this tutorial, we will only focus on one simple use with the '''for''' loop.

# Use a text editor like vi or nano to create the text file called '''for-1.bash''' (eg. vi for-1.bash) If you are using the nano text editor, refer to notes on text editing in a previous week in the course schedule.

# Enter the following lines in your shell script: #!/bin/bash echo for x in 5 4 3 2 1 do    echo $x done echo "blast-off!" echo

# Save your editing session and exit the text editor (eg. with vi: press '''ESC''', then type ''':wx''' followed by '''ENTER''').

# Issue the following linux command to add execute permissions for your shell script: chmod u+x for-1.bash

# Run your shell script by issuing: ./for-1.bash

# Use a text editor like vi or nano to create the text file called '''for-2.bash''' (eg. vi for-2.bash) If you are using the nano text editor, refer to notes on text editing in a previous week in the course schedule.

# Enter the following lines in your shell script: #!/bin/bash echo for x do    echo $x done echo "blast-off!" echo

# Save your editing session and exit the text editor (eg. with vi: press '''ESC''', then type ''':wx''' followed by '''ENTER''').

# Issue the following linux command to add execute permissions for your shell script: chmod u+x for-2.bash

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