Assignment Specification

Write a shell script (to run on the Bourne shell) that allows a user to view,    add, or delete a setting in a configuration file (config.txt) that contains    settings in the form variable=value. The following is an example of such configuration file:

HOME=/u/soc/abc HOST=lawson HOSTTYPE=sun4 LOGNAME=abc OSTYPE=solaris PATH=/usr/dt/bin:/usr/openwin/bin:/bin:. PS1=$ PS2=> SHELL=/usr/bin/tcsh TZ=Australia/Tasmania USER=abc VENDOR=sun EDITOR=joe

Your script for this task must be named setting.sh. For ease of use, your     script must present a menu of operations that a user may choose from. After    the user makes a selection and that the selected operation has been                    completed, the menu must be displayed again so that the user can make           another selection. Validation check on user inputs is required (see the                following sample output about this). In the beginning of your script you need to check to see whether the required configuration file (config.txt) actually exists under the current directory (if not, your script displays a message and    then exits).

Here is a sample output of your script. The $ is the shell prompt. The items in italics are not part of the sample output. They are hints indicating how your   script should behave.

$ ./setting.sh *** MENU *** 1. Add a Setting 2. Delete a Setting 3. View a Setting 4. View All Settings Q – Quit CHOICE: 1 (user input) Enter setting (format: ABCD=abcd): (user simply presses the Enter/Return key) New setting not entered Enter setting (format: ABCD=abcd): EDITOR (user input) Invalid setting (A valid setting needs to contain a “=” sign) Enter setting (format: ABCD=abcd): EDITOR= (user input)

The variable name of the setting is: EDITOR

The variable value of the setting is:

Invalid setting .

(Hint: To retrieve a variable name before the “=” sign, research the expr command’s ability in handling strings)

Enter setting (format: ABCD=abcd): =vi (user input)

The variable name of the setting is:

The variable value of the setting is: vi

Invalid setting .

Enter setting (format: ABCD=abcd): 1EDITOR=vi (user input)

The variable name of the setting is: 1EDITOR

The variable value of the setting is: vi                            Invalid setting. The first character of a variable name cannot be a digit.

Enter setting (format: ABCD=abcd): EDITOR=vi (user input)

The variable name of the setting is: EDITOR

The variable value of the setting is: vi

New setting added .

*** MENU ***

1. Add a Setting

2. Delete a Setting

3. View a Setting

4. View All Settings

Q - Quit

CHOICE: 1 (user input)

Enter setting (format: ABCD=abcd): USER=jchen (user input)

The variable name of the setting is: USER

The variable value of the setting is: jchen                       Variable exists. Changing the values of existing variables is not allowed.                                                            *** MENU ***                                                       1. Add a Setting                                                   2. Delete a Setting                                                3. View a Setting                                                  4. View All Settings                                               Q - Quit

CHOICE: 2 (user input)

Enter variable name: EDTOR (user input) Variable does not exist. (Your script needs to check whether a variable exists or not) *** MENU ***                                                       1. Add a Setting                                                   2. Delete a Setting                                                3. View a Setting                                                  4. View All Settings                                               Q - Quit

CHOICE: 2 (user input)

Enter variable name: EDITOR (user input)

EDITOR=vi

Delete this setting (y/n)? y (user input)

Setting deleted (However, if user’s answer is n here, then the setting stays)

*** MENU ***

1. Add a Setting

2. Delete a Setting

3. View a Setting

4. View All Settings Q - Quit

CHOICE: 3

Enter variable name:USER1 (user input)

Variable does not exist. (Your script needs to check whether a variable exists or not)

*** MENU ***

1. Add a Setting

2. Delete a Setting

3. View a Setting

4. View All Settings Q - Quit

CHOICE: 3 (user input)

Enter variable name: USER (user input)

USER=abc

Requested setting displayed above.

*** MENU ***

1. Add a Setting

2. Delete a Setting

3. View a Setting

4. View All Settings Q - Quit

CHOICE: 4 (user input)

HOME=/u/soc/abc

HOST=lawson

HOSTTYPE=sun4

LOGNAME=abc

OSTYPE=solaris

PATH=/usr/dt/bin:/usr/openwin/bin:/bin:.

PS1=$

PS2=>

SHELL=/usr/bin/tcsh

TZ=Australia/Tasmania

USER=abc

VENDOR=sun

*** MENU ***

1. Add a Setting

2. Delete a Setting

3. View a Setting

4. View All Settings Q - Quit

CHOICE: 5 (user input)

Invalid choice.

*** MENU ***

1. Add a Setting

2. Delete a Setting

3. View a Setting

For Your Assignment Script

You must

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Include your name, student ID, and a brief introduction of what the script does as a comment in the beginning of the script.

Make your script run on the Bourne shell, regardless of which shell the user of your scripts is currently on.

Add in-line comments to help other people understand your script. Use “\n” where appropriate to make the output of your script more readable.

Note that your script structure and layout are also important as they will be marked as part of the assessment process.

Submitting Your Assignment

You must submit a single folder named kit213agn which contains the          following two (2) files, electronically to the kit213submit folder which will be created for you in your ictteach home account:

setting.sh, config.txt

(Please make sure that your kit213agn folder only contains the two files as listed here, when you are ready to submit them.)

To submit your assignment, follow these three steps:

1). Ensure that both your kit213agn folder and your kit213submit folder are stored right under your home directory;

2). Run the following commands to copy your kit213agn folder into your kit213submit folder (the $ is the shell prompt):

$ cd (This takes you back to your home directory from anywhere) $ cp -r kit213agn kit213submit (This copies your assignment folder into your kit213submit folder. The option -r is important) $ ls -l kit213submit (This verifies that your assignment folder is now in your kit213submit folder) $ ls -l kit213submit/kit213agn (This verifies that your assignment files are now in your kit213submit folder)

3). Immediately use your mobile phone (or a snipping tool installed on your   laptop) to make a screenshot of your secure shell window (such as PuTTY       window) and submit the image file to KIT213 MyLO (under Assessments, then Assignments), as proof of your assignment submission. Use your name and ID number as the image file name, for example, Smith_John_012345.jpg. If   your assignment files are copied into the kit213submit folder by the            deadline, you do not receive any penalty if this image file is slightly late.